Environmental Hazards and Human Health

1. Environmental Hazards and Human Health Chapter 17

2. Some Definitions • Environment: combination of physical, chemical, biological, cultural, and personal choice factors • Hazard: anything that can cause injury, death, disease, damage to personal/public property, or deterioration or destruction of environmental components • Risk: probability of suffering a loss as a result of exposure to a hazard

3. The Picture of Health: Some Terms • Morbidity: incidence of disease in a population • Mortality: incidence of death in a population • Epidemiology: study of presence, distribution, and control of disease in a population

4. Causes of Human Mortality

5. Loss of Life Expectancy from Various Risks

6. Environmental Hazards • Physical • Biological • Chemical • Cultural • Personal Choices

7. Physical Hazards • Natural disasters, e.g., tornadoes, floods, hurricanes, and wildfires • Avoidance of risk important in prevention, e.g., building homes in floodplains, and living on the coast • Climate change: consequences of elevated greenhouse gases

8. Biological Hazards • Pathogenic bacteria • Cholera, Tuberculosis, Streptococcus, Anthrax, Bubonic Plague • Developing genetic resistance (Staphylococcus aureus) • Rapid reproduction, easily spread • Overuse of Antibiotics and Antibacterial products • Overuse of Pesticides • Fungi • black mold, cryptococcus • Viruses • Influenza, HIV/AIDS, Malaria, Smallpox, Typhoid, Ebola • Protozoans • Giardia, Ameoba • Worms • Hook worms, tape worms, Guinea worms

9. Infectious Diseases • Major Health Threat • Spread through Air, Water, Food & Bodily Fluids • Epidemics & Pandemics • Resistant bacteria & insects • Since 1950 • Death from infectious diseases have declined • Better Health Care • Antibiotics • Vaccines

10. The Most Deadly Viral Diseases • Influenza • #1 Killer • Rapid Transmission • Airborne • Contact • Global Efforts • Vaccines • Tracking the virus • Education • HIV/AIDS • #2 Killer • Sexually transmitted • Slow to develop symptoms • Global Efforts • Antiviral drugs (Free/low cost) • Reduce new infections • Concentrate on those most likely to spread HIV • Free Testing • Education • Research

11. Global Map of Tuberculosis, 2001 • Why is tuberculosis on the rise? • Not enough screening and control programs • Genetic resistance to a majority of effective antibiotics • Person-to-person contact has increased • AIDS individuals are very susceptible to TB

12. Infectious Diseases • More prevalent in, but not exclusive to, developing countries • Contamination of food and water • Lack of resources for sanitation • Lack of education • Ideal climates for transmission of vector-borne diseases like malaria

13. Malarial Parasite Life Cycle • Malaria on the rise since 1970 • Drug Resistant Plasmodium • Insecticide Resistance Mosquitoes • Warmer Global temperatures • AIDS individuals very vulnerable

14. Worldwide Distribution of Malaria

15. Other Prevalent & Well-Know Viral Diseases • Hepatitis B (HBV) • Transmission • Blood to Blood • Sexual Contact • West Nile, Lyme, HIV, Flu & SARS • Viruses that move from animals to humans • Prevention • WASH YOUR HANDS!!! • Vaccinations • Education • Knowing the history of one’s partners

16. Risk and Infectious Diseases • One major pathway of risk is contamination of food and water • Inadequate hygiene • Inferior sewage treatment

17. Control of Infectious Disease • Genome sequencing of the Anopheles mosquito • Bed nets • Change in land use practices: wetland development • New effective antimalarial drugs

18. Chemical Hazards • Toxic Chemicals • Carcinogens – Cause Cancer • 74 chemicals are known to be carcinogenic • Environmental carcinogens initiate mutations in DNA; several mutations lead to a malignancy • Mutagens – Cause Mutations • Teratogens – Cause Birth Defects

19. Chemical Hazards • Result of industrialization • Exposure through ingestion, inhalation, absorption through skin • May be direct use or accidental • Many chemicals are toxic at low levels • PCBs • Mercury • Bisphenol A

20. PCBs • Class of chlorine-containing compounds • Very stable • Nonflammable • Break down slowly in the environment • Travel long distances in the air • Fat soluble • Biomagnification • Food chains and webs • Banned, but found everywhere

21. Mercury & Minamata Disease • Hg: teratogen and potent neurotoxin • Once airborne, persistent and not degradable • 1/3 from natural sources • 2/3 from human activities • Enters the food chain: biomagnification • How are humans exposed? • Inhalation: vaporized Hg or particulates of inorganic salts • Eating fish with high levels of methylmercury (Minamata Disease) • Effects of Hg on humans • Neuroligical • ataxia, numbness, weakness, vision, hearing, speech • Insanity, paralysis, coma, death • Who is most at risk? • Children • Pregnant women and fetuses

