What are you most scared of?

• Fireworks discharge

• Lightning

• Gunshot

• Earthquake

• Car accident

Your chance of dying from . . .

• Fireworks discharge – 1 in 386,766

• Lightning – 1 in 84, 079

• Gunshot – 1 in 6,309

• Earthquake – 1 in 148,756

• Car accident – 1 in 66

Statistics from National Safety Council

Chapter 10: Risk, Toxicology, & Human Health

What is risk?

Risk – possibility of suffering harm from a hazard

Impacts of risks on humans Mortality Morbidity Loss of quality of life Loss of work days Property damage

Examples of Examples of Cultural HazardsCultural Hazards

SmokingSmoking Poor DietPoor Diet PovertyPoverty Unsafe sexUnsafe sex

Examples of Examples of Chemical HazardsChemical Hazards

AirAir WaterWater SoilSoil FoodFood

Examples of Examples of Physical HazardsPhysical Hazards

FiresFires EarthquakesEarthquakes Volcanic eruptionsVolcanic eruptions FloodsFloods TornadoesTornadoes Hurricanes Hurricanes

Examples of Examples of Biological HazardsBiological Hazards

PathogensPathogens PollenPollen AllergensAllergens Animals Animals

Quantitative Measures of Risk Probabilities - a

mathematical statement about the likelihood of harm

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

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. Strogen

today: about 1 in 3

Toxicology Dose – the amount of a substance that a person has in their body

Can be:• Ingested• Inhaled• Injected • Absorbed

“The dose makes the poison”

Sensitivity to Toxins The amount of

damage (response) is related to the dose you get

Response is related to age, gender, and genetic makeup

Toxicology Solubility - what can the chemical dissolve in?

Water-soluble toxins Oil/Fat-soluble toxins

Which do you think is generally “better” for the health of an organism? Water is “better” since it can be diluted Fats aren’t good since chemicals can gather in body fat of animals

Toxicology

Persistence - how long a chemical stays in the environment Roundup (kills plants) breaks down in 24 hours

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

Toxicology

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

Interactions

Synergistic interactions: when two (or more) risk factors have a greater effect together than each by themselves Ex: being exposed to asbestos and smoking gives

you a 400 times greater chance of developing lung cancer than if you experienced only one of those risks

+ =

Interactions

Antagonistic interactions: an exposure of two (or more) chemicals results in a reduction in the effect compared to when taken individually Ex: mercury toxicity can be reduced by consuming the

chemical dimercaprol

+ =

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 caused 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.

Toxicity Assessment 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

Toxicity Assessment

•The LD50 of this chemical is 7

•The dose that kills 50% is the LD50

LD50

LD50 = 5.3

STEPS TO MEASURE RISKToxicity 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

Threshold

Effects of KCl on Daphnia

0%10%20%30%40%50%60%70%80%90%

100%

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7

Concentration (mg/L)

% M

ort

alit

y

Case Study – DDT Dichlorodiphenyltrichloro

ethane Used as an insecticide

beginning in the 1940s, primarily in tropical areas of the world with malaria and typhus

Highly effective at killing insects

USNAS estimates that DDT saved 500 million lives

• In 2010, malaria killed 655,000 people• There are currently 216 million people infected• Every minute, an African child dies of malaria

Case Study – DDT 1962, Rachel Carson wrote Silent Spring,

which described the negative effects of pesticides, like DDT: Cancer in humans Thinner egg shells, reproductive problems,

and death in birds Carson was concerned with the

widespread spraying of chemicals, especially since we didn’t fully understand its effects on the environment or humans

Case Study – DDT Silent Spring resulted in a public

outcry to ban DDT 1972, banned in the US 2004, banned worldwide (some

exemptions) Often cited as the beginning of the

“environmental movement”

DDT Discussion How much do you agree with the

following statement?

Despite its usefulness at preventing diseases like malaria (and saving millions of lives each year), DDT should be banned worldwide because of its negative environmental and health effects.

Chemical Risks Neurotoxins:

chemicals that disrupt the nervous system Carcinogens:

chemicals that cause cancer Teratogens:

chemicals that interfere with the normal development of embryos and fetuses

Allergens: chemicals that cause allergic reactions

Endocrine disruptors: chemicals that interfere with the normal functioning of

hormones

Risk Assessment vs. Risk Management

Risk Assessment “What is the hazard?”

Risk Management “How can the risk be minimized?”

Risk Analysis

Qualitative vs. Quantitative

• Qualitative risk assessment: judging the relative risk of various decisions (ex: low, medium, or high)

• Judgments based on perception, not on actual data

• Quantitative risk assessment: determining the probability of an event occurring using data (ex: 83% chance)

Probabilities of Death in U.S.

Risk Analysis

Risk =Probability of being exposed to a hazard

Probability of being harmed if exposedx

Risk Analysis

What is riskier: flying on a plane for 1,000 miles per year or eating 40 tablespoons of peanut butter per year? The probability of a plane crash is low, but the

probability of dying if the plane crashes is high The probability of eating peanut butter is high, but

the probability of developing cancer from the peanut butter is low

Both behaviors produce a risk of 1 in 1 million

Chemical Regulation