Understanding Risks and Toxicology in Human Health

1. Risk, Toxicology, and Human Health

2. Warm Up 2/19/2015 • What do you think is the single biggest threat to your life? • What do you think is the single biggest threat to a teenager in a developing country? • What do you think is the single biggest threat to someone of my generation?

3. Risk, Toxicology, and Human Health

4. Ordering of Perceived Risk

5. Annual death rates in the U.S. in 2003

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

7. Risk, Probability and Hazards Risk: 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.

8. 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

9. Cultural hazards: working conditions, diet, driving, • unsafe sex, poverty, etc. Hazards: Types of Risk

10. Physical hazards: fire, tornado, volcanic eruption, earthquake, etc. Hazards: Types of Risk

11. Chemical hazards: harmful chemicals in the air, water, soil and food. • Example: DDT or PCBs Hazards: Types of Risk

12. Biological hazards: pathogens (bacteria, virus, parasites), pollen, animals, plants. Hazards: Types of Risk

13. Which type of hazard do these fit into?

14. TOXICOLOGY: Assessing Chemical Hazards Toxicity: measure of how harmful a substance is in causing injury, illness, or death to living organisms.

15. TOXICOLOGY: Varying facotrs 1) 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

16. Factors Affecting Harm Caused By A Substance • Solubility • Water soluble toxins • move through environment easily • Fat soluble • can accumulate in body tissue and cells

17. Factors Affecting Harm Caused By A Substance 2) Persistence - how long before it breaks down • Bioaccumulation – some molecules are absorbed and stored in specific organs or tissues at higher than normal levels

18. 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)

21. 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.

22. 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

23. Principles of Toxicology Any 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?

24. 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.

26. 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.

27. Factors affecting toxicity of a chemical • Dose • Age • Immune System • Genetic Makeup • Exposure • Solubility • Persistence (bioaccumulation) • Biomagnification • Chemical Interactions

28. 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.

29. Principles of Toxicology Any 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?

30. Median lethal dose (LD50): at this dosage the toxin kill 50% of animals • (usually mice or rats) Poisons

31. Threshold – The dose below which no toxic effects are observed and/or above which the toxic effects are apparent Poisons

32. Principles of Toxicology How do scientists determine toxicity: • Epidemiologic case studies • Animal Testing • Computer modeling

33. 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.

34. 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.

35. 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)

36. Types of Toxic Agents Carcinogens: cause cancer (growth of cancerous tumors) Ex. Benzene (chemical solvent)

37. Warm Up 2/24/2014 • Give an example of a: • Biological hazard • Chemical hazard • Physical hazard • Cultural hazard • What is the difference between a mutagen, teratogen, and carcinogen • Explain what LD50 means.

38. Median lethal dose (LD50): at this dosage the toxin kill 50% of animals • (usually mice or rats) Poisons

39. Impacts of Chemicals on Humans Chemicals may also impact: • Immune system (arsenic, dioxin) • NervousSystem(neurotoxins, brain, spinal cord) • Endocrine System (levels of hormones)

40. 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

41. Hormonally Active Agents Exposure to low level certain synthetic chemicals may disrupt a bodies hormone levels • Endocrine disrupters or hormonally active agents • Ex: BisphenolA (BPA)

42. Establishing Guilt Is Difficult Under 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.

43. FRQ Warm UP

44. 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.

45. Establishing Guilt Is Difficult Why are not all chemicals tested? • Not required (considered innocent) • Lack of funds, personnel, facilities • Expensive • Difficult to test interactions

46. Pollution Prevention Model Where 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

47. 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”

48. 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.

49. Transmittable and Nontransmittable Diseases Non- 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)

50. Dengue Fever – virus caused disease spread by mosquito