A triangular symbol made of three "chasing arrows" containing a number in the middle and special letters on the outside is used to identify the different types of plastic. The following are the letters of identification and their meaning:

1. PETE - Polyethylene Terephthalate - PETE is most often used for cooking oil bottles, soft drink bottles, and peanut butter jars.

2. HDPE - High Density Polyethylene - HDPE is commonly used for milk jugs and detergent bottles.

3. PVC - Polyvinyl Chloride - PVC is used for plastic pipes, water bottles, outdoor furniture, shrink-wrap, liquid detergent containers, and salad dressing containers.

4. LDPE - Low Density Polyethylene - LDPE is often used for trash can liners, dry-cleaning bags, produce bags, and food storage containers.

5. PP - Polypropylene - PP is used for drinking straws and bottle caps.6. PS - Polystyrene - PS is used to make packaging pellets, commonly referred to as

"Styrofoam peanuts."7. OTHER - Plastics listed in the OTHER category are any not listed in the first six

categories. Certain types of Tupperware and other food storage containers commonly fit within the OTHER category.

The many different types of plastic has made recycling plastic difficult, particularly because the process of sorting plastics cannot be automated. In fact, recycling plastic is labor intensive since reading the special triangular symbol can only truly identify most plastic items.

Biodegradable Plastic

Currently, there is research taking place in the area of biodegradable plastic. The goal is to develop a type of plastic that can naturally break down from exposure to sunlight. By mixing starch with the plastic, it can be made to degrade more easily. It does not, however, cause the plastic to break down completely.

A genetically engineered bacterium capable of synthesizing biodegradable plastic has also been developed. This material, however, is quite expensive to create at this point. Currently, BASF does make a biodegradable polyester called Ecoflex that is used for food packaging applications. Unfortunately, carbon gets locked up in these biodegradable plastics and is released into the atmosphere as carbon dioxide.

Another downside to these biodegradable plastics is that they require sunlight to degrade. Therefore, this type of plastic really only helps with roadside litter. Plastics buried in landfills will not receive the sun they need to degrade and, therefore, can still last for decades.

While there are still many questions left unanswered when it comes to the environment and plastic, it is clear plastic is here to stay for a very long time.

9 June 2010MUSCAT -- On the occasion of World Environment Day, celebrated recently, Oman Plastic Industries began the manufacture of Oxo-Biodegradable plastic bags for the first time in Oman.

Oman Plastic Industries is officially certified by the Directorate-General of Specifications and Measurements of Oman to manufacture the oxo-biodegradable plastic carry bags, after completing the necessary test run with the co-ordination of the local distributors of the d2w additive in Oman.

Oxo-biodegradable plastics, with a pre-programmed life, significantly reduce the harmful effect on the environment. At the end of its useful service life, they degrade in the environment by a combination of oxidation and biodegradation. During its service-life, strength and other qualities are the same as ordinary plastics.

The plastic eventually breaks down to water, carbon dioxide, biomass and trace elements, on land or sea, in the light or dark, in heat or cold.

It leaves no fragments or methane or harmful residues thus avoiding pollution and damage to the environment and wildlife.

Oxo-Biodegradable plastics do not need a highly-microbial environment to degrade. It will happen even if the plastic is left in the open or in the sea.

Ecomagination from GE - with innovation, there will be more clean water for everyone The plastic is made oxo-biodegradable with the addition of d2w additive when the plastic product is being manufactured. d2w products have been available for more than four years and are now used in more than 50 countries by major retailers, hotel groups, food manufacturers, etc.

The additive does not have any toxic effect and is totally soil safe as per the ATM D 6954 -- 04 Standard which tests plastics that degrade in the environment by a combination of oxidation and biodegradation.

The world produces and uses 20 times more plastic today than it did 50 years ago. Ordinary plastics can take up to 400 years to break down. Given plastic is a fundamental part of our day-to-day lives, it is time to move on to a more earth-friendly product like degradable plastic.

"With the technology now available in Oman, it empowers retailers and organisations who think 'Green' to show their care for the environment," says Tariq Ali Mirza, Managing Director of Oman Plastic Industries.

By Staff Reporter

HDPE Plastics

Ubiquitous in every day life and accounting for the bulk of material used to create milk bottles, laundry detergent bottles, and margarine tubs, it may surprise some readers to learn that HDPE plastic actually begins life as thick black crude oil pumped out of the ground.

HDPE plastics are produced from a component of crude oil, naphtha, which is cracked (heated at very high temperatures) in order to extract the ethylene gas which is released when the chemical structure of naphtha deteriorates. The ethylene gas is then polymerized, a process which involves the free gas particles joining together to produce long chains of ethylene molecules.

There are many different types of polyethylene. HDPE is a particular type of polyethylene with a very dense linear structure which gives it an increased tensile and molecular strength. HDPE is normally defined as being polyethylene with minimum density of 0.941 grams per cubed centimeter. Within the category of HDPE plastics, molecular weights range from 100,000 to 500,000, which is where the great variance in HDPE grades arises. Common grades of HDPE plastics include blow molding grade HDPE plastics, injection molding grade HDPE plastics, film grade HDPE plastics, and pipe grade HDPE plastics. Each of these grades have slightly different physical properties, the most notably important one being MFI, or melt flow index. Melt flow index describes how quickly the HDPE plastic flows when in liquid form, applications such as pipe making and blow molding require a highly viscous slow flowing HDPE plastic, whereas injection molding requires a quickly flowing HDPE resin.

HDPE plastics were first invented in the 1950’s, though it took some time to discover ways to reliably produce large amounts of homogeneous HDPE, as the processes under which HDPE is produced must be tightly controlled in order to produce the different grades of HDPE.

Ethylene naturally polymerizes at high temperatures and pressures, but it is not commercially viable to operate facilities under these conditions. So instead, catalysts are used to lower the temperature at which polymerization will take place, and also direct the type of polymer which results. HDPE’s largely linear structure with little molecular branching is commonly produced by Zeigler-Natta catalysts, or chromium catalysts.

HDPE lends itself well to recycling, and a great deal of reprocessed HDPE, recycled HDPE, and regrind HDPE is available on the market. The bulk of recycled HDPE plastics are post consumer scrap reclaimed from kerbside recycling programs. Millions of tons of HDPE plastic milk bottles and other household vessels are collected and recycled every year. For the most part, recycled HDPE plastics are equally as useful as virgin HDPE plastics, though they may not be used in food contact applications. There is some risk that contaminants found in the scrap HDPE from which recycled HDPE is made may pass through the various cleaning and filtration steps and degrade and contaminate the end product. If one is dealing with a reputable supplier, and the specific application is not

overly intensive, recycled HDPE is an economically sound alternative to virgin HDPE plastic.

Plastics can be biodegradable because they are already made by chemical reaction. Plastics are derivatives of hydrocarbon. And only those things can be biodegrade those are related to living organisms like paper, fruits waste ,skin or even cloth

INTRODUCTION: During the past 25 years, plastic materials have gained widespread use in the food, clothing, shelter, transportation, construction, medical and leisure industries. Plastics offer a number of advantages over alternative materials – they are lightweight, extremely durable, and relatively unbreakable. However, plastic materials also have several disadvantages, one of the largest being that plastic does not break down in the environment. Materials such as wood and paper are subject to breakdown from microorganisms (biodegradation). Plastics are composed of petroleum-based materials called resins (e.g., polyethylene, polypropylene) – materials that are resistant to biodegradation and because of this resistance, plastics that are disposed of in landfills will remain in their original form in perpetuity. Every year, large volumes of plastics are disposed of in U. S. landfills – in 1995 alone, an estimated 20 million tons of plastic products were disposed of in landfills.

TYPES OF BIODEGRADABLE PLASTIC

1) Starch based plastics:  These are 'compostable' plastics made from various food substances and they compostable because they will completely  biodegrade within 4 months in a commercial composting plant.  Please be aware that they do not decompose in a home composting facility because elevated heat is required to compost them.  PLA is the best known type.  The largest manufacturer of starch based plastic is reported as saying that they will create methane if placed into the anaerobic zone of landfills. This kind of plastic is best suited for composting in commercial composting facilities where food and garden waste are composted but undesirable in landfills.

2) Oxo-biodegradable conventional plastics:  These are conventional plastics with an additive added to them that cause them to biodegrade.  They require a two part process to biodegrade, all parts of which must occur in the open air or in soil that is aerated . The first half of the process requires either heat, UV light or mechanical stress. The second part of the process occurs when bacteria consume the partly decomposed plastic. This type of plastic is best suited where littering is the primary concern. Important to note that this type of plastic cannot be composted and there is no ecological advantage when placed in landfills.

3) Microbiodegradable conventional plastics:  These are conventional plastics to which a special additive has been added causing them to

biodegrade naturally.  This additive works only in soil that has naturally occurring micro organisms. It will biodegrade without the need for oxygen, UV light, heat or mechanical stress.  In an oxygenated environment it decomposes into humus, carbon dioxide, and water.  In an oxygen deprived atmosphere it decomposes into humus, methane and water. This kind of plastic is not recommended for composting because it takes somewhat longer to biodegrade than the typical commercial composting cycle, but it is excellent for disposal in landfills.

In order to produce plastics that degrade in a landfill setting another scientific approach was necessary. Company Y has developed an alternative method for creating microbiodegradable plastics. This method involves a proprietary combination of organic and inorganic chemical materials which have been mixed in a very precise formulation and compounded into a reactor-grade master batch pellet. When this pellet is compounded with any polyethylene or polypropylene resin, the resulting plastic is biodegradable. The biodegradation of X-treated plastic occurs through aerobic (oxygen dependant) and anaerobic (dependent on the absence of oxygen) pathways. Micro organisms consume the plastic, assimilating the material for cellular processes and producing a mixture of metabolic products (principally methane, carbon dioxide, and water).

PLASTICS SYNTHESIZEDThe C process may be utilized in the manufacture of bags, agricultural film, landscape netting, diaper liners, and numerous other products. The viability of C-treated plastic as an environmentally safe, biodegradable product was evaluated by conducting standard tests on X pellets and plastic film which were created using the X process. Biodegradation tests were conducted to determine the susceptibility of the products to biodegradation. In addition, chemical analyses and standard plant and animal toxicity tests were conducted on the end product of the biodegradation process to determine the safety of the product. The results of these tests are discussed below.

2.0 BIODEGRADATION TESTS

Laboratory testing is a common method used to determine the susceptibility of compounds to biodegradation. Testing methods have been developed and standardized by several organizations including the American Society of Testing Materials (ASTM), Organization for Economic Cooperation and Development (OECD), and European Standards Organization (CEN). The method employed by the various tests involves adding a small amount of test compound (in this case, X pellets or plastic film) to a large amount of a material called inoculum (a highly active substance used to grow microorganisms).

The test is run at the same time using a reference compound that is known to be biodegradable, also added to inoculum. Biodegradation can be evaluated by measuring the amount of methane and carbon dioxide produced. Using this result, the percentage of sample that has biodegraded is calculated as the percentage of solid carbon of the sample that has been converted to gaseous, mineral carbon. If the results from the test and reference materials are similar, the test material has biodegradable properties.

“Biodegradable Plastic”, what does it mean and why is there so much confusion about something that sounds easy to explain? The ASTM defines biodegradable plastics as “a degradable plastic in which the degradation results from the action of naturally occurring micro-organisms such as bacteria, fungi, and algae”. Sounds simple enough, so why all the confusion? The confusion really arises from two aspects. Confusion between the use of the term degradable vs biodegradable and the very loose use of the word biodegradable.

In the market place today there are three categories of plastics that biodegrade or degrade. Those technologies are PLA (Polylatic Acid), Oxo-degradable and a new technology called Microbiodegradable. Now that we know this, how do we know which ones biodegrade or degrade?

P

PLA PLASTIC:

PLA is a bioplastic made from starch; specifically it is being manufactured from starches derived from genetically modified corn (GMO food). This technology and supporting organizations such as BPI (Biodegradable Products Institute) claim that PLA biodegrades. However, this claim is confusing because they are using the term “biodegradable” extremely loosely.  PLA is a “compostable plastic” in that it goes through “degradation” to break down and is therefore not true “biodegradation”. PLA does not break down or biodegrade in a landfill and will only begin to “degrade” after being exposed to heat (specifically 60° C over a five day period).  This kind of environment can only be found in a commercial composting facility, NOT in the domestic composter in your garden. We find that many of the articles and organizations who support PLA are greatly contributing to the confusion by not using correct standards based definitions of that technology. Once PLA composts the remnant is CO2 and because professional composting facilities are not currently capturing the gas it is usually released into the atmosphere.

