Chapter 8 - O'Neill PPoint


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Chapter 8 - O'Neill PPoint

  1. 1. Environmental Health and Toxicology
  2. 2. Outline <ul><li>Environmental Health </li></ul><ul><ul><li>Infectious and Emergent Diseases </li></ul></ul><ul><ul><li>Antibiotics and Pesticide Resistance </li></ul></ul><ul><li>Toxicology </li></ul><ul><li>Movement, Distribution, and Fate of Toxins </li></ul><ul><li>Minimizing Toxic Effects </li></ul><ul><li>Measuring Toxicity </li></ul><ul><li>Risk Assessment </li></ul><ul><li>Establishing Public Policy </li></ul>
  3. 3. ENVIRONMENTAL HEALTH <ul><li>Health </li></ul><ul><ul><li>A state of complete physical, mental, and social well-being. </li></ul></ul><ul><li>Disease </li></ul><ul><ul><li>A deleterious change in the body’s condition in response to an environmental factor. </li></ul></ul><ul><ul><li>Diet and nutrition, infectious agents, toxic chemicals, physical factors, and psychological stress all play roles in morbidity (illness) and mortality (death). </li></ul></ul>
  4. 4. Environmental Health Risks
  5. 5. Global Disease Burden <ul><li>Disability-adjusted life years </li></ul><ul><ul><li>(DALYs) - combine premature deaths and loss of healthy life resulting from illness or disability </li></ul></ul><ul><li>Life expectancy has risen worldwide; chronic conditions are becoming a leading cause of disability and premature death. </li></ul><ul><ul><li>By 2020, heart disease may become leading source of disability and disease worldwide. </li></ul></ul>
  6. 6. Recent Outbreaks of Infectious Diseases
  7. 7. Infectious Diseases <ul><li>Greatest health threats: </li></ul><ul><ul><li>pathogenic organisms, accidents or violence. </li></ul></ul><ul><ul><li>Communicable diseases </li></ul></ul><ul><ul><ul><li>responsible for about 1/3 of all disease-related deaths. </li></ul></ul></ul><ul><ul><ul><li>Majority in countries with poor nutrition, sanitation, and vaccination programs. </li></ul></ul></ul><ul><ul><ul><ul><li>Malaria is a major disease in tropical areas. </li></ul></ul></ul></ul>
  8. 8. Emergent Diseases <ul><li>An emergent disease: </li></ul><ul><ul><ul><li>never known before </li></ul></ul></ul><ul><ul><ul><li>been absent for at least 20 years. </li></ul></ul></ul><ul><ul><li>The spread of many diseases </li></ul></ul><ul><ul><ul><li>is due to the speed and frequency of modern travel </li></ul></ul></ul><ul><ul><ul><ul><li>Ex. SARS </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Ex. West Nile Virus </li></ul></ul></ul></ul>
  9. 9. Funding Health Care <ul><li>Heaviest burden of illness borne by poorest people who cannot afford a healthy environment or adequate health care. </li></ul><ul><ul><li>WHO estimates 90% of all disease burden occurs in developing countries where less than 10% of all health care dollars are spent. </li></ul></ul><ul><ul><ul><li>Worldwide, only 2% of people with AIDS have access to modern medicines. </li></ul></ul></ul>
  10. 10. Ecological Diseases <ul><li>Domestic animals and wildlife also experience sudden and widespread epidemics. </li></ul><ul><ul><li>Distemper in seals in western Europe. </li></ul></ul><ul><ul><li>Chronic Wasting Disease in deer and elk in North America </li></ul></ul><ul><ul><li> </li></ul></ul><ul><ul><li>Sudden Oak Death Syndrome in California. </li></ul></ul>
  11. 11. Antibiotic and Pesticide Resistance <ul><li>The problem with antibiotics and pesticides: </li></ul><ul><li>Protozoan parasite that causes malaria is now resistant to most antibiotics, while the mosquitoes that transmit it have developed resistance to many insecticides. </li></ul><ul><ul><li>Short life spans. </li></ul></ul><ul><ul><ul><li>Speeds up natural selection and evolution. </li></ul></ul></ul><ul><ul><li>Human tendency to overuse pesticides and antibiotics. </li></ul></ul>
  12. 12. Antibiotic Use <ul><li>Why is antibiotic use a problem? </li></ul><ul><ul><li>At least half of the 100 million antibiotic doses prescribed in the US every year are unnecessary or are the wrong drug. </li></ul></ul><ul><ul><li>Many people do not finish full-course. </li></ul></ul><ul><ul><li>More than half of all antibiotics manufactured in the US are routinely fed to farm animals to stimulate weight gain. </li></ul></ul>
  13. 13. Antibiotic Resistance – How is it developed?
