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

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 Cultural Hazards Smoking Poor Diet Poverty Unsafe sex

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

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

“The dose makes the poison” 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 h when exposed to light DDT (kills insects) breaks down in 2 to 15 years

Toxicology Chemical interactions - two (or more) 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 + =

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

Case Study – DDT Dichlorodiphenyltrichloroethane Used as an insecticide beginning in the 1940s, primarily in tropical areas of the world with malaria and typhus Highly effective at killing insects WHO estimates that its use has saved 25 million lives

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 Should DDT be banned everywhere in the world? Should there be exemptions? Should a product, like DDT, be allowed if it saves human lives while harming wildlife?

STEPS TO MEASURE RISK 1. 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 RISK 2. 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 RISK 3. 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.

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.

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.

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 RISK Toxicity Ratings

Risk Assessment vs. Risk Management Risk Assessment “What is the hazard?” Risk Management “How can the risk be minimized?”