OXO-BIODEGRADABLE PLASTIC:

Next we have oxo-biodegradable, as the name implies this technology allows the product to degrade. This particular technology incorporates the use of an additive that begins to break the plastic chains only when exposed to oxygen, heat and moisture.  Although this technology is fairly upfront with the type of degradation taking place, the marketing materials suggest that once the pieces of plastic have broken down into small enough fragments there is a second stage that gives microbes the opportunity to finish the process through biodegradation.  This aspect may be true but it is extremely difficult to validate as the plastic fragments must have degraded to the microbe level.  There are varying reports as to what remains in the soil and air once an oxo-degradable product has degraded.  These range from heavy or low metals, salts, CO2 and. Because

many of these products will degrade in a landfill the  CO2 gas will normally be captured and released into the atmosphere.

MICROBIODEGRADABLE PLASTIC:

Moving on to the final technology we have third generation microbiodegradation. This is the technology behind Biogreen Products. This technology is also in the form of an additive which is added to existing polymers. Biogreen Products use organic compounds to open the polymer chain and attractants stimulate microbial colonization on the plastic.  Because the polymer chain is open the micro organisms can use the carbon chain as a source of food and energy. This is happening at the atomic level and the remnants are CO2, CH4 and inert humus and because many of these products will degrade in a landfill the gases of CO2 and CH4 will be captured, released or burned. It is also important to note that this process activates with or without the presence of air, light or heat and will take place no matter how deep the plastic is buried. This type of plastic can also be recycled in the normal way.

CONCLUSIONS:

So there we have it in a nutshell. We now know the difference between the three, degradable, oxo-biodegradable and microbiodegradable.  It still leaves the bigger question as to which technology and method is better for the environment? This is another important question and requires further explanation, however you should always keep in mind the overall net impact to the environment.  When trying to answer this environmental question it is important to keep in mind the following criteria: using food to create plastics, pesticides that effect water, total water consumption, total fossil fuels used in processing, greenhouse gases emitted in processing and breaking down, the benefit of the product, does the biodegradation or degradation create any benefits such as clean energy? Is it sensible to use vast amounts of food to create plastic that could otherwise be used to feed the worlds’ hungry. Will the degradation take place deep in the landfill and are the products acceptable for commercial recycling.

many thanks for taking the time to read this article and I hope that you found it informative.

Kind Regards

Why Plastic Degrades Not Biodegrades.

August 1, 2008

Biodegrading, the breaking down of organic substances by natural means, happens all the time in nature. We live, we die, we rot and so we feed the next generation – that’s life. Even if you are a rock. All plant-based, animal-based, or natural mineral-based substances will over time biodegrade.

In its natural state raw crude oil will biodegrade but man-made petrochemical compounds made from oil, such as plastic, will not. Why not – because plastic is a combination of elements extracted form rude oil then re mixed up by men in white coats. Because these combinations are man made they are unknown to nature. Consequently there is no natural system to break them down. The enzymes and the micro organisms responsible for breaking down organic materials that occur naturally such as plants, dead animals, rocks and minerals, don’t recognise them.

This means that plastic products are pretty much indestructible in a biodegradable sense at least. Which is in many ways fantastic and plastic is indeed a wonder product. But there is a downside. What happens to plastic in the environment?

DEGRADINGAs time passes plastic will eventually break down into smaller and smaller pieces. This is a mechanical process involving mechanical actions such as ripping splitting and falling apart. Plastic merely breaks up. No matter how small the pieces they are still and always will be plastic. they are not absorbed into or changed by natural processes.

Dr Richard Thompson of the University of Plymouth has identified plastic particles thinner than the diameter of a human hair. But while they cant be seen those pieces are still there and are still plastic. They are not be absorbed into the natural system they just float around within it. He estimates that there are 100,000 particles of plastic per sq km of sea bed and 300,000 items of plastic per sq km of sea surface. Barnacle, lugworm and amphipods hoover up the tiny plastic particles as they feed. Who eats the amphipods – the little fishes and who eats the little fishes? That’s you that is with your fish, chips and microscopic plastic particles.

Have you ever wondered why the plastic bags from ShoeMart have the word “BIODEGRADABLE” on it? I also noticed this with the plastic bags used by National Bookstore, Max’s Restaurant and some shops in Hong Kong and Singapore. I was curious about it, because from what I know, plastics are not biodegradable (others say it is but will take thousands of years in the process).

 

A bag from SM Hypermart. Biodegradable? 

A bag from Max's Restaurant. Made by EPI. 

A plastic bag from Hong Kong. I got this from a fruit stand. Made by EPI as well.

I looked it up on the net and found out some things. The EPI company who manufacture plastics for Max’s uses Totally Degradable Plastics Additives (TDPA™), which enables plastics to degrade and in most cases biodegrade when discarded, into environmentally benign products within a few months to a few years as compared to decades or longer for the same products made without the benefit of the technology.

So yes it is biodegradable, but will still take time. It will still end our at dumpsites. I am still unconvinced about this because Filipinos have a voracious consumption of plastic bags. This may have been a good start in the part of retailers like SM, Max’s and National Bookstore but it is still up to the people to use them responsibly. We have to do our part in recycling, reusing and reducing plastics.

With garbage dumps overflowing and our oceans getting filled up with plastic products, we need to do our part to save our future. For plastic bags alone, it is estimated that some 430,000 gallons of oil are needed to produce 100 million pieces of these omnipresent packaging items on the planet. We need to reduce the demand for plastics to decrease the amount of carbon dioxide that will be the byproduct of the manufacturing process. Even if we make use of the "biodegradable" plastics, it is still not the best option.

I personally believe that we should NOT use plastics anymore but utilize "green bags". Locally, we have our "bayong", but you need not be old school to help. When I buy some things, I usually ask the cashier not to pack my items. I just put it in my backpack, in that way I am able to help decrease the demand and I know that i will be decreasing my less carbon footprint in the future.

Consumers can also lobby local and national authorities to pass ordinances and laws that will ban plastic bags like what China and San Francisco did, or impose tax on plastic bags like that in Ireland that resulted to a 90 percent drop in plastic bag use during the past five

years.

At the Senate, Sen. Miriam Defensor-Santiago filed Senate Bill No. 1443 or the Plastic Bag Recycling Act, while Sen. Manny Villar filed Senate Bill No. 1802 requiring malls and stores to use environmentally-friendly shopping bags in place of plastic bags.

But we must not wait for these bills and laws to be passed, and we must act by reliving our "bayong" days and saying NO to plastic now if we would want a better world to live in.

biodegradable plastics

June 2, 2009 at 10:59 pm (cool green technology, environmental awareness, plastics, stopping pollution) Tags: biodegradable plastic, pollution prevention, stopping pollution

a colleague of mine, ms. carol lee wrote me tis note:

Hello Eric,

Just late last year, I noticed that the yellow shopping bags of SM (Shoe Mart) have ‘biodegradable’ printed on them.  Until then, I have always thought their bags are made of plastic.  How can one tell whether a bag is actually manufactured using biodegradable plastic or not?

Thank you and looking forward to hearing from you on the above.

All the best,

Carole

der was a time wen plastic bags (lotz wer from sm supermarkets) on unsanitary landfills, sewer canals, rivers & even in manila bay r regularly seen on photos in newspapers & magazines….

plastic bag pollution

shoemart noiselessly introduced deir oxo-biodegradable plastic (obps) bags as well as d re-usable green bags (can last up2 2yrs or 100 grocery trips, accordingly) 2address d problem.

d question is….do we really need a plastic bag dat will last a hundred years? biodegradable plastic bags (sm obps bags decompose after 6 months) r cool coz of low enviro impact…

obps

sm green bag

biodegradable plastic bags can b identified fr deir labels. see pix bellow. f plastic bags r not labeled so, den dey’r not!

giordano (a clothes shop) have bio-bags 4deir customers….

giordano bio-bag

in d past (wen brandenberger invented it in 1908), cellophane wer made fr plants b4 petrochemical based plastics became d cheapest alternative.

pple say dat biodegradable plastics r more expensive dan regular plastics…according 2a friend (who’s familiar w/ d supplier of sm), sm didn’t spent too much more in deir biodegradable bags due 2d volume scale (only 12% more expensive according an sm insider)…..guess, cost s always a reason 4pple 2justify dat we can pollute d earth….

using re-usable bags (cloth bags, ‘bayong’, etc.) s d best way 2go……in europe, one has 2pay 4plastic bags if u don’t hav ur own re-usable bags…tis actually lessens d amt of plastic bag waste….

we need 2stop pollution fr plastics……

a friend from d phil. pollution prevention roundtable (p3r) 4warded a plastic bottles ppt. 2view it, click on d link bellow:

bottled water

Bigla akong binatukan ng boredom. Kaya ay naisipan kong magbasa ng newspaper (Philippine Daily Inquirer). Himala nang bumasa ako sa business section, dahil kapag bumuklat ako ng newspaper, laging nalilipad ang ilong ko sa entertainment category.

So, talagang nagbasa ako ng dyaryo. Something about SM with it’s new biodegradable plastic bags. Sa totoo lang, and infairview, natuwa ako sa idea na ito ng SM. Isipin niyo, how many years or centuries pa bago tuluyang ma-disintegrate ang mga plastic. Which is also why, pilit nireremind satin na as much as possible eh i-recycle natin ang mga plastic bags sa kadahilanang mahirap i-dispose ang mga plastic. Kaya naman eh yung Biodegradable plastic bags ng SM eh talagang advantage para sa environment, lalo na sa environmental issue about trash.

“It looks like plastic but it is not plastic. It has zero lead content and zero metal content,” Mayor Reinaldo Bautista Jr. said.

“It’s very safe and it’s biodegradable, and will fully disintegrate in six months or less. It turns into powder and blends with the soil after a few months.”

Oh diba? Bonggang-bongga ang matutulong nito sa environment natin. Lalo na ngayon na super duper laganap na ang global warming. Nakaka-alarma talaga. Kasi naman, malapit na ang summer, pero madalas, malamig dito sa Davao. And yes, isa yan sa mga resulta ng global warming. Kaya kayo, isip na kayo ng mga ways kung paano makakatulong sa environment. Nakaka-takot kaya. Baka matulad tayo sa “Day After Tomorrow”. When nature is the one who causes the difficulty, it will unfortunately be considered as a plague.

Na-curious ka ba sa Biodegradable bags ng SM? Read more here.

SM Supermalls use more expensive plastic bags05/08/2008 | 02:44 AM

DAVAO CITY, Philippines - Although most businessmen would rather opt for cheaper and lower overhead costs to post a bigger profit, the SM Supermalls beg to differ.

"The bags that we are using right now is 12 percent more expensive than the ordinary plastic bags," Melbert Villanueva, assistant store manager of SM Supermarket, said in an interview last Tuesday.

The SM Supermarket and the SM Department Store have already shifted to the use of biodegradable plastic bags.

"We use about 300,000 large-sized plastic sando bags for our grocery and about 200,00 large-sized plastic sando bags for the department store," Villanueva said.

"This is at no extra cost to our customers," Villanueva added.

Villanueva also said the biodegradable bags now being used by the supermarket and department stores of SM City Davao only have a life span of six months in contrast to the 100 year lifespan of ordinary plastic bags.

"The moment it is exposed to sunlight, its deterioration starts," Villanueva said.

Villanueva added that aside from the plastic bags, SM Supermarket is also encouraging the use of the green bag, a canvass bag that can be reused instead of the plastic bags.

"There are about 1.5 million green bags that have already been released," Villanueva said.

Plastic recycling symbols

Plastic can take up to 500 years to degrade if not recycled  

There are many different types plastic and it is a difficult and expensive material to recycle.   We currently offer collections of some plastic items via your recycling collection box, at the Household Waste Recycling Centres and at the bring banks. 

The following symbols are displayed on packaging and will assist you in identifying what the material is and if it is suitable for recycling:

 Symbol Polymer type Examples Recyclable?

PET

Polyethylene Terepthalate

These tend to be transparent bottles that can be easily squashed:

Fizzy drinks bottles Mineral water bottles Bottles for squash Cooking oil containers Oven-ready meal trays 

Green recycling box Household Waste

Recycling Centre Local recycling

points

HDPE

High DensityPolyethylene

These tend to be opaque and coloured bottles:

Milk bottles Juice bottles Washing up liquid Bath and shower bottles

Green recycling box Household Waste

Recycling Centre Local recycling

points

PVC

Polyvinyl Chloride

These tend to be transparent bottles that are more difficult to squash. 

