What are you most scared of?

• Shark attack• Motorcycling• Snakebite• Smoking• Driving• Airplane crash

What are you most scared of?

• Shark attack – 1 in 281 million• Motorcycling – 1 in 50 participants• Snakebite – 1 in 56 million• Smoking – 1 in 300 participants by

age 65• Driving – 1 in 6,700• Airplane crash – 1 in 9 million

Chapter 10: Risk, Toxicology, & Human

Health

Topics

• What is risk?• Quantitative measurements - “It’s

a numbers game.”• Qualitative Risk - “It’ll never

happen to me.”• Risk Management - “What are we

going to do about it?”

What is risk?• "Jack Gibbons, President Clinton's

science adviser, was fond of saying that risk assessment is as old as cave dwellers trying to assess what the probability of an adverse outcome might be if they confronted a wooly mammoth, and at the same time the benefits of doing so."

What is Risk?Risk –

possibility of suffering harm from a hazard

Impacts of Risks on Humans Mortality (death) Morbidity (illness) Loss of quality of life Loss of work days Property damage

Examples of Cultural Hazards Smoking Poor Diet Poverty Unsafe sex Drinking Driving

Examples of Chemical Hazards

Air Water Soil Food

Examples of Physical Hazards Fires Earthquakes Volcanic eruptions Floods Tornadoes Hurricanes

Examples of Biological Hazards

Pathogens Pollen Allergens Animals

Which type of hazard do these fit into?

Quantitative Measures of Risk

Measured in Probabilities - a mathematical statement about the likelihood of harm

Can be expressed in three ways: 1:100 1/100 “One in one hundred”

What was Ben Stiller’s job in the movie?

Quantitative Measures of Risk Ex: 1:6,210 - risk of dying from alcohol

(1 person in 6,210 people will die of alcohol related illness)

The bigger the bottom number (denominator) the less the chance Ex: chance of winning Power Ball

lottery: about 1 in 80,000,000 Ex: chance of laughing at with Mr.

Colosi today: about 1 in 3

Quantitative Measures of RiskIt’s all in the numbers

Statements of risk are statements about the future.

The purpose of measuring risk is to guide behavior.

We monitor our environment for signs of safety or danger, and then modify our behavior in response to our environment.

We constantly do a cost-benefit analysis. “What will I gain compared to what I might lose?”

Quantitative Measures of RiskIt’s all in the numbers

STEPS TO MEASURE RISK

1. Problem Identification

2. Exposure assessment

3. Toxicity Assessment

4. Risk Characterization

STEPS TO MEASURE RISK1. Problem Identification

Scientific or public concerns about harm from a

particular substance often initiate the problem

identification process.

Evidence is gathered by:

Animal studies

Test tube studies

Comparison studies – the properties of the

substance are compared with substances

known to be harmful.

STEPS TO MEASURE RISK2. Exposure Assessment Estimates how much of a substance a

population inhales, ingests, or absorbs through the skin (aka the “dose”)

Some of the factors we must consider are: How long people have been exposed Whether the exposure was continuous or

intermittent How they were exposed – inhalation,

ingestion, or absorption through the skin

STEPS TO MEASURE RISK2. Exposure Assessment - Dose & Response

The amount of damage (response) is related to the dose you get

Response is related to age, gender, and genetic makeup Also immune

system (detox)

STEPS TO MEASURE RISK2. Exposure Assessment

Solubility - what can the chemical dissolve in? Water is better since it can be diluted Fats aren’t good since chemicals can gather in

body fat of animals. Persistence - how long does a chemical stay in

the environment? Roundup (kills plants) breaks down in 24 h

when exposed to light DDT (kills insects) breaks down in 2 to 15

years Chemical interactions - two factors together

can have a greater effect than each by themselves Being exposed to asbestos (insulation) and

smoking give you a 400 times greater chance of lung cancer

STEPS TO MEASURE RISK2. Exposure Assessment

Bioaccumulation chemicals stored in organs (fat)

of animals Biomagnification

chemicals are passed to each member of the food chain• Large amounts in animals at

top of chain Chemical Interactions

Antagonistic interactions –can reduce harmful effects of a toxin ex. some vitamins (A and E) may reduce the body’s response to some cancer causing chemicals

Synergistic interactions – multiplies harmful effects; ex. workers who are exposed to tiny fibers of asbestos have an increased risk of lung cancer and those who smoke have an even greater chance

Response: the type of damage (acute vs. chronic)

STEPS TO MEASURE RISK3. Toxicity Assessment Toxicity assessments estimate how

much of a substance does what kind of harm

The toxicity assessment step looks at how much of a substance causes what kind of harm to humans.

