1. Risk, Toxicology, and Human Health Ch 17 Dr. Richard Clements Chattanooga State Technical Community College Dr. Richard Clements Chattanooga State Technical Community College

2. Key Concepts  Types of hazards people face  Methods of toxicology  Types and measurement of chemical hazards  Types and effects of biological hazards  Risk estimation, management, and reduction

3. Risk and Probability  Risk - the possibility of suffering harm from exposure to a hazard that can cause injury, disease, economic loss, or environmental damage.  probability: a mathematical statement about how likely it is that some event or effect will occur.  Risk - the possibility of suffering harm from exposure to a hazard that can cause injury, disease, economic loss, or environmental damage.  probability: a mathematical statement about how likely it is that some event or effect will occur. Risk assessment involves using data, hypotheses, and models to estimate: a.What is the hazard? b.Probability that harm will occur c.How much damage is likely to occur Risk assessment involves using data, hypotheses, and models to estimate: a.What is the hazard? b.Probability that harm will occur c.How much damage is likely to occur

4. Risk and Probability  Risk management - making decisions by a.Comparing with other risks b.Assessing how risk can be reduced if needed c.Calculating financial commitment necessary  Risk management - making decisions by a.Comparing with other risks b.Assessing how risk can be reduced if needed c.Calculating financial commitment necessary

5. Hazards  Cultural hazards - such as unsafe working conditions, diet, drugs, drinking, poverty  Cultural hazards - such as unsafe working conditions, diet, drugs, drinking, poverty  Chemical hazards - from harmful chemicals (such as, in the air, water, soil).  Chemical hazards - from harmful chemicals (such as, in the air, water, soil).  Physical hazards - (ex: ionizing radiation, fire, hurricanes).  Physical hazards - (ex: ionizing radiation, fire, hurricanes).  Biological hazards - from pathogens (disease causing organisms such as bacteria, viruses & parasites), allergens (such as pollen, mold), and animals (such as bees, poisonous snakes).  Biological hazards - from pathogens (disease causing organisms such as bacteria, viruses & parasites), allergens (such as pollen, mold), and animals (such as bees, poisonous snakes).

6. Toxicology  Toxicity - measure of how harmful a substance is.  Toxicity - measure of how harmful a substance is.  Dosage - The amount of a potentially harmful substance that a person has ingested, inhaled, or absorbed through the skin  Dosage - The amount of a potentially harmful substance that a person has ingested, inhaled, or absorbed through the skin

7. © 2004 Brooks/Cole – Thomson Learning Very sensitive Majority of population Very insensitive 020406080 Dose (hypothetical units) Number of individuals affected

8. Response The resulting type and amount of damage to health Depends on: a.size of the dose over a period of time b.how often exposure occurs c.who is exposed (ex: child, adult) d.How well liver, lungs and kidneys work to detoxify the substance e.Genetic makeup that determines an individuals sensitivity

9. Toxicology  Bioaccumulation - an increase in the concentration of a chemical in specific organs or tissues at a level higher than would normally be expected.  Bioaccumulation - an increase in the concentration of a chemical in specific organs or tissues at a level higher than would normally be expected.  Biomagnification  The levels of some toxins stored in body fat can also be magnified as they pass through food chains and webs. Ex: DDT – pesticide, PCB’s – oily chemicals used in electrical transformers, some radioactive isotopes  Biomagnification  The levels of some toxins stored in body fat can also be magnified as they pass through food chains and webs. Ex: DDT – pesticide, PCB’s – oily chemicals used in electrical transformers, some radioactive isotopes Persistence of substance – resistance to breakdown determines how long it will persist in the environment or body. Ex: CFC’s and chlorinated hydrocarbons have a long-lasting affect on people and wildlife.

10. DDT in fish-eating birds (ospreys) 25 ppm DDT in large fish (needle fish) 2 ppm DDT in small fish (minnows) 0.5 ppm DDT in zooplankton 0.04 ppm DDT in water 0.000003 ppm, Or 3 ppt

11. Toxicology  Synergism - Chemical interactions can decrease or multiply harmful effects: Antagonistic interactions – reduce harmful response Ex: vitamins A & E reduce response of some carcinogens. Synergistic interactions – increase harmful response Ex: asbestos exposure and cigarette smoking together increase chances of getting lung cancer above each substance alone.  Synergism - Chemical interactions can decrease or multiply harmful effects: Antagonistic interactions – reduce harmful response Ex: vitamins A & E reduce response of some carcinogens. Synergistic interactions – increase harmful response Ex: asbestos exposure and cigarette smoking together increase chances of getting lung cancer above each substance alone.  Acute effect - immediate harmful reaction  Chronic effect - permanent or long lasting effect.  Chronic effect - permanent or long lasting effect.