  14. 14. Toxicology <ul><li>Dangerous chemicals are divided into two broad categories: </li></ul><ul><ul><li>Toxic - Poisonous </li></ul></ul><ul><ul><ul><li>Can be general or very specific. Often harmful even in dilute concentrations. </li></ul></ul></ul><ul><ul><li>Hazardous - Dangerous </li></ul></ul><ul><ul><ul><li>Flammable, explosive, irritant, acid, caustic. </li></ul></ul></ul>
  15. 15. Toxic Chemicals <ul><li>Allergens </li></ul><ul><ul><li>Substances that activate the immune system. </li></ul></ul><ul><ul><li>Antigens </li></ul></ul><ul><ul><ul><li>Allergens that are recognized as foreign by white blood cells and stimulate the production of specific antibodies. </li></ul></ul></ul><ul><ul><ul><ul><li>Other allergens act indirectly by binding to other materials so they become antigenic. </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Sick Building Syndrome </li></ul></ul></ul></ul></ul>
  16. 16. Toxic Chemicals <ul><li>Endocrine Disrupters </li></ul><ul><ul><li>Disrupt normal hormone functions </li></ul></ul><ul><ul><ul><li>Thyroxine </li></ul></ul></ul><ul><ul><ul><ul><li>Regulates cell metabolism </li></ul></ul></ul></ul><ul><ul><ul><li>Insulin </li></ul></ul></ul><ul><ul><ul><ul><li>regulates blood sugar levels </li></ul></ul></ul></ul><ul><ul><ul><li>Adrenalin </li></ul></ul></ul><ul><ul><ul><ul><li>response to stress; stimulates autonomic nerve action </li></ul></ul></ul></ul><ul><ul><ul><li>Endorphins </li></ul></ul></ul><ul><ul><ul><ul><li>reduce the sensation of pain and affect emotions </li></ul></ul></ul></ul>
  17. 17. Steroid Hormone Action Normal: Hormone carriers deliver molecules to cell surface. Intraceullur carriers deliver hormones to the nucleus; bind to and regulate expression of DNA.