Toxicity to humans is not usually measured directly by intentionally exposing people, for obvious ethical reasons.

STEPS TO MEASURE RISK3. Toxicity Assessment

An interesting animal study concerning the artificial sweetener saccharin

Animal studies indicated that saccharine caused bladder cancer in animals. In 1977, the FDA proposed a ban on its use.

Studies later reveled that the doses given to animals were the equivalent of a human drinking 100 cans of soda a day. Human tests never linked saccharine to human cancer because the way that saccharine gave cancer to rats does not happen in humans.

Saccharine was taken off the FDA’s possible cancer list in 2000, after 25 years of needless worry.

Worry is still around today.

3. Toxicity Assessment - Poisons

Poisons – materials that kill at a very small dose (50 milligrams or less per kilogram of weight)

The LD50 (lethal dose) is the amount that kills 50% of a test population in a given time.

3. Toxicity Assessment -Poisons

The LD50 of this chemical is 7.Look along the blue curve. The dose that kills 50% is the LD50.

STEPS TO MEASURE RISK3. Toxicity Ratings

Toxicity Rating LD50

Average Lethal Dose Examples

super toxic < 0.01 less than 1 drop nerve gases, botulism, mushroom toxins, dioxin

extremely toxic

< 5 less than 7 drops potassium cyanide, heroin, atropine, parathion, nicotine

very toxic 5–50 7 drop to 1 teaspoon

mercury salts, morphine, codeine

toxic 50–500 1 teaspoon to 1 ounce

lead salts, DDT, sodium hydroxide, fluoride, sulfuric acid, caffeine, carbon tetrachloride

moderately toxic

500–5,000 1 ounce to 1 pint methyl alcohol, ether, pehobarbital, amphetamines, kerosine, aspirin

slightly toxic 5,000–15,000 1 pint to 1 quart ethyl alcohol, lysol, soapsessentially nontoxic

> 15,000 more than 1 quart water, glycerin, table sugar

Qualitative RiskIt’ll never happen to me

The public generally interprets the following types of risks as serious:

1. Involuntary risk 2. Unfamiliar Risks3. Other factors

Oh no! A risk!

Qualitative RiskIt’ll never happen to me Involuntary risk — for example, people

usually consider the risk of exposure to toxic substances more serious than the risk of driving.

>

Qualitative RiskIt’ll never happen to me

Unfamiliar, unnatural, or new situations that could have catastrophic potential. Risks connected to recent visible events

We determining the probability of an event based on information the mind can imagine or retrieve.

For example, people may be concerned about a catastrophe if they've seen a recent occurrence on evening news broadcasts, even if odds are slim such an occurrence will befall them.

Unfamiliar Situations in the News

Unfamiliar Situations in the News

Unfamiliar Situations in the News

LEAD IN LIPSTICK??? LEAD is toxic - mainly

because it preferentially replaces other metals (e.g., zinc, calcium and iron) in biochemical rxns Lead interferes with the proteins that cause certain genes to turn on and off by displacing other metals in the molecules. This changes the shape of the protein molecule such that it can't perform its function.

Paracelsus' idea that the dose makes the poison doesn't really apply with lead. Many substances are non-toxic/essential in trace amounts, yet poisonous in quantity You need iron to transport oxygen in your red blood cells, yet too much iron can kill you. Lead is simply poisonous. The main concern is lead exposure with small children, because lead can cause developmental problemsThere is no minimum safe exposure limit, because lead accumulates in the body. There are government regulations regarding 'acceptable' limits for products and pollution, because lead is useful and necessary, but the reality is, any lead is too much lead

LEAD

Qualitative RiskIt’ll never happen to me Other factors - social injustice,

distrust of government officials, and outrage. Researchers need to consider public

perceptions to determine if they are mental shortcut errors, or if the risk is legitimate and ought to be believed.

Unfair Distribution of Risk

Unfair Distribution of Risk

Risk Assessment vs. Management

Risk Management - “What are we going to do about it?”