Food trays Cling film Bottles for squash Mineral water Bath and shower bottles

Green box Household Waste

Recycling Centre Local recycling

points

LDPE

Low DensityPolyethylene

Many types of packaging are made from this material:

Carrier bags Bin liners

Supermarkets

PP

Polypropylene

Many types of packaging are made from this material:

Margarine tubs microwaveable meal

trays

Due to the mixture of compounds these plastic types are hard to recycle and are not recycled by Wakefield Council.

PS

Polystyrene

Many types of packaging are made from this material:

Yoghurt pots fast food containers foam meat or fish trays vending cups protective packaging

for white goods and toys

Due to the mixture of compounds these plastic types are hard to recycle and are not recycled by Wakefield Council.

OTHER

All other resins and multi- materials

Any other plastics that do not fall into any of the above categories.

An example is melamine, which is often used in plastic plates and cups.

Due to the mixture of compounds these plastic types are hard to recycle and are not recycled by Wakefield Council.

 Biodegradable plastics

Biodegradable plastic bags and packaging aren't an end solution to replacing non-degradable plastic bags in supermarkets and retails stores for the following reasons:

They do not decompose in properly managed landfills. They support the throwaway mindset and the use of landfills as an acceptable

disposal method They do not discourage over-use in the first place.

Definitions of bioplastics:

Compostable plastic: A plastic that undergoes biological degradation during the composting process (up to 2-3 months in a windrow) to yield carbon dioxide, water, inorganic compounds and biomass at a rate consistent with other known compostable materials and leaves no visually distinguishable or toxic residues.

 Biodegradable plastic: A degradable plastic in which the degradation must result from the action of naturally occurring microorganisms over a period of time (up to 2-3 years in a landfill).

Degradable plastic: An oil based plastic containing a chemical additive that undergoes significant change in its chemical structure causing it to break down into smaller particles. The degradation process is triggered only when material is exposed to specific environmental conditions (such as UV, heat and moisture). Residues are not food matter for microorganisms and are not biodegradable or compostable.

Examples of bioplastics:

Scion (Rotorua, NZ) has developed a range of commercial biodegradable plastic formulations compounded in NZ, using commercial bioplastics such as poly lactic acid (PLA) and others, which intelligently or programmably biodegrade in soil or other environments. Such products (eg plastic moulding compounds or masterbatches for extrusion or injection moulding etc) are now available on a commercial basis through a NZ manufacturer. Scion develops new materials and formulations for biodegradable plastics and other functional bioplastics by using renewable biobased resources and their process residues as sources of chemical or polymer additives. Such additives are also useful in other polymer products such as adhesives, coatings, foams, or composites and fibre based materials.  Scion has extensive experience in testing and formulation of biodegradable plastics and bioplastics. For more information click here or contact Alan Fernyhough at the Scion. alan.fernyhough@scionresearch.com

New Zealand Potato Plate Company, based in Blenheim, makes "100% biodegradable and compostable" disposable packaging, such as plates, from potato starch. Its products are sold through supermarket chains Progressive and Foodstuffs in the South Island. The company is promoting the products as being suitable for all fast food, microwave, and freezer use and says that they have excellent insulation qualities and fully degrade in days after use.  All products are made from food-grade raw materials with no preservatives or toxins of any form. The used product is put straight on the compost heap and worm bin or fed to pigs.  For more information on biodegradable and compostable food packaging go to www.potatopak.com and www.earthshell.com 

Novamont, Italy manufactures Mater-Bi. Their promotional material says that it is a new generation of bioplastics derived mainly from natural renewable resources, including starch. Minimizing environmental impact it maintains the same characteristics of plastics but is "completely biodegradable within a composting cycle". www.novamont.com

The Cooperative Research Centre for International Food Manufacture and Packaging Science (Melbourne) says it has developed "the most advanced biodegradable packaging in the world", made from cornstarch. It eventually disintegrates when exposed to water and in the long term disappears completely. This product would be suited to some aspects of putrescible collections, food packaging and farming. (Ref: www.theage.com.au)

Plantic Technologies, Australia, has developed Bioplastic packaging – "biodegradable" food packaging that it says is cheap enough to compete with conventional plastic. The cornstarch–based material has the look, feel and flexibility of conventional plastic and can be used for a range of items, from cellophane to plant pots and medical devices. It biodegrades at 33 degrees Fahrenheit, after exposure to both moisture and microorganisms in the soil. (Ref. Wired, 26/06/02)

Other contacts and resources

'Green Plastics: An Introduction to the new science of Biodegradable Plastics, 'E.S. Stevens

The Institute for Local Self Reliance created the 'Carbohydrate Economy Clearinghouse' to provide accessible, up-to-date information spanning all facets of the 'carbohydrate economy'. (Carbohydrates, the building blocks of plant matter, can be converted into chemicals, energy, textiles, building materials, paper, and many other industrial products. They call this new materials base a 'carbohydrate economy'.)    Go to www.carbohydrateeconomy.org for more details. Go to the search function and type in packaging and here you will find comprehensive information on plant matter-based products, cutting edge companies (and cooperatives) producing them and reports on developments in this rapidly expanding field.

The International Biodegradable Products Institute (BPI) is a multi-stakeholder association of key individuals and groups from government, industry and academia which promotes the use and recovery of biodegradable polymeric materials. BPI aims to accomplish this goal through education, adoption of scientifically based standards and cooperative activities with other organizations in the USA, Canada, Europe and Japan. Ever since the introduction of 'biodegradable plastics' fifteen years ago, confusion and scepticism about claims and product performance has prevailed. This situation stems largely from plastic products that did not biodegrade as expected, yet were able to make claims because no scientifically based test methods and standards existed. However, along with the advancement of technology, standards have been developed.   The 'Compostable Logo' has been designed for consumers, composters, regulators and others to reduce confusion about bioplastics. It is a recognisable brand (that can be placed on the actual product, packaging materials and sales literature) and builds credibility and recognition for products that meet the American Society for Testing and Materials Standards.Go to www.bpiworld.org for more details.

Plastic Dangers

Common Plastics in the Home

Plastic Dangers - A deeper look at some of the common plastics found in the home interior: PET, PETE, HDPE, LDPE, EPS, PC, PU, ABS, Melamine.

Polyethylene-Terephthalate (PET, PETE)

Category 1, clear, tough, durable, shatterproof, able to contain carbon dioxide, carbonates soft drinks, obstructs oxygen, water and carbon dioxide. American Chemistry Council, PET has been approved as safe by the FDA and the International Life Sciences Institute (ILSI) when for single use. Building block: Ethylene glycol and dimethyl terephthalateAdditives: UV stabilizers and flame retardants

Plastic Dangers Health: Liver problems, reproductive problems, linked to cancer. Leaching: Reuse causes leaching into food and water, water left in containers for long periods release higher concentration levels of antimony. Offgasses VOCs Products: Packaging, drink bottles, salad dressing bottles, mouthwash bottles, food jars, microwave dishes soft drink, juice, water, beer, mouthwash, peanut butter, salad dressing, detergent and cleaner containers. Recyclable: High recycling rateRecycled products: Bags, food and non-food containers, fabric, trainers, luggage, upholstery, furniture, carpet, sleeping bag stuffing, coat filling, industrial strapping, sheet, and film, car parts (luggage racks, bumper, grill, door panels), fuse boxes

High-density Polyethylene (HDPE) Category 2, tough, strong, moisture resistance, chemical resistance, suitable for packaging products that have a short life span. Easy to form and process, gas permeable. Building block: Carbon and hydrogenPlastic Dangers Health/Leaching: Documented as safe according to guidelines. Offgasses VOCs Products: Opaque milk cartons, water bottles, juice cartons, household product bottles, personal care bottles, bin bags, pipes, tiles, cling film, plastic sheets, buckets, recycling bins, plastic crates. Recyclable: YesRecycled products: Drainage pipe, liquid laundry detergent bottles, oil bottles, pens, benches, doghouses, recycling containers, floor tile, picnic tables, fencing, lumber, and mailbox posts.

Low-density Polyethylene (LDPE) Category 4, tough, flexible material, opaque/translucent, strong, good chemical resistance, breakable. Building block: Carbon and hydrogenAdditives: Solvents Plastic Dangers Health/Leaching: Documented as safe according to guidelines. Offgasses VOCs Products: Flexible bottles, bin bags, cling film, lining of milk cartons, packaging, toys, plastic food bags. Recyclable: Yes Recycled products: Bin liners, furniture, panels, bins, lumber, sheets & film, composters, PC parts, playground slides, worktops.

Polystyrene (PS) Expandable Polystyrene (EPS)

Category 6, known as Styrofoam, can be manufactured as a foam or rigid. Good insulator at low temperatures, low density, low weight, highly flammable, foam ignites easily. Polystyrene in cavity wall insulation and building materials must conform to fire

regulations. Building block: Benzene, styrene, 1,3-butadienePlastic Dangers Health: Benzene is a known carcinogen. Combined butadiene and styrene (in ABS) take on the characteristics of benzene. Reproductive & development problems, neural and nervous system problems, hormone disrupter, Polystyrene is linked to cancer. Environment: Production vapours erode ozone. Foam does not easily decompose, it is a major contributor to marine debris and recorded to cause starvation to marine wildlife and birds. A report detailed that EPS is second place in materials that have the highest environmental impact. Many US states have banned Polystyrene. Present in second hand cigarette smoke and car exhaust fumes. Leaching: Leaches styrene into the air. Leaches into food containers where hot oil is present in food. Products: Foam insulation, building materials, furniture foam packaging, electronics, packaging, disposable cups, take away containers, disposable cutlery, CD case, cups, plates, bowls, trays, bottles, egg boxes Recyclable: Difficult to recycle, low scrap value, easier to recycle than PVCRecycled products: Light switches, insulation, vents, packing, takeaway containers, rulers, egg boxes.

Polycarbonate (PC) Category 7, polycarbonate plastics and epoxy resins, 6 billion pounds of BPA are produced and used annually. Lightweight, hard, clear, durable, break resistance, single use or refillableBuilding block: Bisphenol A (BPA) Additives: Highly toxic phosgene, derived from chlorine gas. Requires solvents for production; methylene chloride, a carcinogen, chloroform, 1,2-dichloroethylene, tetrachloroethane and chlorobenzene. Plastic Dangers Health: Neural and behavioural effects, genetic damage, hormone disrupter, female reproductive problems, enlargement of reproductive organs, effects child growth, insulin resistance, inflammation and heart disease. Foetus exposure is linked to breast cancer as an adult. Detected in 93% of urine samples, highest rate present in children and infants due to objects being put in their mouth e.g. dummies, baby bottles. Detected in breast milk, blood of pregnant women. Leaching: Heating releases more toxins than room temperature. Strong cleaners increase leaching rate. Offgasses VOCsRecyclable: Can be downcycled into lower grade products or mixed with virgin materials. Products: CDs, refillable milk bottles, plastic utensils, drinking glasses, tin can lining, microwave dishes, disposable water bottles, refillable water bottles, food storage containers. Epoxy resins are used to line metal products such as canned foods, bottle tops, and water supply pipes. Alternatives: BPA free plastic, ‘Tritan copolyester’

Polyurethane (PU) Not categorised in the original resin identification system. Highly flammable and highly toxicBuilding block: Organic compounds containing carboxyl groups, polyols and diisocyanates.

Additives: Stabilisers, foamed products contain chemical catalysts, surfactants, emulsifiers, pigments, formaldehyde, benzene, toluene and organotin compounds. Plastic Dangers Health: Incineration releases hazardous chemicals; isocyanates, carbon dioxide, hydrogen cyanide, PAHs and dioxins. Hazardous by-products; phosgene, isocyanates, toluene, diamines, and methylene chloride gas, CFCs (both ozone-depleting), halogenated flame retardants and pigments. Leaching: Documented as safe according to guidelines. Offgasses VOCs Products: Insulation, soft foam, mattresses, surface coatings, carpet, underlay, car interiors, sealants, lining, adhesives, ceiling installations, flooring, mouldings, moulded furniture. Recyclable: YesAlternatives: Now include 20% soy based foam (non toxic, non fossil fuel, renewable material, soy foam is not biodegradable), the remaining 80% is made of PU. Spray Polyurethane Foam (SPF) used for building insulation is not known to contain formaldehyde, ozone depleting chemicals or leach into the air or earth (studies ongoing). A new modified polyurethane plastic has been developed that sinks to the sea bottom and degrades in sea water in 20 days (similar to dissolvable stitches). This combats the damage to marine life from marine waste.