  18. 18. Toxic Chemicals <ul><li>Neurotoxins </li></ul><ul><ul><li>Metabolic poisons that specifically attack nerve cells. </li></ul></ul><ul><ul><li>Different types act in different ways. </li></ul></ul><ul><ul><ul><li>Heavy Metals kill nerve cells. </li></ul></ul></ul><ul><ul><ul><li>Anesthetics and Chlorinated Hydrocarbons disrupt nerve cell membranes. </li></ul></ul></ul><ul><ul><ul><li>Organophosphates and Carbamates inhibit signal transmission between nerve cells. </li></ul></ul></ul>
  19. 19. Toxic Chemicals <ul><li>Mutagens </li></ul><ul><ul><li>Agents that damage or alter genetic material. </li></ul></ul><ul><ul><ul><li>Ex. Radiation </li></ul></ul></ul><ul><li>Teratogens </li></ul><ul><ul><li>Specifically cause abnormalities during embryonic growth and development. </li></ul></ul><ul><ul><ul><li>Alcohol - Fetal Alcohol Syndrome </li></ul></ul></ul><ul><li>Carcinogens </li></ul><ul><ul><li>Substances that cause cancer. </li></ul></ul><ul><ul><ul><li>Ex. Cigarette smoke </li></ul></ul></ul>
  20. 20. Diet <ul><li>Sixty-percent of all U.S. adults are now considered overweight. </li></ul><ul><ul><li>Estimated 1 billion worldwide. </li></ul></ul><ul><li>U.S. Centers for Disease Control warn one in three U.S. children are at risk of becoming diabetic. </li></ul>
  21. 21. MOVEMENT, DISTRIBUTION, AND FATE OF TOXINS <ul><li>Solubility </li></ul><ul><ul><li>One of most important characteristics in determining the movement of a toxin. </li></ul></ul><ul><li>Chemicals are divided into two major groups: </li></ul><ul><ul><ul><li>Those that dissolve more readily in water. </li></ul></ul></ul><ul><ul><ul><li>Those that dissolve more readily in oil. </li></ul></ul></ul><ul><ul><li>What’s the difference in how they move? </li></ul></ul><ul><ul><ul><li>Water soluble compounds move rapidly through the environment, and have ready access to most human cells. </li></ul></ul></ul>
  22. 22. The movement and fate of chemicals in the environment.
  23. 23. Exposure and Susceptibility <ul><li>How and where do they affect us? </li></ul><ul><ul><li>Airborne toxins generally cause more ill health than any other exposure. </li></ul></ul><ul><ul><ul><li>Lining of lungs easily absorbs toxins. </li></ul></ul></ul><ul><ul><li>Largest toxin exposure reported in industrial settings. </li></ul></ul><ul><ul><li>Condition of organism and timing of exposure also have strong influences on toxicity. </li></ul></ul>
  24. 24. Exposure Routes Exposure routes to toxic and hazardous environmental factors
  25. 25. Bioaccumulation and Biomagnification <ul><li>Cells have special mechanisms for: Bioaccumulation </li></ul><ul><ul><li>Selective absorption and storage. </li></ul></ul><ul><ul><ul><li>Dilute toxins in the environment can build to dangerous levels inside cells and tissues. </li></ul></ul></ul><ul><li>Biomagnification </li></ul><ul><ul><li>Toxic burden of a large number of organisms at a lower trophic level is accumulated and concentrated by a predator at a higher trophic level. </li></ul></ul>
  26. 26. Bioaccumulation and Biomagnification
  27. 27. Persistence <ul><li>Some chemical compounds are very unstable and degrade rapidly under most conditions, thus their concentrations decline quickly after release. </li></ul><ul><li>Others are more persistent. </li></ul><ul><ul><li>Stability can cause problems as toxic effects may be stored for long period of time and spread to unintended victims. </li></ul></ul><ul><ul><ul><li>Example? </li></ul></ul></ul><ul><ul><ul><ul><li>(DDT) </li></ul></ul></ul></ul>
  28. 28. Persistence <ul><li>Persistent Organic Pollutants ( POP’s ) </li></ul><ul><ul><li>Polybrominated diphenyl ethers (PDBE) </li></ul></ul><ul><ul><li>Perfluorooctane sulfonate (PFOS) and Perfluorooctanic acid (PFOA). </li></ul></ul><ul><ul><li>Phthalates </li></ul></ul><ul><ul><li>Perchlorate </li></ul></ul><ul><ul><li>Bisphenol A (BPA) </li></ul></ul><ul><ul><li>Atrazine </li></ul></ul>