Risk assessment is distinct from risk management. Risk assessment is a scientific

process of investigating phenomena to estimate the level of risk.

Risk management attempts to reduce the risk that has been discovered through risk assessment.

Risk Management - “What are we going to do about it?”

Risk managers use the results of risk assessments, plus economic, social, and legal considerations to make regulatory and policy decisions.

While economic, social, and legal considerations have a legitimate place in risk management, they have no place in the scientific process of risk assessment.

Risk Management What information do you need to

know about a risk in order to manage it? How reliable is the risk assessment? How much of the risk is acceptable? How much will it cost to reduce the risk

to an acceptable level? How will the risk management plan be

monitored and enforced?

Do You Agree or Disagree? We shouldn’t get so worked up

about exposure to toxic chemicals because almost any chemical can cause harm at a large enough dose.

Do You Agree or Disagree? Pollution levels should be set to

protect the most sensitive people in a population.

I do . . . . agree.

Do You Agree or Disagree? Cigarettes should be made illegal.

Risk Assessment vs. Risk Management

Risk Assessment “What is the hazard?”

Risk Management “How can the risk be minimized?”

Section 3: Chemical Hazards

What are toxic and hazardous chemicals? What are some possible impacts from

chemical hazards? Are hormonally active agents a human

health threat? Why do scientists no so little about the

impacts of chemicals on human health? Is pollution prevention the answer?

What are toxic and hazardous chemicals?

Toxic Chemical: a chemical through that can cause temporary or permanent harm or death.

Hazardous Chemical: can harm humans because it is flammable or explosive.

Types of Toxic Agents

Mutagen: causes changes to ones DNA.

Teratogens: chemicals that cause birth defects to fetus or embryo. (alcohol)

Carcinogens: cause cancer (growth of cancerous tumors)

Impacts of Chemicals on Humans

Chemicals may also impact: Immune system (arsenic,

dioxin) Nervous System (neurotoxins,

brain, spinal cord, etc.) Endocrine System (levels of

hormones)

Hormonally Active Agents

Exposure to low level certain synthetic chemicals may disrupt a bodies hormone levels

Endocrine disrupters or hormonally active agentsSo called, gender benders

Establishing Guilt Is Difficult

Under current laws, most chemicals are considered innocent until proven guilty.

“Toxicologist know a great deal about a few chemicals, a little about many, and nothing about most.”

Establishing Guilt Is Difficult

U.S. National Academy of Sciences estimates that only 10% of the 80,000 chemicals in commercial use have been tested for toxicity.

Why? Not required (considered innocent) Lack of funds, personnel, facilities Expensive Difficult to test interactions

Pollution Prevention Model

Where do we go from here?

We do not know much about all of the chemicals inside us, around us

Eliminating them mean other problems

Some say Pollution Prevention,

Pollution Prevention Model

Precautionary Principle: where there is plausible, but incomplete scientific evidence of significant harm we need to take action to reduce the risk.

“Better Safe Than Sorry”

Pollution Prevention ModelFirst: new chemical

technologies would be considered harmful until studies say otherwise.

Second: existing chemicals that appear to be harmful would be removed from use.

Transmittable and Nontransmittable Diseases

Nontransmissible: caused by something other than a living organism and does not spread from person to person. (cancer, diabetes, etc.)

Transmissible: caused by living organisms and can spread from person to person. (bacteria, virus, parasite)

Transmittable and Nontransmittable Diseases

According to WHO: 30% of deaths are nontransmissible and 26% transmissible IDs and 12% nontransmissibe cancers.

Transmittable and Nontransmittable Diseases

Good News: Since 1950, ID death rates fallen dramatically.

Bad News: Bacteria resistance growing and insects becoming immune to pesticides.

Biological Hazards: DiseasesBiological Hazards: Diseases

Nontransmissible diseaseNontransmissible diseaseTransmissible diseaseTransmissible diseasePathogensPathogensVectorsVectorsTuberculosisTuberculosisHIV/AIDSHIV/AIDSMalariaMalaria

Fig. 19-13 p. 425

TB Kills 1.7 million people per year.

Reducing Infectious Diseases

Fig. 19-15 p. 426

Bioterrorism

Possible targets: air, water, and food

Inexpensive

Fairly easy to produce biological agents

Recombinant DNA techniques

Refer to Fig. 19-16 p. 427