Acrylonitrile-Butadiene-Styrene (ABS) Not categorised in the original resin identification system. ABS is a plastic resin, hard, impervious and resilient. Good heat, impact and chemical resistance. Degrades when exposed to acetone. Building block: Acrylonitrile, butadiene, styrenePlastic Dangers Health: Highly toxic in vapour and liquid form, all three substances are associated carcinogens. Leaching: Leaches into the body through the skin and inhalation. Offgasses VOCsProducts: Guttering, plumbing pipes, drainage pipes, car bumpers, electronic equipment casesRecyclable: YesRecyclable products: Downcycled into lesser grade products e.g. ground into flakes and processed into casing, garden furniture

Melamine (thermosetting plastic)

Not categorised in the original resin identification system. Fire resistant, fire barrier, versatile, stable, easy to mould when warm, cured by cool temperatures. Building block: Melamine, formaldehyde, ureaPlastic Dangers Health: Recorded as the cause of pet death through food contamination (wheat gluten) with symptoms of renal failure. Leaching: Dishware not suited to high temperatures as begins to break down. Products: Floor and wall tiles, fire retardant fabrics and upholstery, white boards, commercial filters, foam, Formica heat resistant worktop, mixed with composite materials, splashbackRecyclable: Difficult to recycle, decomposes with heat exposure

Biodegradable plastics are plastics that will decompose in natural aerobic (composting) and anaerobic (landfill) environments. Biodegradation of plastics can be achieved by enabling microorganisms in the environment to metabolize the molecular structure of plastic films to produce an inert humus-like material that is less harmful to the environment. They may be composed of either bioplastics, which are plastics whose components are derived from renewable raw materials, or petroleum-based plastics which utilize an additive. The use of bio-active compounds compounded with swelling agents ensures that, when combined with heat and moisture, they expand the plastic's molecular structure and allow the bio-active compounds to metabolize and neutralize the plastic.

Biodegradable plastics typically are produced in two forms: injection molded (solid, 3D shapes), typically in the form of disposable food service items, and films, typically organic fruit packaging and collection bags for leaves and grass trimmings, and agricultural mulch.

Scientific definitions of biodegradable plastic

In the United States, ASTM International is the authoritative body for defining biodegradable standards. The specific subcommittee responsibility for overseeing these standards falls on the Committee D20.96 on Environmentally Degradable Plastics and Biobased Products [1]. The current ASTM standards are defined as standard specifications and standard test methods. Standard specifications create a pass or fail scenario whereas standard test methods identify the specific testing parameters for facilitating specific biodegradable tests on plastics.

Currently, there are three such ASTM standard specifications which mostly address biodegradable plastics in composting type environments, the ASTM D6400-04 Standard Specification for Compostable Plastics,[2] ASTM D6868 - 03 Standard Specification for Biodegradable Plastics Used as Coatings on Paper and Other Compostable Substrates,[3] and the ASTM D7081 - 05 Standard Specification for Non-Floating Biodegradable Plastics in the Marine Environment.[4]

Currently the most accurate standard test method for anaerobic environments is the ASTM D5511 - 02 Standard Test Method for Determining Anaerobic Biodegradation of Plastic Materials Under High-Solids Anaerobic-Digestion Conditions.[5] Another standard test method for testing in anaerobic environments is the ASTM D5526 - 94(2002) Standard Test Method for Determining Anaerobic Biodegradation of Plastic Materials Under Accelerated Landfill Conditions,[6] this test has proven extremely difficult to perform.

The current California legislation AB 1972 ensures accurate environmental advertising of plastics by allowing only the use of terms that can be verified by an American Society for Testing Materials (ASTM) standard specification. This legislation does not include ASTM standard test methods. The two ASTM standard specifications which are used in the legislation are ASTM D6400 and D7081. Products passing these ASTM specifications can use the term compostable on the product label.[7]

[edit] Environmental benefits of biodegradable plastics depend upon proper disposal

Biodegradable plastics are not a panacea, however. Some critics claim that a potential environmental disadvantage of certified biodegradable plastics is that the carbon that is locked up in them is released into the atmosphere as a greenhouse gas. However, biodegradable plastics from natural materials, such as vegetable crop derivatives or animal products, sequester CO2 during the phase when they're growing, only to release CO2 when they're decomposing, so there is no net gain in carbon dioxide emissions[citation needed].

However, certified biodegradable plastics require a specific environment of moisture and oxygen to biodegrade, conditions found in professionally managed composting facilities. There is much debate about the total carbon, fossil fuel and water usage in processing biodegradable plastics from natural materials and whether they are a negative impact to human food supply. Traditional plastics made from non-renewable fossil fuels lock up much of the carbon in the plastic as opposed to being utilized in the processing of the plastic. The carbon is permanently trapped inside the plastic lattice, and is rarely recycled.

There is concern that another greenhouse gas, methane, might be released when any biodegradable material, including truly biodegradable plastics, degrades in an anaerobic (landfill) environment. Methane production from these specially managed landfill environments are typically captured and burned to negate the release of methane in the environment. Some landfills today capture the methane biogas for use in clean inexpensive energy. Of course, incinerating non-biodegradable plastics will release carbon dioxide as well. Disposing of biodegradable plastics made from natural materials in anaerobic (landfill) environments will result in the plastic lasting for hundred of years.

The US EPA has mandated strict standards for landfill design and construction to prevent biodegradation in a landfill in the first place. The intentional production of methane from landfills is, therefore, the rare exception and not the rule for most municipal solid waste.

It is also possible that bacteria will eventually develop the ability to degrade plastics. This has already happened with nylon: two types of nylon eating bacteria, Flavobacteria and Pseudomonas, were found in 1975 to possess enzymes (nylonase) capable of breaking down nylon. While not a solution to the disposal problem, it is likely that bacteria will evolve the ability to use other synthetic plastics as well. In 2008, a 16-year-old boy reportedly isolated two plastic-consuming bacteria.[8]

The latter possibility was in fact the subject of a cautionary novel by Kit Pedler and Gerry Davis (screenwriter), the creators of the Cybermen, re-using the plot of the first episode of their Doomwatch series. The novel, Mutant 59: The Plastic Eater, written in 1971, is the story of what could happen if a bacterium were to evolve—or be artificially cultured—to eat plastics, and be let loose in a major city.

[edit] Mechanisms

Materials such as a polyhydroxyalkanoate (PHA) biopolymer are completely compostable in an industrial compost facility. Polylactic acid (PLA) is another 100% compostable biopolymer which can fully degrade above 60C in an industrial composting facility. Fully biodegradable plastics are more expensive, partly because they are not widely enough produced to achieve large economies of scale.

Certain additives when added to conventional plastics attract the microbes to the molecular structure by allowing the hydrocarbons to be sensed once again by microbial colonies. When oil is in the ground, the microbes attach themselves onto the hydrocarbons consuming the oil and creating natural gas, 50% of which is methane gas. When the oil is cracked 4% is used for the plastic industry, if the plastic industry did not use this 4% the 4% would be considered waste and be thrown away or removed and dumped into a waste disposal facility, another 4% is used in the generation of your consumer product. During this phase of cracking the organic compound which attracts the microbes to the molecular structure of the plastic is burnt out. The organic compound which is burnt out and other proprietary compounds which increase quorum sensing of the microbes and pH balance for the microbes are placed into the molecular structure of the plastic, to create a plastic product that can biodegrade 100 times faster than normal plastic.

[edit] Advantages and disadvantages

Under proper conditions biodegradable plastics can degrade to the point where microorganisms can metabolise them.

Degradation of oil-based biodegradable plastics may release previously stored carbon as carbon dioxide. Starch-based bioplastics produced from sustainable farming methods can be almost carbon neutral but could have a damaging effect on soil, water usage and quality, and result in higher food prices.

[edit] Environmental concerns; benefits

Over 200 million tons of plastic are manufactured annually around the world, according to the Society of Plastics Engineers.[9][unreliable source?] Of those 200 million tons, 26 million are manufactured in the United States. The EPA reported in 2003 that only 5.8% of those 26 million tons of plastic waste are recycled, although this is increasing rapidly.

Much of the reason for disappointing plastics recycling goals is that conventional plastics are often commingled with organic wastes (food scraps, wet paper, and liquids), making it difficult and impractical to recycle the underlying polymer without expensive cleaning and sanitizing procedures.

On the other hand, composting of these mixed organics (food scraps, yard trimmings, and wet, non-recyclable paper) is a potential strategy for recovering large quantities of waste and dramatically increase community recycling goals. Food scraps and wet, non-recyclable paper comprises 50 million tons of municipal solid waste.[10]. Biodegradable plastics can replace the non-degradable plastics in these waste streams, making municipal composting a significant tool to divert large amounts of otherwise nonrecoverable waste from landfills.

If even a small amount of conventional plastics were to be commingling with organic materials, the entire batch of organic waste is "contaminated" with small bits of plastic that spoil prime-quality compost humus. Composters, therefore, will not accept mixed organic waste streams unless they are completely devoid of nondegradable plastics. So, because of a relatively small quantity of nondegradable plastics, a significant waste disposal strategy is stalled.

However, proponents of biodegradable plastics[who?] argue that these materials offer a solution to this problem. Certified biodegradable plastics combine the utility of plastics (lightweight, resistance, relative low cost) with the ability to completely and fully biodegrade in a compost facility. Rather than worrying about recycling a relatively small quantity of commingled plastics, these proponents argue that certified biodegradable plastics can be readily commingled with other organic wastes, thereby enabling composting of a much larger position of nonrecoverable solid waste. Commercial composting for all mixed organics then becomes commercially viable and economically sustainable. More municipalities can divert significant quantities of waste from overburdened landfills since the entire waste stream is now biodegradable and therefore easier to process.

The use of biodegradable plastics, therefore, is seen as an enabler for the complete recovery of large quantities of municipal sold waste (via aerobic composting) that were are heretofore unrecoverable by other means except land filling or incineration.

[edit] Confusion over proper definition of terms

Until recently there were few legal standards regarding marketing claims surrounding the use of the term 'biodegradable'. In 2007, the state of California passed regulation banning companies from claiming their products are biodegradable without proper scientific certification from a third-party laboratory.

The Federal Court of Australia declared on March 30, 2009 that a director of a company that manufactured 'biodegradable' disposable diapers (who also approved the company's advertising) had been knowingly making false and misleading claims about biodegradability[11].

In June 2009, the Federal Trade Commission charged two companies with making unsupported marketing claims regarding biodegradability.[12]

[edit] Energy costs for production

Various researchers have undertaken extensive life cycle assessments of biodegradable polymers to determine whether these materials are more energy efficient than polymers made by conventional fossil fuel-based means. Research done by Gerngross, et al. estimates that the fossil fuel energy required to produce a kilogram of polyhydroxyalkanoate (PHA) is 50.4 MJ/kg,[13][14] which coincides with another estimate by Akiyama, et al.[15], who estimate a value between 50-59 MJ/kg. This information does not take into account the feedstock energy, which can be obtained from non-fossil fuel based methods. Polylactide (PLA) was estimated to have a fossil fuel energy cost of 54-56.7 from two sources[16][17], but recent developments in the commercial production of PLA by NatureWorks has eliminated some dependence fossil fuel based energy by supplanting it with wind power and biomass-driven strategies. They report making a kilogram of PLA with only 27.2 MJ of fossil fuel-based energy and anticipate that this number will drop to 16.6 MJ/kg in their next generation plants. In contrast, polypropylene and high density polyethylene require 85.9 and 73.7 MJ/kg respectively[18], but these values include the embedded energy of the feedstock because it is based on fossil fuel.

Gerngross reports a 2.65 total fossil fuel energy equivalent (FFE) required to produce a single kilogram of PHA, while polypropylene only requires 2.2 kg FFE[19]. Gerngross assesses that the decision to proceed forward with any biodegradable polymer alternative will need to take into account the priorities of society with regard to energy, environment, and economic cost.

Furthermore, it is important to realize the youth of alternative technologies. Technology to produce PHA, for instance, is still in development today, and energy consumption can be further reduced by eliminating the fermentation step,[20] or by utilizing food waste as feedstock.[21] The use of alternative crops other than corn, such as sugar cane from Brazil, are expected to lower energy requirements- manufacturing of PHAs by fermentation in Brazil enjoys a favorable energy consumption scheme where bagasse is used as source of renewable energy.[22]

Many biodegradable polymers that come from renewable resources (i.e., starch-based, PHA, PLA) also compete with food production, as the primary feedstock is currently corn. For the US to meet its current output of plastics production with BPs, it would require 1.62 square meters per kilogram produced[23]. While this space requirement could be feasible, it is always important to consider how much impact this large scale production could have on food prices and the opportunity cost of using land in this fashion versus alternatives.

