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Do Now

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  1. Do Now • President Obama mentioned several times that we need to “invest” in things like electric cars. • Is this helping the problem of diversifying our energy needs and reducing CO2 gases. • Thoughts?

  2. Homework • Due today in class: • Finish Reading chapter 14 - should already be completed. • Vocab Quiz tomorrow • Begin to review – The Final Exam will consist of Chapters 8 - 14

  3. BPa • Bisphenol A binds to estrogen receptors • Phthalates in plastics disrupt hormones • Toys, perfumes, makeup • Birth defects, cancer, reproductive effects

  4. Toxins and chemicals route of travel

  5. Boards • Explain the term below. • Pesticide drift

  6. Toxins and chemicals route of travel • Chemicals can travel by air • Their effects can occur far from the site of use • Pesticide drift = airborne transport of pesticides • Synthetic chemicals are found globally

  7. Boards • Breakdown products – explain this term

  8. Breakdown of toxins and chemicals • Toxins can degrade quickly and become harmless • Or they may remain unaltered and persist for decades • Rates of degradation depend on the substance, temperature, moisture, and sun exposure • Breakdown products = simpler products that toxicants degrade into • May be more or less harmful than the original substance • DDT degrades into DDE, which is also highly persistent and toxic

  9. Increase in toxins • Toxicants in the body can be excreted, degraded, or stored • Fat-soluble toxicants are stored in fatty tissues • Bioaccumulation = toxicants build up in animal tissues • Biomagnification = concentrations of toxicants become magnified • Near extinction of peregrine falcons and bald eagles

  10. How do they test chemicals • Animals are used as test subjects • Mammals share evolutionary history • Substances that harm rats and mice are likely to harm us • Dose-response analysis = measures the effect a toxicant produces or the number of animals affected • Dose = amount of substance the test animal receives • Response = the type or magnitude of negative effects

  11. Chemical harm • LD50/ED50= the amount of toxicant required to kill (affect) 50% of the subjects • A high number indicates low toxicity • Threshold dose = the level where certain responses occur • Theo Colburn’s Our Stolen Future (1996) describes how synthetic chemicals may be changing hormones

  12. Exposure • Acute exposure vs. Chronic exposure • Acute = high exposure to a hazard for short periods of time and Chronic exposure = low exposure for long periods of time • Risk = the probability that some harmful outcome will result from a given action, event, or substance

  13. Philosophy of harm • There are two basic principles surround harm / safety: • Innocent-until-proven-guilty approach or Precautionary principle • Explain the difference • Role of the government: • The FDA: monitors food, food additives, cosmetics, drugs, medical devices • The EPA: regulates pesticides and chemicals not covered by other laws

  14. Cracking down on Toxins • The EU’s REACH program (Registration, Evaluation, Authorization, and Restriction of Chemicals) shifts the burden of proof for safety to industry • Stockholm Convention on Persistent Organic Pollutants (POPs) POPs = toxic, persistent chemicals. Enacted in 2004 and ratified by over 150 nations. • Stockholm Convention sets guidelines for phasing out these chemicals