12. Poisons  Poison - chemical that has an LD 50 of 50 milligrams or less per kilogram of body weight.  Poison - chemical that has an LD 50 of 50 milligrams or less per kilogram of body weight.  LD 50 - median lethal dose, or amount of a chemical received in one dose that kills exactly 50% of the animals in a test population within a 14-day period.  LD 50 - median lethal dose, or amount of a chemical received in one dose that kills exactly 50% of the animals in a test population within a 14-day period.

13. 100 75 50 25 0 24 6 8 10 12 14 16 Percentage of population killed by a given dose Dose (hypothetical units) LD 50 © 2004 Brooks/Cole – Thomson Learning

14. How much is too much? Threshold level – below this amount, harmful effects are insignificant. Why? 1.Human body has ways of breaking down (usually by liver enzymes), diluting or excreting small amts. of most toxins to keep them from reaching harmful levels. 2.Individual cells have enzymes that can repair damage to DNA and proteins. 3.Cells in some parts of the body (ex: skin, intestines) reproduce fast enough to replace damaged cells. But exposure to carcinogens accelerates cell growth and creates tumors. 4.Detection methods have become increasingly more sensitive – in 1980 chemists could detect concentrations in ppm (parts per million), in 1990 in ppb (ppbillion), and today ppt (pptrillion) or sometimes ppq (ppquadrillion).

15. Dose-Response Curves  Nonthreshold - any dose of a toxic chemical or ionizing radiation has a certain risk of causing harm.  Nonthreshold - any dose of a toxic chemical or ionizing radiation has a certain risk of causing harm.  Threshold there is a threshold dose below which no detectable harmful effects occur, presumably because the body can repair the damage caused by low doses of some substances.  Threshold there is a threshold dose below which no detectable harmful effects occur, presumably because the body can repair the damage caused by low doses of some substances.

16. © 2004 Brooks/Cole – Thomson Learning Effect Dose Nonlinear dose-response Linear dose-response No threshold Effect Nonlinear dose-response Linear dose-response Threshold level Dose

17. Chemical Hazards Types of Hazardous chemicals  Mutagens - are agents, such as chemicals and radiation, that cause mutations, or changes in the DNA molecules found in the cells. Mutations to gametes can cause diseases such as bipolar disorder, cystic fibrosis, hemophilia, sickle-cell anemia, susceptibility to some types of cancers in offspring. Most mutations are actually harmless and some play a vital role in microevolution.  Mutagens - are agents, such as chemicals and radiation, that cause mutations, or changes in the DNA molecules found in the cells. Mutations to gametes can cause diseases such as bipolar disorder, cystic fibrosis, hemophilia, sickle-cell anemia, susceptibility to some types of cancers in offspring. Most mutations are actually harmless and some play a vital role in microevolution.

18. Chemical Hazards Types of Hazardous chemicals Teratogens - are chemicals, radiation, or viruses that cause birth defects while the human embryo is growing and developing during pregnancy, especially during the first 3 months. Carcinogens - are chemicals, radiation, or viruses that cause or promote the growth of malignant tumor, in which certain cells multiply uncontrollably. Teratogens - are chemicals, radiation, or viruses that cause birth defects while the human embryo is growing and developing during pregnancy, especially during the first 3 months. Carcinogens - are chemicals, radiation, or viruses that cause or promote the growth of malignant tumor, in which certain cells multiply uncontrollably.

19. Chemical Hazards  Neurotoxins Ex: 1.chlorinated hydrocarbons (DDT, PCBs, dioxins) 2.organophosphate pesticides 3.formaldehyde, compounds of arsenic, mercury, lead, and cadmium 4.some widely used industrial solvents such as trichloroethylene (TCE), toluene, and xylene.  Neurotoxins Ex: 1.chlorinated hydrocarbons (DDT, PCBs, dioxins) 2.organophosphate pesticides 3.formaldehyde, compounds of arsenic, mercury, lead, and cadmium 4.some widely used industrial solvents such as trichloroethylene (TCE), toluene, and xylene.