  29. 29. Chemical Interactions <ul><li>Antagonistic Reaction : </li></ul><ul><ul><li>One material interferes with the effects, or stimulates the breakdown, of other chemicals. </li></ul></ul><ul><li>Additive Reaction </li></ul><ul><ul><li>Effects of each chemical are added to one another. </li></ul></ul><ul><li>Synergistic Reaction </li></ul><ul><ul><li>One substance exacerbates the effect of the other. </li></ul></ul>
  30. 30. MECHANISMS FOR MINIMIZING TOXIC EFFECTS <ul><li>Every material can be poisonous under certain conditions. </li></ul><ul><ul><li>Most chemicals have a safe threshold under which their effects are insignificant. </li></ul></ul><ul><li>Metabolic Degradation </li></ul><ul><ul><li>In mammals, the liver is the primary site of detoxification of both natural and introduced poisons. </li></ul></ul>
  31. 31. Excretion and Repair <ul><li>Effects of waste products and environmental toxins reduced by eliminating via excretion. </li></ul><ul><ul><li>Breathing </li></ul></ul><ul><ul><li>Kidneys </li></ul></ul><ul><ul><ul><li>Urine </li></ul></ul></ul><ul><li>Tissues and organs often have mechanisms for damage repair. </li></ul><ul><ul><li>Any irritating agent can be potentially carcinogenic. </li></ul></ul>
  32. 32. MEASURING TOXICITY <ul><li>Animal Testing </li></ul><ul><ul><li>Most commonly used and widely accepted toxicity test is to expose a population of laboratory animals to measured doses of specific toxins. </li></ul></ul><ul><ul><ul><li>Sensitivity differences pose a problem. </li></ul></ul></ul><ul><ul><ul><ul><li>Dose Response Curves </li></ul></ul></ul></ul><ul><ul><ul><ul><li>LD50 - Dose at which 50% of the test population is sensitive. </li></ul></ul></ul></ul>
  33. 33. Toxicity Ratings <ul><li>Moderate toxin takes about (1) g/kg of body weight to produce a lethal dose. </li></ul><ul><ul><li>Very toxic materials require about 10% of that amount. </li></ul></ul><ul><ul><ul><li>Extremely toxic materials require 1% of that amount. </li></ul></ul></ul><ul><ul><ul><ul><li>Supertoxic chemicals can be lethal in a dose of a few micrograms. </li></ul></ul></ul></ul>
  34. 34. Toxicity Ratings <ul><li>Many carcinogens, mutagens, and teratogens are dangerous at levels far below their direct toxic effect because abnormal cell growth exerts a form of biological amplification. </li></ul>
  35. 35. Acute versus Chronic Doses and Effects <ul><li>Acute Effects </li></ul><ul><ul><li>Caused by a single exposure and result in an immediate health problem. </li></ul></ul><ul><li>Chronic Effects </li></ul><ul><ul><li>Long-lasting. Can be result of single large dose or repeated smaller doses. </li></ul></ul><ul><ul><ul><li>Very difficult to assess specific health effects due to other factors. </li></ul></ul></ul>
  36. 36. RISK ASSESSMENT AND ACCEPTANCE <ul><li>Risk </li></ul><ul><ul><li>Possibility of suffering harm or loss. </li></ul></ul><ul><li>Risk Assessment </li></ul><ul><ul><li>Scientific process of estimating the threat that particular hazards pose to human health. </li></ul></ul><ul><ul><ul><li>Risk Identification </li></ul></ul></ul><ul><ul><ul><li>Dose Response Assessment </li></ul></ul></ul><ul><ul><ul><li>Exposure Appraisal </li></ul></ul></ul><ul><ul><ul><li>Risk Characterization </li></ul></ul></ul>
  37. 38. Understanding Risks <ul><li>Factors influencing risk perception: </li></ul><ul><ul><li>Rating risks based on agendas. </li></ul></ul><ul><ul><li>Most people have trouble with statistics. </li></ul></ul><ul><ul><li>Personal experiences can be misleading. </li></ul></ul><ul><ul><li>We have an exaggerated view of our abilities to control our fate. </li></ul></ul><ul><ul><li>News media sensationalizes rare events. </li></ul></ul><ul><ul><li>Irrational fears lead to overestimation of certain dangers. </li></ul></ul><ul><ul><ul><li>Fear of the unknown. </li></ul></ul></ul>
