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Chapter 14: Risk, Human Health, and Toxicology

Chapter 14: Risk, Human Health, and Toxicology. By Emmaline Meill, Jae Young Park, and Anya Lukianchikov. Case Study: Cigarette Smoking. Cigarette smoking is the world’s most preventable cause of suffering and premature death among adults. 1950-2005, it has killed 85 million people.

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Chapter 14: Risk, Human Health, and Toxicology

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  1. Chapter 14: Risk, Human Health, and Toxicology • By Emmaline Meill, Jae Young Park, and Anya Lukianchikov

  2. Case Study: Cigarette Smoking • Cigarette smoking is the world’s most preventable cause of suffering and premature death among adults. • 1950-2005, it has killed 85 million people. • Kills 440,000 Americans prematurely each year.

  3. Case Study - Continued • Cigarette smoking causes numerous other diseases: • Heart Disease • Cancer • Emphysema • Bronchitis • Stroke • 2004 study found that cigarette smokers die on average 10 years earlier than non-smokers.

  4. What’s in a cigarette?

  5. Case Study - Continued • Suggested reforms: • Federal tax on cigarette packets • Banning cigarette advertising • Banning tobacco products to anyone younger than 21 • Education programs

  6. 14-1 Risks and Hazards • Risk is the possibility of causing harm from a hazard that can cause injury, disease, death, economic loss, or environmental damage. • Risk Assessment is the estimation of how much harm a hazard can cause to human health. • Risk management is deciding whether or how to reduce a risk to a certain level and at what cost.

  7. Risks and Hazards - Continued • Four types of hazards • Cultural • Biological • Chemical • Physical

  8. Boo, the Bubonic Plague (Yersinia pestis) bacterium 14-2 Biological Hazards: Disease in Developed & Developing Countries Necors, the Necrotizing Phaciatis bacterium Ebola, the Ebola Virus particle

  9. Science: Diseases • Nontransmissible • Transmissible/Infectious • WHO: World Health Organization Good news: falling death rates Bad news: increased resistance

  10. Growing Germ Resistance to Antibiotics: Contributing Factors • Rapid bacteria reproduction • Modern high-speed travel/trade • Overuse • Underuse MRSA is a big one

  11. Case Study: Growing Threat of TB • 9 million/yr infected; 1.7 mil/yr killed • Factors: • Lack of screening/control plans • ↑ Resistance • Pop. growth, urbanization • AIDS

  12. Viral Diseases • Biggest killers: HIV, Flu, Hep B • Flu – 40,000 dead/yr in US, bad epidemics • Media focus on more “exotic” diseases Influenza is much worse than I am!

  13. Case Study: HIV/AIDS • Most serious & rapidly growing health threat • Long incubation period, $$$ drugs • Effects in Africa: • ↓ life expectancy of 700 mil by 15 yrs • Productive ppl. killed, less productivity • Age structure • WHO global strategy

  14. Case Study: Malaria • 1/5 ppl. at risk • Malaria Cycle • Best thing now: Prevention • Prevent mosquito growth • Zn & Vit. A Suppliments It’s got quite the history, like me!

  15. ↓ Incidence of Infectious Diseases • Death rates falling – allID’s overall • Easily preventable ones now treated • Bad news: little funding for LDC IDs • Kill more than other IDs combined Diseases that are easily preventable are now being treated more in LDCs, reducing death rates.

  16. Bioterrorism • Biological WMDs since WWII • Deadlier strains; new types of pathogens • Easy to spread • Combatting I might be one of them!

  17. 14-3 Chemical Biohazards • Toxic Chemical • Hazardous Chemical • Agent types • Mutagen: DNA • Teratogen: birth defects • Carcinogen: cancer

  18. Effect of Chemicals on Bodily Systems • Disrupts • Immune: weaken • Nervous: disrupt/harm – kill cells • Neurotoxins • Endocrine: disrupt effect of nat. hormones • Hormonally Active Agents (HAAs)

  19. 14-4 — Toxicology: Assessing Chemical Hazards • Toxicity depends on several factors • Dosage • Frequency • Person exposed • Effectiveness of detoxification systems • Genetic makeup • Multiple chemical sensitivity • Factors affecting severity of a toxin • Persistence • Solubility • Bioaccumulation • Biomagnification • Antagonistic/Synergistic interaction

  20. Assessing Chemical Hazards (cont’d) • Responses to toxin • Acute effects • Chronic effects • Body functions • Kidney/liver • Enzymes • Cell reproduction

  21. Effects of Trace Levels of Toxic Chemicals • Trace amounts debate • Misconceptions • Increasingly detected amounts  good news • Natural vs. Synthetic chemicals Nightshade

  22. Estimating the Toxicity of a Chemical • Poison/toxin’s lethal doses • Animal tests (LD50=50%) • Wide variations between two extremes (completely lethal vs. barely)

  23. Using Case Reports and Epidemiological Studies to Estimate Toxicity • Case reports = not precise, gives clues & hints • Epidemiological studies — experimental vs. control groups • Limiting factors • Few people • Linking back to exact, specific chemicals • Can’t predict/evaluate future hazards

  24. Using Laboratory Experiments to Estimate Toxicity • Animal testing • Expensive, takes long • Animal welfare groups • Computer simulations • Tissue cultures • Chicken egg membranes • Dose-response curve • Nonthreshold dose-response model • Threshold dose-response model • Difficulties • Valid? • Exposure to many chemicals  chemical interactions • Economically/Scientifically impossible

  25. Protecting Children from Toxic Chemicals • Children more susceptible • Consumption levels • Environment • Body not developed • 2003 US EPA — assume 10x more exposure ~boyfriend~

  26. Why Do We Know So Little about the Harmful Effects of Chemicals? • Faulty/limited methods • 10% of 80,000 chemicals studied, 2% adequately tested • Few regulations • “innocent until proven guilty” • Lack of funds/workforce/etc.

  27. Pollution Prevention and the Precautionary Principle • Pollution prevention based on precautionary principle • 2004 global treaty banning Persistent Organic Pollutants (POP) aka “dirty dozen” • DDT, 8 persistent pesticides, PCBs, dioxins, furans • Businesses vs. supporters  technology debate

  28. 14-5 Risk Analysis • Today, the greatest risk is poverty • Risk analysis involves: • Identifying hazards • Ranking risks • Making decisions about reducing risks • Informing the public about risks

  29. Perceiving Risks • Many people shrug off the high-risk chances of death or injury from voluntary activities they enjoy. • Factors can give people a distorted sense of risk

  30. Best Ways to Reduce Health Risks • Avoid smoking • Lose excess weight • Healthy diet • Exercise regularly • Don’t drink alcohol • Avoid excessive sunlight • Practice safe sex

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