Presentation on theme: "What are you most scared of? Shark attack Motorcycling Snakebite Smoking Driving Airplane crash."— Presentation transcript:
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.""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 Smoking Poor Diet Poor Diet Poverty Poverty Unsafe sex Unsafe sex Drinking Drinking Driving Driving
Examples of Chemical Hazards Air Air Water Water Soil Soil Food Food
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 Risk It’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 Risk It’s all in the numbers STEPS TO MEASURE RISK Problem Identification Exposure assessment Toxicity Assessment Risk Characterization
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 dose 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 2. 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 RISK 2. 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 RISK 2. 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 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.
STEPS TO MEASURE RISK 3. 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) amount The LD 50 (lethal dose) is the amount that kills 50% of a test population in a given time.
3. Toxicity Assessment - Poisons The LD 50 of this chemical is 7. Look along the blue curve. The dose that kills 50% is the LD 50.
STEPS TO MEASURE RISK 3. Toxicity Ratings
Qualitative Risk It’ll never happen to me The public generally interprets the following types of risks as serious: 1. Involuntary risk 2. Unfamiliar Risks 3. Other factors Oh no! A risk!
Qualitative Risk It’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 Risk It’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
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 problems There 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 Risk It’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
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?”