  38. 39. Accepting Risks <ul><li>Most people will tolerate a higher probability of occurrence of an event if the harm caused by that event is low. </li></ul><ul><ul><li>Harm of greater severity is acceptable only at low levels of frequency. </li></ul></ul><ul><ul><ul><li>EPA generally assumes 1 / 1 million is acceptable risk for environmental hazards. </li></ul></ul></ul>
  39. 40. ESTABLISHING PUBLIC POLICY <ul><li>It is difficult to separate the effects of multiple hazards and evaluate their risks accurately, especially when exposures are near the threshold of measurement and response. </li></ul><ul><ul><li>May not be reasonable to mandate protection, no matter how small the risk, from every potentially harmful contaminant in our environment. </li></ul></ul>
  40. 41. CERCLA and RCRA <ul><li>Remaining Slides are in reference to CERCLA and RCRA </li></ul>
  41. 42. Hazardous Waste <ul><li>Legally, hazardous waste is any discarded liquid or solid that contains substances known to be: </li></ul><ul><ul><li>Fatal to humans or laboratory animals in low doses. </li></ul></ul><ul><ul><li>Toxic, carcinogenic, mutagenic, or teratogenic to humans or other life-forms. </li></ul></ul><ul><ul><li>Ignitable with a flash point less than 60 o C. </li></ul></ul><ul><ul><li>Explosive or highly reactive. </li></ul></ul>
  42. 43. Hazardous Waste Disposal <ul><li>Federal Legislation </li></ul><ul><ul><li>Resource Conservation and Recovery Act (RCRA) - 1976. </li></ul></ul><ul><ul><ul><li>Comprehensive program requiring rigorous testing and management of toxic and hazardous substances. </li></ul></ul></ul><ul><ul><ul><ul><li>Cradle to grave accounting. </li></ul></ul></ul></ul>
  43. 44. Federal Legislation <ul><li>Comprehensive Environmental Response, Compensation and Liability Act (CERCLA). </li></ul><ul><ul><li>Modified in 1984 by Superfund Amendments and Reauthorization Act. </li></ul></ul><ul><ul><ul><li>Aimed at rapid containment, cleanup, or remediation of abandoned toxic waste sites. </li></ul></ul></ul><ul><ul><ul><ul><li>Toxic Release Inventory - Requires 20,000 manufacturing facilities to report annually on releases of more than 300 toxic materials. </li></ul></ul></ul></ul>
  44. 45. Cradle to Grave
  45. 46. CERCLA <ul><li>Government does not have to prove anyone violated a law, or what role they played in a superfund site. </li></ul><ul><ul><li>Liability under CERCLA is “strict, joint, and several”, meaning anyone associated with a site can be held responsible for the entire clean-up cost. </li></ul></ul>
  46. 47. Superfund Sites <ul><li>EPA estimates 36,000 seriously contaminated sites in the U.S.. </li></ul><ul><ul><li>By 1997, 1,400 sites had been placed on the National Priority List for cleanup with with Superfund financing. </li></ul></ul><ul><ul><ul><li>Superfund is a revolving pool designed to: </li></ul></ul></ul><ul><ul><ul><ul><li>Provide immediate response to emergency situations posing imminent hazards. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Clean-up abandoned or inactive sites. </li></ul></ul></ul></ul>
  47. 48. Summary <ul><li>Environmental Health </li></ul><ul><ul><li>Infectious and Emergent Diseases </li></ul></ul><ul><ul><li>Antibiotics and Pesticide Resistance </li></ul></ul><ul><li>Toxicology </li></ul><ul><li>Movement, Distribution, and Fate of Toxins </li></ul><ul><li>Minimizing Toxic Effects </li></ul><ul><li>Measuring Toxicity </li></ul><ul><li>Risk Assessment </li></ul><ul><li>Establishing Public Policy </li></ul>