risk, toxicology, and human health. 1. what do you think is the single biggest threat to your life?...
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1. What do you think is the single biggest threat to your life?
2. What do you think is the single biggest threat to a teenager in a developing country?
3. What do you think is the single biggest threat to someone of my generation?
Warm Up 2/19/2015
ORDERING OF PERCEIVED RISK
Activity League of Women Voters
College Students Experts
Nuclear Power 1 1 20
Motor Vehicles 2 5 1
Handguns 3 2 4
Smoking 4 3 2
Motorcycles 5 6 6
Alcoholic Bev. 6 7 3
General Aviation 7 15 12
Police Work 8 8 17
Pesticides 9 4 8
Surgery 10 11 5
Firefighting 11 10 18
X-rays 22 17 7
RISK, PROBABILITY AND HAZARDSRisk: is the possibility of
suffering a harm from a hazard that can cause injury, disease, death, economic loss, or environmental damage.
Risk Assessment: the scientific process of estimating harm a particular hazard may cause.
Risk Management: deciding whether or not to reduce a risk and at what cost.
WHAT IS RISK? Risk is expressed in probabilities.
Example: “The lifetime risk of developing lung cancer is 1 in 250 from smoking a pack a day”
Plane crash: 1 in 10 million
Lightning: 1 in 1.4 million
House Fire: 1 in 200
HAZARDS: TYPES OF RISK
Cultural hazards: working conditions, diet, driving,unsafe sex, poverty, etc.
HAZARDS: TYPES OF RISK
Chemical hazards: harmful chemicals in the air, water, soil and food.
Example: DDT or PCBs
HAZARDS: TYPES OF RISK
Biological hazards: pathogens (bacteria, virus, parasites), pollen, animals, plants.
TOXICOLOGY: ASSESSING CHEMICAL HAZARDS
Toxicity: measure of
how harmful a
substance is in
causing injury,
illness, or death to
living organisms.
TOXICOLOGY: VARYING FACOTRS1) Dose: the amount of substance ingested, inhaled
or absorbed.
2) Age of individual
3) Immune System (detoxification)
4) Genetic Makeup
5) Length and frequency of exposure
FACTORS AFFECTING HARM CAUSED BY A SUBSTANCE
1)Solubility
• Water soluble toxins move through
environment easily• Fat soluble
can accumulate in body tissue and cells
FACTORS AFFECTING HARM CAUSED BY A SUBSTANCE2) Persistence - how long before it
breaks down Bioaccumulation – some
molecules are absorbed and stored in specific organs or tissues at higher than normal levels
FACTORS AFFECTING HARM CAUSED BY A SUBSTANCE
3) Biomagnification – some toxins are magnified as they pass through food chains and food webs. DDT PCBs (Polychlorinated
biphenyls)
FACTORS AFFECTING HARM CAUSED BY A SUBSTANCE
4) Chemical interactions For example: workers exposed to asbestos =20x more likely to get lung cancer.
If they smoke also=400x.
FACTORS AFFECTING HARM CAUSED BY A SUBSTANCE
Response: the type of damage resulting from exposure to a chemical or other agent
•Acute – immediate reaction• Chronic – permanent of long-lasting
PRINCIPLES OF TOXICOLOGYAny synthetic or natural chemical can be harmful if ingested in large enough quantity.
THE DOSE MAKES THE POISON
Critical questions: what is the lowest level that will cause harm?
PRINCIPLES OF TOXICOLOGY Trace amounts of chemicals in the environment may or may not be harmful.
Some say they are not, look at life expectancy over last several centuries.
Some say they are, look at cancer rates and say it is hard to know long-term impacts.
PARTNER WARM UP Partner A – What is toxicity? Name three factors that can effect toxicity?
Partner B – Some people argue that trace amounts of chemicals in the environment may or may not be harmful. Give evidence that supports either side of the argument.
FACTORS AFFECTING TOXICITY OF A CHEMICAL 1. Dose
2. Age
3. Immune System
4. Genetic Makeup
5. Exposure
6. Solubility
7. Persistence (bioaccumulation)
8. Biomagnification
9. Chemical Interactions
PRINCIPLES OF TOXICOLOGY Trace amounts of chemicals in the environment may or may not be harmful.
Some say they are not, look at life expectancy over last several centuries.
Some say they are, look at cancer rates and say it is hard to know long-term impacts.
PRINCIPLES OF TOXICOLOGYAny synthetic or natural chemical can be harmful if ingested in large enough quantity.
THE DOSE MAKES THE POISON
Critical questions: what is the lowest level that will cause harm?
POISONS
Median lethal dose (LD50): at this dosage the toxin kill 50% of animals(usually mice or rats)
POISONSThreshold – The dose below which no toxic effects are observed and/or above which the toxic effects are apparent
PRINCIPLES OF TOXICOLOGY
How do scientists determine toxicity:
1)Epidemiologic case studies
2)Animal Testing
3)Computer modeling
PRINCIPLES OF TOXICOLOGY
How good are the estimates of toxicology?
There are serious limitations to all these types of studies.
Therefore, most allowable limits are set well below estimated harmful levels.
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.
Ex: Radiation. Nitrous acid formed during digestion of nitrite preservatives.
Teratogens: chemicals that cause birth defects to fetus or embryo. (ex: alcohol, drugs)
TYPES OF TOXIC AGENTS
Carcinogens: cause cancer (growth of cancerous tumors)
Ex. Benzene (chemical solvent)
WARM UP 2/24/20141)Give an example of a:
- Biological hazard- Chemical hazard- Physical hazard - Cultural hazard
2)What is the difference between a mutagen, teratogen, and carcinogen
3)Explain what LD50 means.
POISONS
Median lethal dose (LD50): at this dosage the toxin kill 50% of animals(usually mice or rats)
IMPACTS OF CHEMICALS ON HUMANS
Chemicals may also impact: Immune system (arsenic, dioxin) Nervous System(neurotoxins, brain, spinal cord)
Endocrine System (levels of hormones)
IMPACTS OF CHEMICALS ON HUMANS
Arsenic – one of the most toxic elements on earth.- Found naturally
in deep rocks/ volcanos
- Produced to make glass and wood preservatives
HORMONALLY ACTIVE AGENTS
Exposure to low level certain synthetic chemicals may disrupt a bodies hormone levels
Endocrine disrupters or hormonally active agents
Ex: Bisphenol A (BPA)
ESTABLISHING GUILT IS DIFFICULTUnder 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.
ESTABLISHING GUILT IS DIFFICULT
Why are not all chemicals tested? Not required (considered innocent) Lack of funds, personnel, facilities Expensive Difficult to test interactions
POLLUTION PREVENTION MODELWhere do we go from here?
We do not know much about all of the chemicals inside us, around us
Eliminating them may mean other problems.. Costs?
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 MODEL
First: new chemical technologies would be considered harmful until studies say otherwise.
Second: existing chemicals that appear to be harmful would be removed from use.
EU close to adopting this type of approach.
TRANSMITTABLE AND NONTRANSMITTABLE DISEASESNon- transmissible: 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)
REDUCING INFECTIOUS DISEASES
Increase research Reduce poverty Decrease malnutrition Educate people Immunize children
BIOTERRORISM
Possible targets: air, water, and food
InexpensiveFairly easy to produce biological agents
Recombinant DNA techniques
Perfluorochemicals (PFCs) are a group of chemicals used to make fluoropolymer coatings and products that resist heat, oil, stains, grease, and water.