Biodegradable bags are bags made from materials that are able to decompose under specified conditions of light, moisture, and oxygen.[1] Every year approximately 500 billion to 1 trillion plastic bags are used worldwide.[2] Often composting conditions or exposure to sun, moisture,

and oxygen are needed: degradation is slow in landfills. Many stores and companies are beginning to use different types of biodegradable bags to comply with perceived environmental benefits.[3][4]

Plastic bags can be made Oxo-biodegradable by being manufactured from normal polymer with an additive which causes accelerated breakdown of the molecular chains, and subsequent bioassimilation; or "Hydro-biodegradable" by being manufactured from vegetable-based materials.

The Trade Association for the Oxo-biodegradable plastics industry is the Oxo-biodegradable Plastics Association (www.biodeg.org), which will certify products tested according to ASTM D6954 or (as from 1st Jan 2010) UAE 5009:2009

The Trade Associations for the Hydro-biodegradable plastics industry are the Biodegradable Products Institute] (BPI) "European Bioplastics" and SPIBioplastics Council" Plastics are certified as biodegradable under composting conditions in the United States if they comply with ASTM D6400, and in Europe EN13432.

The pros and cons of these two types of plastics will be found on the websites of the Trade Associations as above.

The Standards appropriate to hydro-biodegradable plastics are not appropriate for oxo-biodegradable plastics and vice-versa

[edit] Companies

Different companies use different kinds of biodegradable bags. Many stores use biodegradable bags. Multinational baking giant Grupo Bimbo SAB de CV of Mexico City claims to have been the first to make "Oxo Biodegradable metalized polypropylene snack bag".[5] In addition to that, a company named "Doo Bandits" has created biodegradable bags used for picking up dog waste.[6] The Supermarket Chain Aldi Süd in Germany offers biodegradable Ecovio bags. Ecoflex bags are flexible, tear-resistant, waterproof, and suitable for printing. It gives the bags renewable raw material, making them biodegradable.[7]

All of these examples show where companies have claimed biodegradable products without qualification of how long, conditions required, end state results, or weither the residue contains harmful by products as outlined in the pass/fail ASTM D6400 standard. In most cases, without clarification that these products require composting conditions to achieve endstate, the products will be placed in traditional landfills and there will be no environmental benefits and no improvement in degradation of the product.

[edit] Materials

Most bags are made from plastic combined with corn-based materials.[citation needed] Biodegradable plastic bags require more plastic per bag, because the material is not as strong.[citation needed] Many bags are also made from paper, organic materials, or polycaprolactone.[2][3][8]

"The public looks at biodegradable as something magical," even though the term is mostly meaningless, according to Ramani Narayan, a chemical engineer at Michigan State University in East Lansing, and science consultant to the Biodegradable Plastics Institute. "This is the most used and abused and misused word in our dictionary right now. Simply calling something biodegradable and not defining in what environment it is going to be biodegradable and in what time period it is going to degrade is very misleading and deceptive." In the Great Pacific Garbage Patch, biodegradable plastics break up into small pieces that can more easily enter the food chain by being consumed." [9]

[edit] Recycling

In- plant scrap can often be recycled but post-consumer sorting and recycling is difficult. Many biodegradable polymers have the potential to contaminate the recycling of other more common polymers. Degradable bags need to be kept separate from the normal recycling stream. SPI Resin identification code 7 is applicable.

[edit] Marketing Qualification

Since many of these plastics require access to sunlight, oxygen, or lengthy periods of time to achieve degradation or biodegradation the Federal Trade Commission's, GUIDES FOR THE USE OF ENVIRONMENTAL MARKETING CLAIMS, commonly called the "green guide"[10] require proper marking of these products to show their performance limits.

The FTC provides an example:

Example 1: A trash bag is marketed as “degradable,” with no qualification or other disclosure. The marketer relies on soil burial tests to show that the product will decompose in the presence of water and oxygen. The trash bags are customarily disposed of in incineration facilities or at sanitary landfills that are managed in a way that inhibits degradation by minimizing moisture and oxygen. Degradation will be irrelevant for those trash bags that are incinerated and, for those disposed of in landfills, the marketer does not possess adequate substantiation that the bags will degrade in a reasonably short period of time in a landfill. The claim is therefore deceptive

Since there are no pass fail tests for "biodegradable" plastic bags manufactures must print on the product the environmental requirements for biodegradation to take place, time frame and end results in order to be within US Trade Requirements.

Our whole world seems to be wrapped in plastic. Almost every product we buy, most of the food we eat and many of the liquids we drink come encased in plastic. In Australia around 1 million tonnes of plastic materials are produced each year and a further 587,000 tonnes are imported.

Packaging is the largest market for plastics, accounting for over a third of the consumption of raw plastic materials – Australians use 6 billion plastic bags every year!

Plastic packaging provides excellent protection for the product, it is cheap to manufacture and seems to last forever. Lasting forever, however, is proving to be a major environmental problem. Another problem is that traditional plastics are manufactured from non-renewable resources – oil, coal and natural gas.

Plastics that break down

In an effort to overcome these shortcomings, biochemical researchers and engineers have long been seeking to develop biodegradable plastics that are made from renewable resources, such as plants.

The term biodegradable means that a substance is able to be broken down into simpler substances by the activities of living organisms, and therefore is unlikely to persist in the environment. There are many different standards used to measure biodegradability, with each country having its own. The requirements range from 90 per cent to 60 per cent decomposition of the product within 60 to 180 days of being placed in a standard composting environment.

The reason traditional plastics are not biodegradable is because their long polymer molecules are too large and too tightly bonded together to be broken apart and assimilated by decomposer organisms. However, plastics based on natural plant polymers derived from wheat or corn starch have molecules that are readily attacked and broken down by microbes.

Plastics can be produced from starch

Starch is a natural polymer. It is a white, granular carbohydrate produced by plants during photosynthesis and it serves as the plant's energy store. Cereal plants and tubers normally contain starch in large proportions. Starch can be processed directly into a bioplastic but, because it is soluble in water, articles made from starch will swell and deform when exposed to moisture, limiting its use. This problem can be overcome by modifying the starch into a different polymer. First, starch is harvested from corn, wheat or potatoes, then microorganisms transform it into lactic acid, a monomer. Finally, the lactic acid is chemically treated to cause the molecules of lactic acid to link up into long chains or polymers, which bond together to form a plastic called polylactide (PLA).

PLA can be used for products such as plant pots and disposable nappies. It has been commercially available since 1990, and certain blends have proved successful in medical implants, sutures and drug delivery systems because of their capacity to dissolve away over time. However, because PLA is significantly more expensive than conventional plastics it has failed to win widespread consumer acceptance.

Plastics can also be produced by bacteria

Another way of making biodegradable polymers involves getting bacteria to produce granules of a plastic called polyhydroxyalkanoate (PHA) inside their cells. Bacteria are simply grown in culture, and the plastic is then harvested. Going one step further, scientists have taken genes from this kind of bacteria and stitched them into corn plants, which then manufacture the plastic in their own cells.

What’s the cost?

Unfortunately, as with PLA, PHA is significantly more expensive to produce and, as yet, it is not having any success in replacing the widespread use of traditional petrochemical plastics.

Indeed, biodegradable plastic products currently on the market are from 2 to 10 times more expensive than traditional plastics. But environmentalists argue that the cheaper price of traditional plastics does not reflect their true cost when their full impact is considered. For example, when we buy a plastic bag we don’t pay for its collection and waste disposal after we use it. If we added up these sorts of associated costs, traditional plastics would cost more and biodegradable plastics might be more competitive (Box 1: Life cycle analysis).

Biodegradable and affordable

If cost is a major barrier to the uptake of biodegradable plastics, then the solution lies in investigating low-cost options to produce them. In Australia, the Cooperative Research Centre (CRC) for International Food Manufacture and Packaging Science is looking at ways of using basic starch, which is cheap to produce, in a variety of blends with other more expensive biodegradable polymers to produce a variety of flexible and rigid plastics. These are being made into ‘film’ and ‘injection moulded’ products such as plastic wrapping, shopping bags, bread bags, mulch films and plant pots.

Mulch film from biodegradable plastics

The CRC has developed a mulch film for farmers. Mulch films are laid over the ground around crops, to control weed growth and retain moisture. Normally, farmers use polyethylene black plastic that is pulled up after harvest and trucked away to a landfill (taking with it topsoil humus that sticks to it). However, field trials using the biodegradable mulch film on tomato and capsicum crops have shown it performs just as well as polyethylene film but can simply be ploughed into the ground after harvest. It’s easier, cheaper and it enriches the soil with carbon.

Pots you can plant

Another biodegradable plastic product is a plant pot produced by injection moulding. Gardeners and farmers can place potted plants directly into the ground, and forget them. The pots will break down to carbon dioxide and water, eliminating double handling and recycling of conventional plastic containers.

Different polymer blends for different products

Depending on the application, scientists can alter polymer mixtures to enhance the properties of the final product. For example, an almost pure starch product will dissolve upon contact with water and then biodegrade rapidly. By blending quantities of other biodegradable plastics into the starch, scientists can make a waterproof product that degrades within 4 weeks after it has been buried in the soil or composted.

Landfill sites aren't compost heaps

To maximise the benefit of the new bioplastics we’ll have to modify the way we throw away our garbage – to simply substitute new plastics for old won’t be saving space in our landfills.

Although there is a popular misconception that biodegradable materials break down in landfill sites, they don't. Rubbish deposited in landfill is compressed and sealed under tonnes of soil. This minimises oxygen and moisture, which are essential requirements for microbial decomposition. For biodegradable plastics to effectively decompose they need to be treated like compost.

Composting the packaging with its contents

Compost may be the key to maximising the real environmental benefit of biodegradable plastics. One of the big impediments to composting our organic waste is that it is so mixed up with non-degradable plastic packaging that it is uneconomic to separate them. Consequently, the entire mixed waste-stream ends up in landfill. Organic waste makes up almost half the components of landfill in Australia.

By ensuring that biodegradable plastics are used to package all our organic produce, it may well be possible in the near future to set up large-scale composting lines in which packaging and the material it contains can be composted as one. The resulting compost could be channelled into plant production, which in turn might be redirected into growing the starch to produce more biodegradable plastics.

An Olympic effort – recycling 76 per cent of waste

For anyone who thinks such schemes aren’t feasible, you only have to look at the recycling success of the Sydney Olympics to see that where there’s a will, there’s a way. More than 660 tonnes of waste was generated each day at its many venues. Of this, an impressive 76 per cent was collected and recycled. Part of this success was due to the use of biodegradable plastics used in the packaging of fast food, making the composting of food scraps an economic proposition as it eliminated the need for expensive separation of packaging waste prior to processing.

With intelligent use, these new plastics have the potential to reduce plastic litter, decrease the quantities of plastic waste going into landfills and increase the recycling of other organic components that would normally end up in landfills.

What is biodegradable plastic made of?they may be composed of either bioplastics, which are plastics whose components are derived from renewable raw materials, or petroleum-based plastics. The use of bio-active compounds compounded with swelling agents ensures that, when combined with heat and moisture, they expand the plastic's molecular structure and allow the bio-active compounds to metabolise and neutralize the plastic. Biodegradation of plastics can be achieved by enabling microorganisms in the environment to metabolize the molecular structure of plastic films to produce an inert humus-like material that is less harmful to the environment.

Bioplastics (also called organic plastics) are a form of plastics derived from renewable biomass sources, such as vegetable oil, corn starch, pea starch or microbiota.

Degradation of petroleum-based biodegradable plastics may release of previously stored carbon as carbon dioxide. Materials such as polyhydroxyalkanoate (PHA) biopolymer are completely biodegradable. Fully biodegradable plastics are more expensive, partly because they are not widely enough produced to achieve large economies of scale.

Where can we put all those plastics?Plastics and recycling have a complicated relationship. All plastics are technically recyclable. But in the real world, plastics recycling...

Recycling resources

Common plastics used in packaging:

• Symbol #1 PETE or PET: Polyethylene terephthalate. Main use: Beverage bottles.

• Symbol #2 HDPE: High-density polyethylene. Main uses: Bottles, bags.

• Symbol #3 V or PVC: Polyvinyl chloride, or vinyl. Main uses: Bags, wraps.

• Symbol #4 LDPE: Low-density polyethylene. Main use: Bags.

• Symbol #5 PP: Polypropylene. Main uses: Food tubs, caps.

• Symbol #6 PS: Polystyrene (often called Styrofoam). Main uses: Food trays, packing.

• Symbol #7 Other: Usually polycarbonate, or bio-based plastics. Main use: Bottles.

Plastics and recycling have a complicated relationship. All plastics are technically recyclable. But in the real world, plastics recycling has many limitations.

