1. Human Health and Environmental Risks Chapter 17

2. Categories of Human Health 3 major categories of risks a. physical – natural disasters, radon, UV rays b. biological – “diseases” c. chemical – exposure to chemicals (arsenic)

3. Types of Diseases Infectious diseases a. pathogens b. top 3 1. respiratory infections 2. AIDS 3. diarrhea c. after the top 3 1. tuberculosis 2. malaria 3. measles and tetanus

4. d. chronic v. acute 1. chronic * slowly impairs functioning of body 2. acute * rapidly impairs body 3. risk factors for chronic * differ between income levels

5. Historically Infectious Diseases “passed between hosts” - plague, malaria, tuberculosis Epidemic v. pandemic a. epidemic – rapid increase in disease b. pandemic – epidemic occurs over large region

6. Plague a. “bubonic plague, black death” b. fleas c. transmitted through flea bites d. symptoms - swollen glands, black spots on skin, pain e. treatment - antibiotics

7. Malaria a. Plasmodium b. relies on red blood cells of humans c. flulike symptoms d. sub-Sahara Africa, Asia, Middle East, Central and South America e. US mosquitos have been eradicated of malaria parasite (DDT)

8. Tuberculosis a. highly contagious b. Mycobacterium tuberculosis c. infects the lungs d. spread through coughing e. symptoms - weakness, night sweats, coughing up blood f. treatment - year long antibiotic

9. Emergent Infectious Diseases Arise from pathogens that normally affect animal hosts, now affecting human hosts High-Profile Diseases a. HIV/AIDS 1. Acquired Immune Deficiency Syndrome - rare pneumonia weakening immune systems

10. 2. Human Immunodeficiency Virus - weakened immune system through virus 3. transmitted through sexual contact and drug users (sharing of needles) 4. similar virus in chimps of Cameroon

11. b. Ebola Hemorrhagic Fever 1. caused by the Ebola virus 2. high death rate (50-89%) - occurs within 2 weeks (acute) 3. natural source is unknown - kills primate source too quickly

12. c. Mad Cow Disease 1. neurological disease 2. damaged nervous system 3. 1996 – discovered it can be transmitted to humans - exposed to infected cattle - Creutzfeldt-Jacob Disease

13. d. West Nile Virus 1. transmitted among bird by mosquitos 2. most survive 3. causes inflammation of the brain

14. Future of human health a. low-income country - better nutrition - availability to cleaner drinking water - proper sanitation b. high-income countries - promotion of healthier lifestyle - limit tobacco use

15. Toxicology Harmful chemicals fall into five categories a. neurotoxins 1. disrupts nervous system 2. insecticides 3. lead and mercury - damage to brain, kidneys, and nervous system

16. b. carcinogens 1. cancer causing 2. lead to uncontrolled cell growth - disrupts normal metabolic processes of cell - damages genetic material of cell (mutagen) 3. asbestos, radon, formaldehyde, tobacco

17. c. teratogens 1. interfere with normal development of embryos and fetuses 2. alcohol d. allergens 1. cause allergic reactions

18. e. endocrine disruptors 1. interfere with normal functioning of hormones in the animal’s body 2. hormones released into bloodstream in low concentrations, they bind to cells, and allows cell to regulate body function

19. Assessing Chemical Risks Dose-Response Studies a. animals/plants exposed to various concentrations of a chemical, and then animal/plant’s response is observed (mortality, behavior, reproduction) b. acute studies c. results take on a S-shaped curve (threshold, LD50)

20. d. Conducted on rats and then results are extrapolated to humans e. ED50 1. “effective dose” 2. used for other tests related to other chemicals such as carcinogens, neurotoxins, etc 3. causes 50% of individuals to show the harmful but nonlethal effect of dose

21. Testing Standards a. Toxic Substances Control Act of 1976 - gives EPA authority to regulate many chemicals, excluding food, cosmetics and pesticides b. Federal Insecticide, Fungicide, and Rodenticide Act of 1996 - regulates pesticides - manufacturer must show that the pesticide will not cause unreasonable effects on the environment

22. c. Determining safe levels 1. take the LD50 and ED50 obtained from the rats and divide it by 1,000 Chronic Studies a. over a period of longer duration b. examines long term effects of chemicals such as the effect on survival and impact on reproduction

23. Retrospective v. Prospective Studies a. retrospective 1. monitors people who have been exposed at some point in their past b. prospective 1. monitors people who could possibly be harmed by chemicals in the future 2. synergistic interactions

24. Determination of Concentrations a. routes of exposure b. solubility - biomagnification v. bioaccumulation