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  1. TOXIC BOTTLES?On the trail of chemicals in our everyday lives CHAPTER 3 INFORMATION LITERACY

  2. 3 TOXIC BOTTLESOn the trail of chemicals in our everyday lives Learning Outcomes • At the end of this chapter, you should know: • The importance of information literacy and ways logic can be distorted • How to evaluate the quality of information • How risk assessment helps determine safe exposure levels to environmental toxins

  3. 3 TOXIC BOTTLESOn the trail of chemicals in our everyday lives Information contributing to our knowledge about nature is being continually revised as we learn more about toxins and biochemical processes. Not all sources of information are equally valid or trustworthy! Main Concept

  4. 3 TOXIC BOTTLESOn the trail of chemicals in our everyday lives Case: BisphenolA (BPA) and health effects BPA is a synthetic chemical from the 1940s used to line metal food cans and in the production of plastic bottles—including baby bottles. Studies began showing an association between BPA and serious medical conditions. BPA wasbanned in Canada and the U.K. Plastics industry challenged the science claiming BPA was safe. Without government protection, what should we do?

  5. 3 We live in an environment full of toxins Synthetic toxins – Many and persistent; don’t degrade over time. Natural toxins – Natural doesn’t always mean safe! Consider arsenic in groundwater. Regulation becomes a challenge – How much is safe?

  6. 3 We live in an environment full of toxins Early insight came from Rachel Carson in her 1962 book Silent Spring, in which she highlighted a significant die-off following only two decades of extensive use of DDT and other herbicides and pesticides. DDT was doing what it supposed to do—kill pests, including the mosquitoes responsible for malaria. But…

  7. 3 We live in an environment full of toxins • Carson identified three specific concerns that had not yet been addressed: • Some chemicals have large effects in small doses. • Certain stages of human development are especially vulnerable to effects. • Mixtures of different chemicals can have unexpected impacts. • One result of the book was a movement toward stricter regulations for chemical pesticides and a U.S. ban on DDT.

  8. 3 Regulation happens even in the face of change TERMS TO KNOW: Toxins Persistent chemicals Risk assessment Precautionary principle Risk Assessment The goal of risk assessment is to weigh the costs and benefits associated with any specific chemical. In reality, it is impossible to fully understand and assess all potential interactions among the many chemicals to which we are exposed on a daily basis. Reality includes practicality, economic forces, and the basic need for the chemical.

  9. 3 Regulation happens even in the face of change Risk Assessment Food and Drug Administration (FDA) – Authority that regulates and bans harmful chemicals In uncertainty, “better safe than sorry,” known as the precautionary principle until exposure limits are determined, versus “Innocent until proven guilty,” using recalls rather than prevention. This leaves the burden of proof on the public. How do we weigh information from which we make our decisions? TERMS TO KNOW: Toxins Persistent chemicals Risk assessment Precautionary principle

  10. 3 Scientific information can generally be divided into two types: primary and secondary Primary sources include new and original information from research—usually rigorously reviewed by peers in the scientific community for design, data, and analysis.

  11. 3 Scientific information can generally be divided into two types: primary and secondary Secondary sources include interpretation of primary sources and lack of peer review. This is what you read in the popular press.

  12. 3 Scientific information can generally be divided into two types: primary and secondary Tertiary sources interpret information from secondary sources, often over-simplifying, while providing additional commentary and stimulating debate over an issue.

  13. 3 What are dangers presented by toxins and how do we determine safe exposure levels? Case: BisphenolA (BPA) and health effects TERMS TO KNOW: Information literacy Primary sources Peer review Secondary sources Tertiary sources Sampling: 2000 urine samples 90% positive for BPA Average concentration 2.6 ppb Top 5% almost 16 ppb – Beyond the amount found to cause harm in rodents Concentration decreasing with age indicates BPA leaching from food containers into bodies. Greater exposure among younger people as more products used BPA in packaging Results are in, but does that mean BPA is dangerous in humans?

  14. 3 What are dangers presented by toxins and how do we determine safe exposure levels? • Evaluating safety • How persistent is the substance? • Low persistence - Break down quickly with sunlight • High persistence - Long time to break down and potential environmental impact long after initial release

  15. 3 What are dangers presented by toxins and how do we determine safe exposure levels? • Evaluating safety • How soluble is the substance? • Water and other liquids: • May be safer for humans—excrete in urine • Still potential toxic at high doses or continual low dose • High impact on aquatic organisms—easy uptake • Fat-soluble: • Cross cell membrane in humans and hard to eliminate • Some break down by liver • Storage and accumulation in fatty tissue

  16. 3 What are dangers presented by toxins and how do we determine safe exposure levels? Bioaccumulation – Fat-soluble substances build up in tissues of an organism over time. Biomagnification – Higher on the food chain and able to consume the entire lifetime of toxins in their prey Tuna and swordfish are large predators high on the ocean food chain. They accumulate and magnify mercury, PCBs, and DDT.

