Do Now • Thinking outside the box. With only using four lines

and not picking up your pen or pencil. Connect all the dots below:

* * *

* * *

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Answer• Thinking outside the box. With only using four lines and not picking up

your pen or pencil. Connect all the dots below:

* * *

* * *

* * *

• Due Friday –Vocab 1-95• 91. Photovoltaics • 92. Law of Averages• 93. Habitat versus Niche• 94. Directional Selection • 95. Disruptive Selection• Test Friday & Saturday on Chapters 13 & 14. • Read pages 383 starting at Airborne

substances…to 388 stop at Dose – response…

Homework

Lead poisoning

• Lead poisoning = caused by lead, a heavy metal– Damages the brain, liver, kidney, and stomach– Causes learning problems, behavior abnormalities,

and death• Exposure is from drinking water that flows

through lead pipes or from lead paint• Education led to declines in poisoning, but China

still used it in toy paint until recently

Remember the video about the computers be recycling?

• Polybrominated diphenyl ethers (PBDEs) = has fire-retardant properties– Used in computers, televisions, plastics, and furniture– Persist and accumulate in living tissue– Mimic hormones and affect thyroid hormones– Also affect brain and nervous system development and

may cause cancer• Concentrations are rising in breast milk– Now banned in Europe, concentrations have decreased– The U.S. has not addressed the issue

New Material• Despite our technology,

disease kills most of us• Disease has a genetic

and environmental basis– Cancer, heart

disease, respiratory disorders

– Poverty and poor hygiene foster illnesses

• Infectious diseases kill 15 million people/year– Half of all deaths in developing countries

• Public health decreases some infectious diseases such as (AIDS) and is spreading

New Material

• Our mobility spreads diseases - Remember Spanish Influenza during WW I. - West Nile Virus spread from Africa to all lower

48 U.S. states in 5 years- And early on AIDS

• New diseases are emerging such as - H5N1 avian flu, H1N1 (Swine Flu)

New Material

• Toxicology = the study of the effects of poisonous substances on humans and other organisms

• Toxicity = the degree of harm a toxicant can inflict• Toxicant = any toxic substance (poison)– “The dose makes the poison” = toxicity depends on

the combined effect of the chemical and its quantity• Environmental toxicology = deals with toxic

substances that come from or are discharged into the environment– Studies health effects on humans, other animals, and

ecosystems

Toxicology studies poisonous substances

• What is the most dangerous place in a home for poisonous substances?

• Under the kitchen sink?

Toxicology studies poisonous substances

• 80% of U.S. streams contain 82 contaminants– Antibiotics, detergents, drugs, steroids, solvents, etc.

• 92% of all aquifers contain 42 volatile organic compounds (from gasoline, paints, plastics, etc.)– Less than 2% violate federal health standards for

drinking water

–DDT - Rachel Carson’s Silent Spring (1962) showed DDT’s risks to wildlife, and ecosystems and possibly people

Chemicals are in the air, water, and soil

Toxicants

• Carcinogens = cause cancer– Hard to identify because of the long time between

exposure and onset of cancer• Mutagens = cause DNA mutations– Can cause cancer

• Teratogens = cause birth defects in embryos• Neurotoxins = assault the nervous system• Allergens = overactivate the immune system • Endocrine disruptors = affect the endocrine

(hormone) system

Endocrine disruptors• Hormones stimulate

growth, development, sexual maturity

• Synthetic chemicals – Can Block hormones

and / or mimic hormones

Bisphenol A

• Bisphenol A binds to estrogen receptors

• Phthalates in plastics disrupt hormones– Found in toys,

perfumes, makeup– Can cause Birth

defects, cancer, reproductive effects

Airborne substances

• Chemicals can travel by air– Their effects can occur

far from the site of use• Pesticide drift = airborne

transport of pesticides• Synthetic chemicals are

found globally– In arctic polar bears,

Antarctic penguins, and people in Greenland

Some toxicants persist

• Toxins can degrade quickly and become harmless or they may remain unaltered and persist for decades– Rates of degradation depend on the substance,

temperature, moisture, and sun exposure• Breakdown products = simpler products that

toxicants degrade into may be more or less harmful than the original substance– DDT degrades into DDE, which is also highly persistent

and toxic.

New Material• Toxicants in the body can

be excreted, degraded, or stored fat-soluble toxicants are stored in fatty tissues

• Bioaccumulation = toxicants build up in animal tissues

• Biomagnification = concentrations of toxicants become magnified– Near extinction of peregrine

falcons and bald eagles

Not all toxicants are synthetic• Toxic chemicals also exist naturally and in our

food– Don’t assume natural chemicals are all healthy and

synthetic ones are all harmful. For example mushrooms

• Environmentalists say synthetic toxins:– Are harder to metabolize and excrete– Persist and accumulate– Enter people in ways other than in food

Human studies

• Case history approach = studies individual patients– Autopsies tell us about lethal doses– Don’t tell about rare, new, or low-concentration toxins– Don’t tell about probability and risk

• Epidemiological studies = large-scale comparisons between exposed and unexposed groups– Studies can last for years– Yield accurate predictions about risk–Measure an association between a health hazard and

an effect – but not necessarily the cause of the effect