Chapter 14: Environmental Health and Toxicology

1. Chapter 14: Environmental Health and Toxicology www.aw-bc.com/Withgott

2. Environmental Health • assesses environmental factors that influence human health and quality of life • natural • human-caused

3. Physical Hazards • natural disasters • earthquakes • volcanic eruption • fires • floods • blizzards • landslides • hurricanes • droughts • UV radiation • difficult to predict • areas of high risk can be determined

4. Chemical Hazards • synthetic chemicals society produces • disinfectants (Lysol products) • pesticides (DDT)

5. Biological Hazard • ecological interaction between organisms • infectious diseases • swine flu: virus • tuberculosis: bacteria Mycobacterium tuberculosis • malaria: parasite Plasmodium sp. • cholera: bacteria Vibrio cholerae

6. Cultural Hazards • behavioral choices • smoking, sunbathing, drug use • location we live in • near an active volcano Alaskan volcano 2006 apod.nasa.gov/apod/ap060607.html

7. socioeconomic status • Cadillac Heights • occupation • hazardous work or lack of safety equipment www.dallasnews.com Dallas Flood June 2007

8. Disease • major factor of environmental health www.aw-bc.com/Withgott

9. Indoor Health Hazards • radon • highly toxic gas • seeps up from the ground in certain areas • lead • water from lead pipes and lead paint in homes and toys • damages brain, liver, kidney and stomach • learning disabilities • behavioral abnormalities • anemia • hearing loss • death

10. Indoor Health Hazards • asbestos • form long thin microscopic fibers • used in insulation (sound, heat) • resists fire • dangerous when inhaled: asbestosis & cancer • PBDEs • fire-retardant • used in electronics, plastics and furniture • evaporates at very low rates • accumulates in tissues • may affect nervous system and cause cancer • banned in the EU

11. Toxicology • study of poisonous substances • environmental toxicology deals with toxics discharged in the environment • on humans • other animals • ecosystems

12. Environmental Toxicology • natural toxins • radon, arsenic, mercury • exuded substances from plants and animals • human-made toxins • wastewater contaminants • pesticides & herbicides • Silent Spring by naturalist Rachel Carson • effect of DDT on humans, animals and ecosystems • DDT is still in use in tropical areas to control diseases

13. Types of Toxicants • carcinogens • causes cancer • mutagens • causes mutations in fetus • teratogens • affects fetus during gestation causing birth defects • Thalidomide

14. Types of Toxicants • allergens • weakens immune system • increase in asthma • neurotoxins • inorganic: heavy metals (lead, mercury) • Minamata case • organic: pesticides (DDT, mothballs, nerve gas) • some are very stable and can last decades, others may only last hours

15. Types of Toxicants • endocrine disruptors • interfere with hormones • affects growth, reproduction, behavior, brain function • similar to hormones so they "mimic" them • certain pesticides→ feminization of males • possible cause of human sperm count drop worldwide • possible cause of increase rates of • testicular cancer • undescended testicles • genital birth defects in men • female breast cancer

16. www.aw-bc.com/Withgott Effects of Endocrine Disruptors

17. Other Effects of Endocrine Disruptors • brain functioning • PCB contamination of food (fish) • lower birth weight of babies • smaller heads • weak and jerky reflexes • tested poorly in intelligence tests

18. Means of Toxins' Disperse • water • many are soluble in water • runoff • concentrates toxins in surface waterways • enters tissue through drinking or contact • air • pesticide drift • toxins appeared in tissues of arctic polar bears and antarctic penguins • thought to be due to global atmospheric circulation

19. www.aw-bc.com/Withgott • Distribution of Toxins

20. Toxins in the Food Chain • Bioaccumulation • stored in tissues according to its solubility • Biomagnification • increase in toxin concentration up in the food chain • Bald eagle case related to DDT • population decrease of polar bears

21. Epidemiology Studies • application of experimentation due to conditions in the environment • effect of a contaminant in the air to a population already established • drawback • takes too long • many other factors may affect the health of the subjects • statistical association between health hazard and effect but it does not confirm it as the cause of the problem

22. Dose-responce Toxicity • effect of toxins according to amount in the system/body • LD50→ lethal dose for 50% • low LD50 means high mortality • high LD50 means low mortality • ED50→ effective dose for 50% • half of the population gets sick but doesn't die • Threshold • toxin level above which a responce is observed

23. Exposure vs Responce • acute responce • responce to a high exposure during a short period of time • Union Carbide accident in India • chronic responce • responce to a low concentration of a toxin but during a long period of time • exposure to Teflon • synergistic effect • unpredicted consequences of mixing toxins • sum • cancel • multiply or exacerbate

24. Risk Assessment & Risk Management • Assessment: collection and interpretation of scientific data identifying outlining problems • expressed in probability • risk of crashing if driving too fast • Management: formulation of policy to minimize risk • influenced by political pressure • considers economics and ethics • EPA, CDC, FDA • banning of Seldain D • banning of DDT • containing cholera

25. Philosophical Approaches • innocent-until-proven-guilty • innovation goes ahead • doesn't slow down technology • can result in disasters • recall • Vioxx (short period of testing) • vitamins & herbs (unregulated)

26. Philosophical Approaches • harmful until proven otherwise • precaution principle • experimentation has to be done thoroughly • long process] • regulated medications

27. EPA • Federal Insecticide, Fungicide and Rodenticide Act of 1947 assured the effectiveness of the product • EPA was created to protect the public and environment from toxic chemicals using risk assessment and management • EPA examines the data from the manufacture • assesses the possible risks to humans and environment • approves, denies or sets limits to use

28. Toxic Substances Control Act (1976) • regulation of synthetic chemicals by the EPA • criticized as too weak • screening of industry is minimal • EPA needs to show proof of toxicity and not the other way around • only 10% have been tested for toxicity • only 2% have been tested for carcinogens • fewer than 1% are government regulated • none have been tested for endocrine, nervous or immune system damage

29. International Regulation • Stockholm Convention on persistent Organic Pollutants of 2004 • "dirty dozen" • guidelines to phase off these chemicals • REACH pushes innovation of new chemicals to do the same job but be less toxic

30. Dirty Dozen www.aw-bc.com/Withgott The End