  17. 3 What are dangers presented by toxins and how do we determine safe exposure levels? Biomagnification – Higher on the food chain and able to consume the entire lifetime of toxins in their prey Tuna and wwordfish are large predators high on the ocean food chain. They accumulate and magnify mercury, PCBs, and DDT. TERMS TO KNOW: Bioaccumulation Biomagnification Epidemiologist Toxicologists In vitro study In vivo study Persistence Solubility

  18. 3 What are dangers presented by toxins and how do we determine safe exposure levels? Epidemiologists - Determining cause and effect Look for health problem in a specific population and work backwards for cause or look at group with exposure and identify common health problems BPA case – Looked at individuals with BPA in urine and found correlation between BPA concentration and cardiovascular disease.

  19. 3 What are dangers presented by toxins and how do we determine safe exposure levels? Toxicology - Determining properties of toxins and their effects on cells and tissues Testing on animals—in vivo (“in body”) Testing cells in petri dishes—in vitro (“in glass”) BPA case – Looked at individuals with BPA in urine and found correlation between BPA concentration and cardiovascular disease.

  20. 3 What are dangers presented by toxins and how do we determine safe exposure levels? Testing on animals – in vivo (“in body”)

  21. 3 What are dangers presented by toxins and how do we determine safe exposure levels?

  22. 3 What are dangers presented by toxins and how do we determine safe exposure levels?

  23. 3 What are dangers presented by toxins and how do we determine safe exposure levels?

  24. 3 What are dangers presented by toxins and how do we determine safe exposure levels? In vivo and in vitro studies both show negative effects of BPA—one on prostate size, the other on cell survival.

  25. 3 What are dangers presented by toxins and how do we determine safe exposure levels? Effects of variables on toxicity Variables – Genetics, age, general health status Lang study – Urine BPA levels of 1455 subjects Statistical adjustment for specific variables Diagnosis of seven health conditions compared to BPA levels

  26. 3 What are dangers presented by toxins and how do we determine safe exposure levels? High overlap between high BPA in urine of subjects with and without stroke and liver disease—BPA not implicated Those with higher BPA levels showed significantly higher incidence of diabetes and CVD. Almost no overlap between those with and without diabetes and CVD beyond BPA ppb 4-5

  27. 3 What are dangers presented by toxins and how do we determine safe exposure levels? High overlap between high BPA in urine of subjects with and without stroke and liver disease—BPA not implicated Those with higher BPA levels showed significantly higher incidence of diabetes and CVD. Almost no overlap between those with and without diabetes and CVD beyond BPA ppb 4-5

  28. 3 Endocrine disruptors cause big problems at small doses Determining toxicity Effects of variables on toxicity Variables – Genetics, age, general health status Individual factors – Some toxins are more of a problem in the very young or the very old, or those who are ill. Genetic factors may make a person more or less vulnerable to the toxin. Exposure – Whether the toxin is inhaled, ingested, or contacts the skin makes a difference in toxicity. Frequency of exposure also matters.

  29. 3 Endocrine disruptors cause big problems at small doses Additive effects – Other chemicals may increase the effect of the toxin. Antagonistic effects – Other chemicals reduce or cancel the toxin’s effects. Synergistic effects – Chemicals increase the effects of the toxin, even beyond expectations. TERMS TO KNOW: Endocrine disruptors Hormone Receptor

  30. 3 Endocrine disruptors cause big problems at small doses Additive effects –Ttherchemicals may increase the effect of the toxin. Antagonistic effects – Other chemicals reduce or cancel the toxin’s effects. Synergistic effects – Chemicals increase the effects of the toxin, even beyond expectations. TERMS TO KNOW: Endocrine disruptors Hormone Receptor

  31. 3 Endocrine disruptors cause big problems at small doses Additive effects – Other chemicals may increase the effect of the toxin. Antagonistic effects – Other chemicals reduce or cancel the toxin’s effects. Synergistic effects – Chemicals increase the effects of the toxin, even beyond expectations. TERMS TO KNOW: Endocrine disruptors Hormone Receptor