20. Case Study: PCBs Are Everywhere— Class of chlorine-containing compounds (Polychlorinated Biphenyl ) – can enter the air as vapor –Were widely used as lubricants, hydraulic fluids, electrical insulators in transformers, in paints, pesticides, fire retardants in fabrics, preservatives, adhesives. –Carcinogen, also affects reproductive, nervous, endocrine, immune system. –Banned in 1979 in the U.S. –Highly persistent, Fat soluble – Biomagnification Banned, but found everywhere

21. Science Focus: Mercury’s Toxic Effects (2) How are humans exposed? –Inhalation: vaporized Hg or particulates of inorganic salts –Eating fish with high levels of methylmercury Effects of Hg on humans – Neurotoxin that causes brain damage, esp in developing fetuses Case Study – Minimata Bay, Japan

22. Fig. 17-A, p. 450 WINDSPRECIPITATIONWINDSPRECIPITATION Hg and SO 2 Hg 2+ and acids Photo- chemical oxidation Human sources Elemental mercury vapor (Hg) Inorganic mercury and acids (Hg 2+ ) Inorganic mercury and acids (Hg 2+ ) Coal- burning plant Deposition Incinerator Vaporization Large fish Deposition Small fish BIOMAGNIFICATION IN FOOD CHAIN Zooplankton Phytoplankton Bacteria and acids Elemental mercury liquid (Hg) Oxidation Inorganic mercury (Hg 2+ ) Organic mercury (CH 3 Hg + ) Bacteria Settles out SEDIMENT Runoff of Hg 2+ and acids

23. Fig. 17-B, p. 451 SOLUTIONS Mercury Pollution PreventionControl Phase out waste incinerationSharply reduce mercury emissions from coal-burning plants and incinerators Remove mercury from coal before it is burned Tax each unit of mercury emitted by coal-burning plants and incinerators Switch from coal to natural gas and renewable energy resources such as wind, solar cells, and hydrogen Require labels on all products containing mercury Convert coal to liquid or gaseous fuel Phase out use of mercury in batteries, TVs, compact fluorescent lightbulbs, and all other products unless they are recycled Collect and recycle mercury- containing electric switches, relays, and dry-cell batteries

24. Bisphenol A Used in plastic food containers (#7) Many studies find no effects Precautionary principle

25. Chemical Hazards  Hormonally active agents ( HAA’s) Low levels of synthetic chemical agents that can mimic and disrupt effects of natural hormones. Ex: PCBs, DDT Hormone mimics - are estrogen-like chemicals that disrupt the endocrine system by being able to attach to estrogen receptor molecules. Hormone blockers - disrupt the endocrine system by preventing hormones (such as androgens) from attaching to their receptors. thyroid disruptors and cause growth, weight gain, and behavioral disorders.  Hormonally active agents ( HAA’s) Low levels of synthetic chemical agents that can mimic and disrupt effects of natural hormones. Ex: PCBs, DDT Hormone mimics - are estrogen-like chemicals that disrupt the endocrine system by being able to attach to estrogen receptor molecules. Hormone blockers - disrupt the endocrine system by preventing hormones (such as androgens) from attaching to their receptors. thyroid disruptors and cause growth, weight gain, and behavioral disorders.

26. Hormone Receptor Cell Normal Hormone ProcessHormone MimicHormone Blocker Estrogen-like chemicalAntiandrogen chemical Figure 11-7 Page 234

27. What should we do? Precautionary principle 1.Emphasizes pollution prevention! 2.When we are uncertain about potentially serious harm from something, decision makers should act to prevent harm to humans and the environment. (“better safe than sorry” 3. New chemicals and technologies would be assumed guilty until proven innocent those proposing to introduce a new chemical or technology would bear the burden of establishing it’s safety Precautionary principle 1.Emphasizes pollution prevention! 2.When we are uncertain about potentially serious harm from something, decision makers should act to prevent harm to humans and the environment. (“better safe than sorry” 3. New chemicals and technologies would be assumed guilty until proven innocent those proposing to introduce a new chemical or technology would bear the burden of establishing it’s safety

28. Biological Hazards: Diseases  Nontransmissible disease  Transmissible disease  Pathogens  Vectors  Antibiotic resistance See Case Study p. 241  Malaria  AIDS

29. Figure 11-12 Page 243 Malaria-free areasMalaria largely eliminatedMalaria transmission areas

30. Risk Analysis  Risk analysis  Comparative risk analysis  Cost-benefit analysis  Risk management  Risk perception Fig. 11-17 p. 247