what are you most scared of? fireworks discharge lightning gunshot earthquake car accident
TRANSCRIPT
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