  32. 3 Endocrine disruptors cause big problems at small doses Determining toxicity Effects of variables on toxicity Variables – Genetics, age, general health status Additive effects – Other chemicals may increase the effect of the toxin. Antagonistic effects – Other chemicals reduce or cancel the toxin’s effects. Synergistic effects – Chemicals increase the effects of the toxin, even beyond expectations. What does the saying mean? “The dose makes the poison.” TERMS TO KNOW: Additive effects Antagonistic effects Synergistic effects

  33. 3 Endocrine disruptors cause big problems at small doses • Endocrine disrupters interfere with the endocrine system. • They mimic a hormone or prevent a hormone from having an effect. • BPA is an estrogen mimic—it binds to estrogen receptors and triggers the effects associated with estrogen: • Feminization of males • Lowered sperm counts • Production of egg proteins • Endocrine disrupters don’t follow “the dose makes the poison.” • The can have one set of effects at a low dose and no effect or different effects at higher doses. • How can we determine the • effect of a dose? TERMS TO KNOW: Dosed-response curve LD50 (lethal dose 50%)

  34. 3 Endocrine disruptors cause big problems at small doses LD50 is lethal dose for 50% of the population TERMS TO KNOW: Dosed-response curve LD50 (lethal dose 50%)

  35. 3 Endocrine disruptors cause big problems at small doses Lower LD50 more toxic TERMS TO KNOW: Dosed-response curve LD50 (lethal dose 50%)

  36. 3 Endocrine disruptors cause big problems at small doses Determine “safe dose” based on finding threshold dose—dose where effects are first seen—and continue testing effects at higher doses or starting at high doses and reducing dosage until no effects are seen. For endocrine disruptors, high- and low-dose effects must be assessed separately.

  37. 3 Endocrine disruptors cause big problems at small doses History for another endocrine disrupter: Diethylstilbesterol (DES) used to prevent premature labor—research indicated an exact response for humans and for a strain of rat. Using this same strain of rat, BPA showed increased postnatal growth, early onset of sexual maturation in females, decreased testosterone and increased prostrate size, altered immune function, and increased embryo mortality.

  38. 3 Endocrine disruptors cause big problems at small doses History for another endocrine disrupter: Diethylstilbesterol (DES) used to prevent premature labor—research indicated an exact response for humans and for a strain of rat . Using this same strain of rat, BPA showed increased postnatal growth, early onset of sexual maturation in females, decreased testosterone and increased prostrate size, altered immune function, and increased embryo mortality.

  39. 3 Endocrine disruptors cause big problems at small doses How hormones work Steroid hormone enters cells and binds to receptor

  40. 3 Endocrine disruptors cause big problems at small doses How hormones work Steroid hormone enters cells and binds to receptor Hormone receptor complex binds to DNA in cell nucleus

  41. 3 Endocrine disruptors cause big problems at small doses How hormones work Steroid hormone enters cells and binds to receptor Hormone receptor complex binds to DNA in cell nucleus Binding activates gene which directs protein production

  42. 3 Endocrine disruptors cause big problems at small doses How hormones work How hormones work Steroid hormone enters cells and binds to receptor Hormone receptor complex binds to DNA in cell nucleus Binding activates gene which directs protein production New protein made Protein changes cellular activity

  43. 3 Endocrine disruptors cause big problems at small doses Based on effect of low-dose BPA on rodents, and the history of endocrine disruptors like DES, what might be the potential risks to pregnant mothers, developing fetuses, and young children? BPA broken down in mother and excreted in urine? NO Protection of fetus by placenta? NO BPA in both maternal and fetal blood at levels high enough to cause harm.

  44. 3 Endocrine disruptors cause big problems at small doses Based on effect of low dose BPA on rodents, and the history of endocrine disruptors like DES, what might be the potential risks to pregnant mothers, developing fetuses, and young children? BPA broken down in mother and excreted in urine? NO Protection of fetus by placenta? NO BPA in both maternal and fetal blood at levels high enough to cause harm

  45. 3 Critical thinking skills give us the tools to uncover logical fallacies in arguments or claims TERMS TO KNOW: Critical thinking Logical fallacies What about regulation for BPA?

  46. 3 Critical thinking skills give us the tools to uncover logical fallacies in arguments or claims TERMS TO KNOW: Critical thinking Logical fallacies What about regulation for BPA?

  47. 3 Critical thinking skills give us the tools to uncover logical fallacies in arguments or claims TERMS TO KNOW: Critical thinking Logical fallacies What about regulation for BPA?

  48. 3 Critical thinking skills give us the tools to uncover logical fallacies in arguments or claims TERMS TO KNOW: Critical thinking Logical fallacies What about regulation for BPA?

  49. 3 PERSONAL CHOICES THAT HELP www.ewg.org/skindeep

  50. 3 UNDERSTANDING THE ISSUE