RISK, TOXICOLOGY, AND HUMAN HEALTH

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

RISK, TOXICOLOGY, AND HUMAN HEALTH

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

Annual death rates in the U.S. in 2003

Annual death rates in the U.S. in 2011.

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

Physical hazards: fire, tornado, volcanic eruption, earthquake, 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.

Which type of hazard do these fit into?

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.

FRQ WARM UP

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)

Dengue Fever – virus caused disease spread by mosquito

Malaria – parasitic disease spread by mosquitoes

Yellow Fever – Viral disease spread by mosquitoes

TB Kills 1.7 million people per year.

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.

Studies in animals have found some health effects, including changes in liver and thyroid function, increased tumors in certain organs, and reproductive problems.