Plastics recycling seems to confuse and frustrate consumers more than any other type of recycling. Plastic products and packaging permeate our society, and most plastics come from fossil fuels. So plastic recycling does matter. Here's what you should know:

• Plastics lag behind. Nationally, less than 6 percent of all waste plastic gets recycled, compared with recycling rates of 50 percent for paper, 37 percent for metals and 22 percent for glass, says the U.S. Environmental Protection Agency.

Plastic bottles have the highest recycling level among consumer plastics, at 24 percent, according to the American Chemistry Council. Polyvinyl chloride, a plastic under scrutiny because of health concerns, has a recycling rate below 1 percent, says Consumers Union.

Reasons for low national plastics recycling rates include the complexity of sorting and processing, unfavorable economics and consumer confusion about which plastics can be recycled.

Unlike aluminum cans or cardboard boxes, plastic containers seldom get recycled back into new containers. Instead, waste plastic must be "downcycled" into secondary recycled products such as textiles and composite lumber for decking.

• Logos can mislead. In 1988, the plastics industry introduced logos and numbers for plastics used in packaging (see box). The stated intent was to make it easier to identify plastics for recycling. Not surprisingly, some consumers see the familiar "chasing-arrows" recycling logo on a plastic item and assume they can recycle it. But many plastics emblazoned with the logo — such as big chunks of polystyrene (Styrofoam) packing material or lids for plastic containers — are not accepted by residential recycling programs, due to high processing costs and lack of markets.

Recycling resources

Common plastics used in packaging:

• Symbol #1 PETE or PET: Polyethylene terephthalate. Main use: Beverage bottles.

• Symbol #2 HDPE: High-density polyethylene. Main uses: Bottles, bags.

• Symbol #3 V or PVC: Polyvinyl chloride, or vinyl. Main uses: Bags, wraps.

• Symbol #4 LDPE: Low-density polyethylene. Main use: Bags.

• Symbol #5 PP: Polypropylene. Main uses: Food tubs, caps.

• Symbol #6 PS: Polystyrene (often called Styrofoam). Main uses: Food trays, packing.

• Symbol #7 Other: Usually polycarbonate, or bio-based plastics. Main use: Bottles.

To add to the confusion, certain plastics with the same number cannot be recycled together because they require a different heating and molding process.

Several Seattle-area recycling programs now tell residents to ignore the numbers. Recycling programs often keep things simple by asking for "all plastic bottles" or "plastic bottles and round dairy tubs," for example.

Always check with your program to confirm the materials it accepts.

• Lids and caps go in the garbage. No area recycling programs accept plastic caps or lids. Leaving the cap on a plastic bottle also makes collection and processing more difficult, because the bottle cannot easily be flattened and takes up more space. But you don't need to remove labels or the small plastic rings on the necks when you recycle plastic bottles.

• The Others don't mix well. Plastic containers labeled "Other," or #7, are usually polycarbonate. But an increasing number is made from new bioplastics, such as corn-based polylactic acid, or PLA. Although bioplastics will not easily degrade in a modern landfill, municipal composting programs could some day accept them. Keep all #7 containers, including PLA, out of your recycling bin.

• Bags have a future. A strong recycling market exists for plastic bags. Some residential recycling programs accept "bags of bags," but the recycling industry can deal with them better if you take them back to grocery-store collection bins. Never put a loose bag in your recycling bin; it can clog equipment at the sorting plant. Don't recycle plastic bags marked "biodegradable" unless specifically approved by the recycler.

• Reducing and reusing trump recycling. Save money and conserve resources with a reusable water bottle (metal and #2 or #4 plastic are best). Single-use beverage bottles, usually #1, are not designed for long-term reuse.

Reduce the number of plastic bags you accept, and reuse them, or use durable tote bags.

Polystyrene packing peanuts cannot easily be recycled, but some shipping stores accept them for reuse.

Plastic plant pots also are not normally recycled, but a few area nurseries take them back to use again.

Biodegradable Plastic

The quest for impermanence

In the mid-1990s, a certain mail-order computer retailer announced that it was abandoning Styrofoam (polystyrene) packing peanuts in its shipments and switching to environmentally friendly cornstarch peanuts instead. The new filler material, they explained, was not merely biodegradable, it would dissolve almost instantly in water. Some of my coworkers and I wondered if that meant you could eat them too. So, naturally, when our next order arrived from that company, the first thing we did was to pop the cornstarch peanuts in our mouths. All right, in retrospect, I suppose that was a bit stupid. It did not cause any ill effects as far as I can tell, but still…who knows where that cornstarch has been? So I do not recommend that you try this yourself. Nevertheless, we’d proven that this new packing material did, as advertised, dissolve quite readily, and we were all happy that we’d no longer drown in a sea of Styrofoam.

Remarkably, even though cornstarch packing peanuts are much more common today, most of the packages I get in the mail are still filled with Styrofoam. I suppose the charitable view is that I’m watching recycling in action: no doubt these very pellets have been used countless times before, and (if I keep with the program) will be used countless times again. But even if true, that’s somehow unsatisfying. I really don’t want the burden of storing (or recycling) the filler from every box I get. I’d like it all to go away—preferably, in some responsible manner.

Having a Breakdown

Resistance to decomposition is often a virtue; you don’t want, say, your garbage can to disintegrate in the rain. But for items that are intended to be used only briefly, this robustness can be a problem. Hundreds of years from now, empty plastic bottles—not to mention discarded electronic devices, toys, and everything else—will still be pretty much intact deep in landfills all over the world. And although recycling helps considerably, it’s simply not practical or reasonable to expect that no recyclable goods will ever end up in the trash. So the next-best thing—and, in many instances, the very best thing—is plastic that will decompose.

But allow me to digress for a moment. Words like “decompose,” “disintegrate,” “degrade,” and “biodegrade” do not all mean the same thing. Suppose you put a piece of plastic in a compost heap and found no visible trace of it six months later—does that mean it has biodegraded? And if so, can we safely say we’re talking about an environmentally safe product? The answer to both questions is “not necessarily.” Some so-called “biodegradable” plastics, for instance, are made of a blend of starch derivatives and conventional petroleum-based polymers. The action of bacteria in warm, moist soil breaks down the starches in these materials, but leaves countless tiny particles of plastic that have a mass only slightly less than that of the original product. And all those parts that don’t break down continue taking up space without contributing any nutrients to the soil—in fact, they may actually contribute toxins. So what we’re looking for in a truly “green” plastic is one that can either decompose completely via microbial digestion (into such products as water and carbon dioxide), or at the very least, leave only inert substances behind.

Natural Wonders

The thing is, this is generally not in the nature (so to speak) of synthetic polymers. The interesting solutions, therefore, are largely to be found in biopolymers, a class of materials that look, feel, and act like the plastics we all know and love, but which, owing to their natural sources, can also serve as food for bacteria. Products made directly from cornstarch, other starches, or cellulose certainly fit that description. And such materials, which are used not only for packing peanuts but for things like fast-food containers, do show a great deal of promise. But if you’re looking for something bacteria might like to eat, how about the food they make themselves?

Many different kinds of bacteria (and other organisms, for that matter) create a substance known as polyhydroxybutyrate, or PHB, that they store as an energy source in much the same way humans store fat. PHB, it turns out, is a rather versatile plastic. It can be produced in quantity quite quickly simply by feeding sugar to the right kinds of bacteria in what amounts to a fermentation process; it can also be produced by genetically modified plants (including a type of potato). Because it is, in fact, a bacterial food product, it’s completely biodegradable. Another often-mentioned biopolymer is polylactic acid, or PLA, made from lactic acid—which, in turn, is produced by the fermentation of cornstarch.

Surprisingly enough, a few petroleum-based synthetic polymers, such as polycaprolactone, can also decompose by way of microbial action. But the appeal of using plant derivatives as the source of plastics is that they’re renewable: you can “grow” your plastics in a field or “brew” them in a vat—and make more whenever you want. At the moment, biopolymers such as PHB and PLA are relatively expensive to produce, and less flexible than many synthetic plastics. And,

of course, conventional plastics are heavily entrenched in many industries. But perhaps in the future, we’ll toss all our bottles and used packing materials into the same bin as our trash—without guilt. Wouldn’t that be amazing? —Joe Kissell

Dear EarthTalk: Is it true that nothing really “biodegrades” in a landfill? — Laura, via e-mail

Organic substances “biodegrade” when they are broken down by other living organisms (such as enzymes and microbes) into their constituent parts, and in turn recycled by nature as the building blocks for new life. The process can occur aerobically (with the aid of oxygen) or anaerobically (without oxygen). Substances break down much faster under aerobic conditions, as oxygen helps break the molecules apart.

Landfills Too Tightly Packed for Most Trash to BiodegradeMost landfills are fundamentally anaerobic because they are compacted so tightly, and thus do not let much air in. As such, any biodegradation that does take place does so very slowly.

“Typically in landfills, there’s not much dirt, very little oxygen, and few if any microorganisms,” says green consumer advocate and author Debra Lynn Dadd. She cites a landfill study conducted by University of Arizona researchers that uncovered still-recognizable 25-year-old hot dogs, corncobs and grapes in landfills, as well as 50-year-old newspapers that were still readable.

Processing May Inhibit BiodegradationBiodegradable items also may not break down in landfills if the industrial processing they went through prior to their useful days converted them into forms unrecognizable by the microbes and enzymes that facilitate biodegradation. A typical example is petroleum, which biodegrades easily and quickly in its original form: crude oil. But when petroleum is processed into plastic, it is no longer biodegradable, and as such can clog up landfills indefinitely.

Some manufacturers make claims that their products are photodegradable, which means that they will biodegrade when exposed to sunlight. A popular example is the plastic “polybag” in which many magazines now arrive protected in the mail. But the likelihood that such items will be exposed to sunlight while buried dozens of feet deep in a landfill is little to none. And if they do biodegrade at all, it is only likely to be into smaller pieces of plastic.

Landfill Design and Technology May Enhance BiodegradationSome landfills are now being designed to promote biodegradation through the injection of water, oxygen, and even microbes. But these kinds of facilities are costly to create and, as a result, have not caught on. Another recent development involves landfills that have separate sections for compostable materials, such as food scraps and yard waste. Some analysts believe that as much as 65 percent of the waste currently sent to landfills in North America consists of such “biomass” that biodegrades rapidly and could generate a new income stream for landfills: marketable soil.

Reduce, Reuse, Recycle is Best Solution for LandfillsBut getting people to sort their trash accordingly is another matter entirely. Indeed, paying heed to the importance of the environmental movement’s “Three Rs” (Reduce, Reuse, Recycle!) is likely the best approach to solving the problems caused by our ever-growing piles of trash. With

landfills around the world reaching capacity, technological fixes are not likely to make our waste disposal problems go away.

Biodegradable plastics take time to completely dissolve

If plastic is made to be biodegradable, then won't the plastic forks and spoons we use dissolve in our mouth?

Ask your own question!

Plastics are indispensable to modern life. However, every year, more than 30 billion pounds of plastic wastes are generated by American consumers, clogging our landfills and polluting our landscape. Just to give you an idea of how much waste this is, if you dumped all of this plastic waste on the Cornell University football field, it would reach about 3 miles up into the sky! Therefore a significant amount of scientific work is directed at developing polymers that degrade in the environment into non-toxic materials.

These so-called biodegradable polymers degrade in natural environments by reacting with water and/or various bacteria. One everyday example where a biodegradable polymer has taken the place of conventional plastic is in the packing 'peanuts' that surround merchandise during shipping. In the past, these were made of a non-degradable polystyrene, but are now commonly made of a natural starch-based material. My guess is that you might have found that these new 'peanuts' are soluble in water, perhaps prompting you to ask your question.

Fortunately, there are a range of biodegradable plastics, each of which has its own rate of degradation. The key is to make the plastic degrade slower than the estimated lifetime of the object, yet fast enough that it doesn't persist in the environment. There are two promising plastics in this respect: polylactic acid (PLA) and polyhydroxybutryate (PHB).

PLA is currently being commercialized jointly by Dow and Cargill, and they plan to make a range of new plastic objects, such as the clam shells that are used in the fast-food industry.

PHB has previously been used in Europe. Shown below is a shampoo bottle made of PHB that was allowed to decompose in soil. As you can see, the plastic degrades over months, not minutes! Therefore, this would be an ideal plastic to make plastic utensils.

Hopefully biodegradable forks will be common in the near future. When they appear, don't worry -- you will be able to take your time eating with these forks!

“Biodegradable” plastic bags, is it really   green? 25 03 2010

  D2w Biodegradable Plastic is a true solution to irresponsible plastic waste disposalRecently I was reading an article that really shocked me - Then, after reasearching for the lies and truths, I would like to share this information and hopefully can get some comments on it.

