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Chapter 10: Toxicology

Chapter 10: Toxicology . The study of the effects of poisonous chemicals on organisms and the environment. Paracelcus—1520’s. The dose makes the poison. Everything is poisonous to living organisms, if the dose is high enough Oxygen Water Salt Sugar.

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Chapter 10: Toxicology

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  1. Chapter 10: Toxicology The study of the effects of poisonous chemicals on organisms and the environment.

  2. Paracelcus—1520’s • The dose makes the poison. • Everything is poisonous to living organisms, if the dose is high enough • Oxygen • Water • Salt • Sugar

  3. Therefore, with life comes poisons…toxicology is not new. • Hemlock tea killed Socrates • Poison darts are used in hunting • Mercury was used in the felting process creating “Mad Hatters”

  4. But with the Chemical Revolution of the 1920’s came… • Synthetic chemicals: • Plastics • Pesticides • Flavors • Dyes • Smells • Paints

  5. 1950’s … • People started to notice problems with people and the environment.

  6. Chemicals effect organisms individually or synergistically: • Carcinogen---causes cancer • Mutagen---causes mutations in DNA • Teratogen---causes birth defects • Allergens—over-stimulates the immune system • Neurotoxins---assaults the nervous system (brain, spine, nerve cells) • And….

  7. 6. Endocrine Disruptors • Endocrine system is the systems that controls the chemical messengers in the body (hormones) • “Our Stolen Future” (Colbern, Meyers, Dumanoski—1996) • Current Issue: Bisphenol-A (BPA) in plastics

  8. Toxicology Studies • We use other organism to study effects of poisons because using humans in un-ethical • Many chemicals are broken down in the body and quantified by “half-life” • Classify effects: a. LD50 = 50% organisms are dead b. ED50 = 50% organisms are affected c. Threshold Dose =dose that causes effect

  9. LD50 Threshold

  10. Harm can manifest from different exposure times: • Chronic = long term exposure • Using Tobacco • Acute = immediate exposure • Drinking Gasoline

  11. Human Health and Risk Management • Risk is measured in probability • Perception does not always match reality • For instance: • Are you more afraid of Antibiotics or Spiders? • Snakes or Cars? • Cars or Planes?

  12. Reality does not always match perception: • Spider deaths—1:30 million • Antibiotics—1:90,000 • Snake deaths—1: 1 million • Car Deaths —1:84 • Plane Crash—1:9 million • Shuttle Launch—1: 100 • Alcohol Poisoning—1: 10,000

  13. Take-home: • Information and data is critical to overcoming irrational beliefs and fears. • Information and data is critical to efficient risk management.

  14. The Future of Environmental Toxicology • Toxic issues: • Location • Poverty and Environmental Justice • Life of chemicals in the environment • There is no hiding from synthetic chemicals

  15. Future Issues: Diseases • A. Infectious diseases account for ½ of all deaths in the developing world because of lack of hygiene and medicine. These could be prevented. • B. Types of diseases: • Viruses • InfluenzaPneumonia = 3.2 mdy • HIV/AIDs = 3 mdy • Hepatitis B = 1 mdy

  16. Disease Types Continued • Bacteria • Tuberculosis (TB) = 1.7 mdy • Cholera = 1.9 mdy • Plague (90-100% mortality) • Increasing problems with antibiotic resistance

  17. Diseases Continued: Cancer • Cancer is uncontrolled cell division. • Cancer kills 1:7 people in the USA • Cancer has many causes: • Environmental, Natural, and Viral

  18. Diseases: Other • Parasites • Malaria = 1 mdy • Tapeworms, liver flukes, etc • Giardia/ “Beaver Fever” • Protozoa passed through contaminated water • Respiratory disorders due to pollution

  19. Global Climate Change Affects Diseases • Tropical diseases like malaria are spreading to areas that would have not had malaria due to changing climates

  20. Solutions: • Decrease Poverty • Increase research of diseases • Education • Immunization (Small Pox/ Polio) • Reduce antibiotic use/ misuse • Improve drinking water quality • Collect and treat sewage • Decrease malnutrition • Others?

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