22. Chemical Hazards • Other Chemicals • Suppress the Immune System • Interfere with the Nervous System • Interrupt the Endocrine System – Hormonally Active Agents (phthalates) • Gender Benders • Thyroid Disrupters • Cancer • Obesity

23. Bisphenol A (BpA) • Estrogen mimic • Found in many common products made of plastic • Laboratory findings indicate heated plastic releases compounds into food and water • Effects on human health • Females – excessive hair, early menstruation & menopause, cancer • Males – breasts, shrunken testes, cancer • OBESITY • Should it be banned?

24. Environmental Health • Factors contributing to the environmental health of a nation include: • Education • Nutrition • Commitment from government • More equitable distribution of wealth

25. Toxic Risk Pathways • Categories of impact of pollutants • Chronic: effect takes place over a period of years • Acute: life-threatening reaction within a period of hours or days • Carcinogenic: pollutants initiate cellular change leading to cancer

26. Pathways of Risk • The risk of being poor • The cultural risk of tobacco use • Risk and infectious diseases • Toxic risk pathways

27. The Risk of Being Poor • One major pathway for hazards is poverty • No money for health insurance • Higher probability of exposure to environmental hazards

28. The 10 Leading Global Risk Factors Fig. 15-9 here

29. Example: Indoor Air Pollution • Developed Countries • Hazardous fumes from home products • Well-insulated buildings • Long exposure to indoor air • Developing Countries • Results from burning biofuels (wood, dung) inside homes • Acute respiratory infections in children • Chronic lung diseases • Lung cancer • Birth-related problems

30. Cultural Hazards • Consequence of choice • Risky behavior • To what cultural hazards do students commonly subject themselves? • Driving • Drugs, Alcohol, and Tobacco • Poor food Choices

31. Deaths from Various Cultural Hazards

32. The Cultural Risk of Tobacco Use

33. Risk Assessment • Environmental risk assessment by the EPA • Public-health risk assessment • Risk management • Risk perception

34. Definition of Risk Assessment • The process of evaluating the risks associated with a particular hazard before taking some action in which the particular hazard is present

35. Environmental Risk Assessment by the EPA • Toxicology • Hazard assessment (What chemicals cause cancer?) • Dose-response assessment (How much?) • Exposure assessment (Who? How long?) • Age • Genetics • Solubility & Persistence of Chemicals • Biomagnification • Multiple Chemical Sensitivity (MCS) • Risk characterization (How many will die?)

36. Kids and Chemicals – Analysis of umbilical cord blood • Infants and children more susceptible to the toxic effects of chemicals than adults • Eat, drink water, and breathe more per unit of body weight than adults • Put their fingers in their mouths • Less well-developed immune systems and body detoxification processes

37. Estimating Toxicity – Use of Animals and Nonanimals • Dose-response curve: median lethal dose (LD50) • Non-threshold dose-response model • Threshold dose-response model • Can the data be extrapolated to humans? • Are there more humane methods? • Computer simulations • Tissue cultures • Chicken egg membranes

38. The Results of Toxicological Studies - Regulation of Smoking • Warning labels • Smoke-free zones in public places • FDA regulations • Lawsuits against the tobacco industry • Taxes • Education

39. Public-Health Risk Assessment • Potential global impact • High likelihood of causality • Modifiability • Availability of data

40. Risk Management • Usually involves: • Cost–benefit analysis • Risk–benefit analysis • Public preferences

41. Risk Perception: Hazard vs. Outrage • Hazard: expresses primarily a concern for fatalities only

42. Risk Perception: Hazard vs. Outrage • Outrage includes: • Lack of familiarity with technology • Extent to which the risk is voluntary • Public impressions of hazards • Overselling safety • Morality • Control • Fairness

43. Risk Assessment/Management • Some suggest we use distributive justice in making decisions about risk • Ethical process of making certain that everyone receives proper consideration • Should reduce environmental racism/injustice

44. Risk Assessment/Management • Not a perfect system • Precautionary principle • Lack of certainty should not be used as a reason for preventing environmental degradation/hazards • Those introducing a new chemical or new technology would have to follow new strategies • A new product is considered harmful until it can be proved to be safe • Existing chemicals and technologies that appear to cause significant harm must be removed • 2000: global treaty to ban or phase out the dirty dozen (POPs)