NOT TRUESome people claimed that Plastic bags that are advertised as degradable and sold in many supermarkets may not be as environmentally friendly. Such bags usually use “oxo-degradable” plastics which include small amounts of additives to make them degrade faster.

The study said these plastics have an uncertain impact on the natural environment and are neither suitable for conventional recycling methods, because of the chemical additives, nor for composting.”As these plastics cannot be composted, the term “biodegradable’ can cause confusion,” Environment Minister Dan Norris said in a statement.

“We hope this research will discourage manufacturers and retailers from claiming that these materials are better for the environment than conventional plastics,” he added.

The above statement and study was executed out by Loughborough University and funded by the Department for Environment, Food and Rural Affairs.

*Source: http://uk.reuters.com/article/idUKTRE62B1GO20100312 (Reporting by Valle Aviles Pinedo; Editing by Steve Addison)

TRUEThe below report is the response to the above Loughborough Report on Oxo-Degradable Plastics From Symphony Environmental Technologies Plc

On 11th March the Department for the Environment and Rural Affairs (DEFRA) of the UK Government published a Report from Loughborough University entitled “Assessing the Environmental Impacts of Oxo-degradable Plastics Across their Life-cycle.”

A detailed response has been prepared by Symphony Environmental Technologies Plc., a British public company quoted on the London Stock Exchange, developing and supplying Oxo-biodegradable plastic technology under its d2w trademark in 92 countries worldwide. (And us, J-Trend Systems, is the authorized distributor of d2w in Asia)

 The Loughborough Report has confirmed that oxo-biodegradable plastics:        * Do degrade abiotically in a normal environment    * Do degrade abiotically under elevated temperatures in landfill    * Do biodegrade    * Do not emit methane even deep in landfill    * Are safe for food contact    * Contain no heavy metals       The report has also confirmed that:       * Pro-degradant additives are not harmful and have no negative      environmental impact in the production and use phase    * There is no evidence of bio-accumulation nor any harmful effect      on the environment    * There is no evidence of accumulation of pollutants    * There is no evidence that degradable plastics encourage littering

However, Symphony believes that the Report contains some very strange recommendations about oxo-biodegradable plastics in relation to recycling, composting, and other issues, which are not supported by the evidence.

The report was prepared by four members of staff at Loughborough, none of whom are professors, and none of whom is a specialist in oxo-biodegradable technology. They state that their recommendations are their own opinions, and that their views do not necessarily reflect DEFRA policy or opinions.

The Oxo-biodegradable plastics industry was not given a draft of the Report before publication nor asked for its views on the “Key Findings and Recommendations”. Symphony regard this as inappropriate.

For a full copy of the response document please see the attachment or go to http://www.d2w.net or http://www.biodeg.org

Leading international experts on oxo-biodegradable technology, Professor Gerald Scott, and Prof. Telmo Ojeda, have also commented – see http://www.biodeg.org

For videos of Symphony’s d2w plastic degrading see http://www.youtube.com/watch?v=i3TGqcpWJTM and http://www.youtube.com/watch?v=jbxEu04t7xE

 *Source: http://au.sys-con.com/node/1327890

As an authorized distributor for d2w additives in Asia, I would really love to conclude that: 

“d2wTM controlled-life plastic are products with proven oxo-biodegradable technology. Before d2wTM oxo-biodegradable plastic starts to degrade, it is as good as ordinary plastic for strength, sealability, printability, and clarity; when it starts to degrade, it does not release methan or

toxicity – withouting causing harm and disposal problem to the environment.”  

We all have basic understanding that ordinary plastic bags and packaging can take up to 400 years to degrade! When plastic bags are improperly discarded, they remain scattered in our bushes, our trees, on our roads, in our rivers and seas, killing live animals and causing great damage to the environment.

At least, we are confident to say that d2w biodegradable technology  is a great invention to prevent/cure irresponsible plastic waste disposal problem, because they are able to breakdown in any environement when oxygen is present. 

Oxo-biodegradable plastic products made with d2w technology are available in over 60 countries worldwide and are distributed in shops, supermarkets and retail stores who are committed to preserving the environment.

Biodegradable plastic bags carry more ecological harm than goodDecomposing bags sound environmentally friendly but they require a lot of energy to make, won't degrade in landfills and may leave toxic leftovers

Biodegradable plastic bags – as handed out by Tesco, the Co-op and once even sold by the Soil Association – must be good, surely? They have a magic ingredient that means they self-destruct after a few months, breaking up into tiny pieces made of simple molecules that bugs and fungi can happily munch up. Dozens of major corporations use them, including Pizza Hut, KFC, News international, Walmart and Marriott hotels.

But last week, the European Plastics Recyclers Association warned that they "have the potential to do more harm to the environment than good."

Technically what we are talking about here is "oxo-degradable" plastics. These are plastics made to degrade in the presence of oxygen and sunlight, thanks to the addition of tiny amounts of metals like cobalt, iron or manganese.

British manufacturers – headed by Symphony Technologies of Borehamwood – are at the sharp end of a revolution that could banish bag-strewn beauty spots and back alleys alike.

But the criticisms are twofold. First, some research suggests that the bags don't degrade as well as claimed. And second, priming plastic bags for destruction is itself an ecological crime.

So, do they really biodegrade away to nothing? Symphony, which supplies the Co-op and Tesco, says its bags are "able to degrade completely within about three years, compared to standard bags which take 100 years or longer". Tesco reckons they all decompose within 18 months "without leaving anything that could harm the environment".

But whether it actually happens seems to depend a lot on where the "biodegradable" plastic ends up. If it gets buried in a landfill it probably won't degrade at all because there is no light or oxygen. But what about elsewhere?

Studies of one brand in the US, commissioned by the Biodegradable Products Institute, found that breakdown is very dependent on temperature and humidity. It goes slow in cold weather. And high humidity virtually stops the process, making long, wet winters sound like bad news.

You might think a compost heap full of biodegrading bugs would be ideal. But a recent Swedish study found that polyethylene containing manganese additive stops breaking down when put in compost, probably due to the influence of ammonia or other gases generated by microorganisms in the compost.

And, while most manufacturers say that to put only tiny amounts of metals into the plastic, the US study found that one brand contained "very high levels of lead and cobalt", raising questions about the toxicity of the leftovers. Neither of these studies relates specifically to Symphony's products. But they raise questions.

The European Plastics Recyclers Association last week argued that biodegradable bags are not the right environmental option anyway. Plastic bags take a lot of energy and oil to make so why waste them by creating bags that self-destruct? "It is an economic and environmental nonsense to destroy this value," the recyclers' trade association concluded.

Of course, we consumers can reuse or recycle biodegradable bags as easily as any other kind. Symphony and other manufacturers stress making bags biodegradable is just an insurance policy for those that don't get recycled or reused. But surely we are less likely to bother if we are told the bags are eco-bags that biodegrade.

This European backlash against oxo-biodegradable plastics follows similar rumblings in the US. In March, the New York Times announced it would not be wrapping its paper in bags made of the stuff because claims that the plastic was "100% biodegradable" did not stand up. This followed a ruling last December by an advertising industry watchdog, part of the US Council of Better Business Bureaus, that makers should stop calling the bags "eco-friendly".

(In marked contrast, the UK Periodical Publishers Association two years ago recommended that all its members use oxo-biodegradable film to wrap their magazines)

Industry websites, including Symphony's, do proudly proclaim one green endorsement – that the organic trade body the Soil Association buys their bags. But Clio Turton at the Soil Association told me: "We've had problems with people making these claims. We have asked for them to be removed. It's very frustrating."

Plastic bags are not the biggest environmental issue on the planet, as George Monbiot explained in a blog here recently.

But most of us probably make "bag choices" several times a day. Brits get through 8bn plastic bags a year. For that reason, they are one of the choices that tend to show if we care about the environment or not. And we should be clear. Re-using bags is best. Recycling is second best. Throwing them away in the hope that a magic formula will guarantee their rapid disappearance is laziness, not environmental care. And anybody who tries to persuade us otherwise is guilty of Greenwash.

• This article was amended on Friday 19 June 2009. We should have made clear that the Soil Association no longer sells the biodegradable plastic bags referred to in this article. This has been corrected.

SM shifts to biodegradable bags

by Prix D Banzon

Davao City (3 May) -- Many are into saving mother Earth and SM City Davao is one of the many advocates of protecting the environment.

Two of its major anchors the SM Department Store and SM Supermarket had shifted into using biodegradable bags and the green bag respectively.

Using biodegradable bags, SM Department Store advocates the care for Mother Nature. Tagged as Oxo-Biodegradable Plastics or OBPs these are conventional plastics as polyethylene, polypropylene and polystyrene added with a proprietary mixture that accelerates the breakdown of the chemical structure of the plastics.

In a press statement, it said that these plastics are the main ones used in a variety of disposable packaging applications. The resultant breakdown products are then amenable to conversion by micro-organisms, for which these products are an energy source or food, or turned into carbon dioxide and water, thereby returning otherwise intractable plastics to the ecosystem.

Unlike other polyilefin products such as grocery and garbage bags, food wraps and liners for diapers which after use are discarded. The OBPs degrades into a form that is safely absorbed into the ecosystem in a timeframe that is similar to that of "natural" products such as stra, Kraft paper and leaves.

OBPs are widely used now, End users are adopting OBPs as an effective way to offer to the customers' environmentally responsible packaging in addressing concerns of government and the consuming public regarding the environmentally acceptable disposal of single use plastic products.

OBP's is not harmful to the people or the environment. Its active ingredient in oxo-biodegradable products, a transition metal salt (often of cobalt), is used at very low levels. Cobalt is a micro-nutrient essential for life. Studies have shown that composts made from oxo-biodegradable bags are not toxic to sensitive plant and animal organisms.

Meanwhile the green bag can last for approximately two years or more than 100 grocery trips. It is made of material that is recyclable, non-toxic, and allergy free.

The Biogradable Bags and the Greens Bag will be launched today, May 3 on SM's Trash and Cash Recycling Market Fair.

You can Save the World by using these bags.

Do Biodegradable Plastics Really Work?The answer, plus five more degrading questions.

— By Dave Gilson

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May/June 2009

Just how long does it take for conventional plastics to completely break down? 500 years? 1,000? It's a mystery. "No one has really measured how long it takes," says Ramani Narayan, a professor of chemical and biochemical engineering at Michigan State University. What is known is that conventional petroleum-based plastics never really go away, even when they break down into pieces too small to be seen with the naked eye. Some new plastics are designed to degrade (not to be confused with biodegrade—more on that in a sec) in a matter of weeks when exposed to the elements, but that doesn't mean they're truly gone.

But broken down plastics are better than litter, right? Wrong. In fact, plastics often create more environmental harm when broken down than when intact. This is most evident in the oceans, home to billions of pieces of disintegrating plastic and preproduction pellets called nurdles, which can work their way back up the food chain to humans.

What about biodegradable plastics? They're pretty neat: Microorganisms can convert biodegradable plastics into water, carbon dioxide, and biomass—with no nasty chemical leftovers. However, there is a lot of confusion surrounding these ecofriendlier plastics—some of it intentional. "This word 'biodegradable' has become very attractive to people trying to make quick bucks on it," explains Narayan, who helped develop biodegradable corn-based plastic. Some companies, he says, are making conventional plastic that degrades quickly and then throwing around claims about biodegradability that are unproven or just too good to be true.

Can biodegradable plastics break down in landfills? This claim, which now shows up on everything from water bottles to trash bags to Discover's "biodegradable PVC" credit cards, is "disingenuous at best," says Narayan. Usually, nothing biodegrades in a landfill. But if biodegradable plastics do break down in this oxygen-free environment, they'll emit methane, a greenhouse gas 23 times more potent than CO2.

How do I avoid fake biodegradable plastics? Currently, truly biodegradable plastics are mostly used for eating utensils, food containers, and compostable bags. To make sure you're getting the real deal, look for products with the Biodegradable Products Institute logo, which means they've been certified to comply with strict scientific standards.

So what's the best way to get rid of biodegradable plastic? "The public thinks that biodegradability means 'If I throw it away, it will completely go away,'" says Narayan. "They don't even know what 'going away' means." Real biodegradable plastic should be sent to a commercial composting facility, where it will spend its final days being eaten by microbes. But here's the catch: In 2007, only 42 communities nationwide offered compost collection. (Seventeen were in California.) And though some biodegradable plastics can be recycled, no curbside recycling program will take them. So before you buy biodegradable plastics, make sure you can help them "go away" the right way.

Oxo Biodegradable

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Oxo Biodegradable (OBD) plastic is polyolefin plastic to which has been added very small (catalytic) amounts of metal salts. These catalyze the natural degradation process to speed it up so that the OBD plastic will degrade when subject to environmental conditions to produce water, carbon dioxide and biomass. The process is shortened from hundreds of years to years and or months for degradation and thereafter biodegradation depends on the micro-organisms in the environment.

[edit] Degradation

Degradation is a process that takes place in all materials. The speed depends on the environment. Conventional polyethylene (PE) and polypropylene (PP) plastics will typically take hundreds of years to degrade. But oxo-biodegradable products utilize a prodegradant to speed up the molecular breakdown of the polyolefins and incorporate oxygen atoms into the resulting low molecular mass. This chemical change enables naturally-occurring microorganisms to consume the low molecular mass products as a food source, hence biodegradation.

[edit] Oxybiodegradation or Oxo-biodegradation

The process of degradation in OBD plastic is an oxidative chain scission that is catalyzed by small amounts of metal salts leading to oxygenated (hydroxylated and carboxylated) shorter chain molecules that are available for biomineralization by microorganisms, typically bacteria and fungi. OBD plastic if accidentally discarded in the environment, will degrade to oxygenated low molecular weight (typically MW 5-10.000 amu) within 2–18 months depending on the material (resin, thickness, anti-oxidants, etc.) and the temperature and other factors in the environment. There is little proof however to back up the common assumption that OBD plastics will degrade in a landfill environment due to insufficient oxygen present below a depth of approximately 15cm. A PE plastic bag for example 30 µm thick with 2% prodegradant additive degrades within 3 months if left exposed in an open air environment in Thailand and a 150 µm thick PP container or sheet will degrade within 3–6 months. The low molecular weight oxygenated molecules are then biomineralized ("eaten") by microorganisms in the same way that other organic matter is used by them to generate energy and build biomass.

OBD plastic is degradable and biodegradable, and can be recycled with normal plastic [1] but it is not as yet marketed as compostable. This is because the oxidation process takes longer than the 180 day period required by ASTM D6400 and similar standards for compostable plastics such as EN13432 and ISO 17088. This short time is necessary for compostable plastics because industrial composting has a short timescale, and is not the same as biodegradation in the environment. However, a material which completely converts itself into CO2 gas within 180 days (which is not the case for OBD) is not useful even in compost, and serves only to add to climate-change. A leaf is generally considered to be biodegradable but it will not pass the composting standard due to the 180 day limit in ASTM D6400.

Oxo-biodegradable products do not degrade so rapidly because they are stabilized to control the service-life of the product. They will nevertheless degrade more quickly than nature's wastes such as twigs and straw (c10 years) and much more quickly than ordinary plastic (many decades).

There is a Standard Guide (ASTM D6954) available which specifies procedures to test the degradability of oxo-biodegradable plastics however as this is only Standard guide as apposed to a Standard Specification it does not provide pass / fail criteria and therefore is of limited use in deciding whether a plastic should be marketed as "biodegradable". ASTM D6400 is a Standard Specification, but is appropriate only for compostable plastics. There is no need to refer to a Standard Specification unless a specific disposal route (e.g.: composting), is envisaged.

Why do we need oxo-biodegradable plastic?

Because thousands of tons of plastic waste are entering the world's environment every day, and will remain there for hundreds of years, unless collected for incineration.

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How does it work?

A very small amount of pro-degradant additive is put into the manufacturing process. This breaks the molecular chains in the polymer, and at the end of its useful life the product falls apart. The plastic does not just fragment, but will be consumed by bacteria and fungi after the additive has reduced the molecular weight to a level which permits micro-organisms access to the carbon and hydrogen.

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Does it really biodegrade, or does it just fragment?

When the material has reached the fragmentation stage it is no longer a plastic, and is "biodegradable" in the same way as nature's wastes such as straw and twigs. The process continues until the material has biodegraded to nothing more than CO2, water, and humus, and it does not leave fragments of petro-polymers in the soil.

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What does it cost?

Very little, because the additive represents less than 3% of the product, and because the products can be made with the same machines and workforce as ordinary plastic.

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Won't it put existing factories out of business, with loss of jobs?

No, because customers can still use the factories which supply them with ordinary plastic products.

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What types of biodegradable plastics exist?

The two main types are oxo-biodegradable and hydro-biodegradable. In both cases degradation begins with a chemical process (oxidation or hydrolysis), followed by a biological process. Both types emit CO2 as they degrade, but hydro-biodegradables (usually starch-based) can also emit methane. Both types are compostable, but only oxo-biodegradable can be economically recycled.

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What are the differences between oxo-biodegradable and hydro-biodegradable plastic?

See http://www.biodeg.org/position-papers/comparison/?domain=biodeg.org

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Surely education is the way to solve the litter problem?

Hopefully education will reduce the litter problem over several generations, but there is a lot of litter today and there will always be some litter. Action needs to be taken today to switch to oxo-biodegradable before millions more tons of plastic waste accumulate in the environment.

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Isn't it better to recycle than to let it biodegrade?

Yes, and one of the benefits of oxo-biodegradable plastic is that it can be recycled as part of a normal plastic waste stream (see http://www.biodeg.org/position-papers/recycling/?domain=biodeg.org) However, if the plastic is not collected it cannot be recycled, so it needs to biodegrade instead of accumulating in the environment.

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What about energy recovery?

In some countries incineration is popular, and modern equipment is in place. Oxo-biodegradable plastic can be incinerated with energy recovery in the same way as conventional plastic, and has a higher calorific value than the hydro-biodegradable alternative.

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Can it be composted?

Oxo-biodegradable plastic does not degrade quickly in low temperature "windrow" composting, but it is suitable for "in-vessel" composting at the higher temperatures required by the new EU animal by-products regulations. Indeed it is likely that windrow composting will soon have to be phased out.

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What happens to it in a landfill?

Oxo-biodegradable plastics fragment and partially biodegrade to CO2 and water in the parts of the landfill where oxygen is present, but the residues are completely inert deeper in the landfill in the absence of oxygen. They do not emit any significant amounts of methane.

By contrast, hydro-biodegradable (starch-based) plastics will degrade and emit CO2 in a landfill if there is enough microbial activity. However, in the depths of a landfill, in the absence of air, hydro-biodegradable plastics generate copious quantities of methane, which is a powerful greenhouse gas.

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Does it contain "heavy metals"?

No. It contains transition metal ions of Cobalt or Iron or Manganese, which are trace elements required in the human diet. They should not be confused with toxic heavy metals such as Lead, Mercury, Cadmium and Chromium, which are never used in oxo-biodegradable plastics.

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Isn't it made from oil?

Yes. Oxo-biodegradable plastics are currently made from a by-product of oil or natural gas. These are of course finite resources, but the by-product arises because the world needs fuels, and would arise whether or not the by-product were used to make plastic goods.

Until other fuels and lubricants have been developed for engines, it makes good environmental sense to use the by-product, instead of wasting it by "flare-off" at the refinery and using scarce agricultural resources to make plastics. In fact plastics could reduce the amount of oil and gas imported because after their useful life they can be incinerated to release the stored energy, which can be used to generate electricity or to heat buildings.

Recently, interest has been shown in manufacturing sugar-derived polyethylenes. These, like oil-derived PE, are not biodegradable, but they can be made oxo-biodegradable in the same way as the latter, by the addition of a pro-degradant additive.

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But aren't the hydro-biodegradable plastics renewable?

No. because the process of making them from crops is itself a significant user of fossil-fuel energy and a producer therefore of greenhouse gases. Fossil fuels are burned in the machines used to clear and cultivate the land, and in the manufacture and transport of fertilisers and pesticides and in transporting the crop itself. Energy is also used by the autoclaves used to ferment and polymerise material synthesised from biochemically produced intermediates (e.g. polylactic acid from carbohydrates etc). When the material biodegrades it emits CO2 and methane, so the total fossil fuels used and greenhouse gases emitted are more than for conventional or oxo-biodegradable plastic.

Hydro-biodegradables are sometimes described as made from "non-food" crops, but are in fact usually made from food crops, and drive up the price of human and animal food.

In June 2009 Germany's Institute for Energy and Environmental Research concluded that oil-based plastics, especially if recycled, have a better Life-cycle Analysis than compostable plastics.

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Does it leave any harmful residues?

No. Oxo-biodegradable plastic passes all the usual ecotoxicity tests, including seed germination, plant growth and organism survival (daphnia, earthworms) tests carried out in accordance with international standards.

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Deliberately and totally lost?

The argument that oxo-biodegradable plastics are undesirable because their components are designed to be deliberately and totally lost is a fallacy, because if people want to incinerate with heat recovery, or mechanically recycle them, or compost them in-vessel, or re-use them, then that's OK, and they cost very little if anything more than conventional products. The key point is what happens to the plastic which is not collected, and gets into the environment as litter?

In any event, oxo-biodegradable plastics are not "deliberately and totally lost" even if they degrade in the environment, because biodegradation on land is a source of plant nutrients, just as is straw, grass, leaves etc.

By contrast, hydro-biodegradable plastics are "deliberately and totally lost" because the applicable international standards require them to convert to CO2 gas within 180 days.

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More careless disposal?

Degradable plastic bags have been supplied by supermarkets for more than four years, but there is no evidence that people dispose more carelessly of them (whether oxo or hydro biodegradable) and they have not been encouraged to do so.

But suppose for the sake of argument that 10% more were discarded. If 1,000 conventional and 1,100 oxo-biodegradable bags were left uncollected in the environment, 1,000 conventional bags would remain in the rivers, streets and fields for decades, but none of the oxo-biodegradable bags would be left at the end of the short life programmed into them at manufacture.

There will always be people who will deliberately or accidentally discard their plastic waste. What will happen to all the plastic waste that will not be recycled or will not be incinerated, and instead will litter the countryside - would it not be better if the discarded plastic were all oxo-biodegradable?

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Is it safe for food-contact?

Yes. Oxo-biodegradable plastic has been certified by RAPRA Technology Analytical Laboratories as safe for long-term contact with any food type at temperatures up to 40°C. RAPRA is accredited by the United Kingdom accreditation authorities as meeting the requirements of International Standards Organisation norm no. 17025. It is also certified as compliant with FDA requirements in the US.

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Can it be marketed as Biodegradable or Compostable?

On 8th April 2010 the Advertising Standards Authority of South Africa ruled that bread bags made with oxo-biodegradable plastic can be advertised as Biodegradable.

The current EU Standard for composting (EN13432) is not appropriate for testing oxo-biodegradable plastic. However the EU Packaging Waste Directive does NOT require that when a packaging product is marketed as "degradable" or "compostable" conformity with the Directive must be assessed by reference to EN13432. The Directive provides that conformity with its essential requirements may be presumed if EN 13432 is complied with, but it does not exclude proof of conformity by other evidence, such as a report from a reputable body. Indeed Annex Z of EN13432 itself says that it provides only one means of conforming with the essential requirements.

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Isn't it better to use paper bags?

No. The process of making paper bags causes 70% more atmospheric pollution than plastic bags. Paper bags use 300% more energy to produce, and the process uses huge amounts of water and creates very unpleasant organic waste. When they degrade they emit methane and carbon dioxide.

A stack of 1000 new plastic carrier bags would be around 2 inches high, but a stack of 1000 new paper grocery bags could be around 2 feet high. It would take at least seven times the number of trucks to deliver the same number of bags, creating seven times more transport pollution and road congestion.

Also, because paper bags are not as strong as plastic, people may use two or three bags inside each other. Paper bags cannot normally be re-used, and will disintegrate if wet.

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Isn't it better to use durable re-usable bags?

No. Long-term re-usable shopping bags are not the answer. They are much thicker and more expensive, and a large number of them would be required for the weekly shopping of an average family. They are not hygienic unless cleaned after each use. Whilst sometimes called "Bags for Life" they have a limited life, depending on the treatment they receive, and become a very durable problem when discarded.

Shoppers do not always go to the shop from home, where the re-usable bags would normally be kept, and consumers are unlikely to have a re-usable bag with them when buying on impulse items such as clothing, groceries, CDs, magazines, stationery etc.

However, for those who believe in long-term re-usable bags, they can be made from extended-life oxo-biodegradable plastic and will last for 3-5 years.

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How long does it take to completely degrade?

An important advantage of oxo-biodegradable plastic is that it can be programmed to degrade in whatever timescale is required. The average useful life of a carrier bag is about 18 months, but shorter or longer times are possible. During that time bags are often re-used for shopping or for use as bin-liners etc. Heat and light will accelerate the process, but they are not essential.

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