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Human Health and Environmental Toxicology Chapter 7
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Human Health Overall human health best assessed by: 1) Life expectancy (years) 2) Infant mortality (# deaths up to age one per 1,000 live births)
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Life Expectancy / Infant Mortality Selected countries, 2004 data Life Expectancy (years) Infant Mortality (# deaths up to age one per 1,000 live births) Japan Source: U.S. Census Bureau, International Database 81.23.3 Switzerland80.44.4 Sweden80.42.8 Mozambique40.3130.8 Zimbabwe36.760.7 Angola36.6191.2
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Health Issues in Highly Developed Countries Leading causes of death in US: Cardiovascular diseases, cancer, & chronic obstructive pulmonary disease Linked to... Obesity
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Health Issues in Developing Nations Malnutrition, unsafe water, and poor sanitation Leads to... Numerous infectious diseases Compounded by poor healthcare, leads to... Lowered life expectancy
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Emerging v. Reemerging Diseases Emerging – Not previously observed within humans: AIDS, Lyme disease, West Nile virus Reemerging – Existed previously, becoming more common again: Tuberculosis, Yellow fever, Malaria
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Environmental Pollution & Disease
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Persistence Degradation of synthetic pesticides is slow. Many remain in soil / water for years.
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Bioaccumulation Natural substances commonly recycle in living organisms. Intake = Output (no long term accumulation) Synthetic substances typically not metabolized. Intake, with little output = accumulation (typically in fat)
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Biomagnification
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Example: Effect of DDT on bald eagles
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Endocrine Disruptors Chemicals that alter hormone production. Ex: PCBs, dioxins, lead, mercury, DDT Hormones have their affect at low doses. Endocrine disruptors act similarly.
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Endocrine Disruptors Example: American alligators and DDT spill
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Determining Health Effects of Environmental Pollution Toxicant – Chemical that induces adverse response at a certain dose. Toxicity of a chemical is assessed by determining its LD 50 (dose at which 50% of test subjects die due to exposure)
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Determining Health Effects of Environmental Pollution Lethal Dose-50% (LD 50 )
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Determining Health Effects of Environmental Pollution Effective Dose-50% (ED 50 ) – Dose that induces 50% of test subjects to have some type of effect Dose response curve –
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Determining Health Effects of Environmental Pollution Children and chemical exposure
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Determining Health Effects of Environmental Pollution Identifying Cancer-Causing Substances Carcinogen – Environmental agent known to induce cancer. Chemicals commonly tested with rats but, is the dose equivalent? Can you extrapolate the results to humans?
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Determining Health Effects of Environmental Pollution Chemical Mixtures Most studies examine effect of single chemical exposure. What happens when exposed to multiple chemicals? Additive effect? Synergistic effect? Antagonistic effect?
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Ecotoxicology Dilution paradigm – “the solution to pollution is dilution” Boomerang paradigm – “what you throw away can come back and hurt you”
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Ecotoxicology Case in Point: The Ocean and Human Health
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Decision Making and Uncertainty Risks:
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Decision Making and Uncertainty Risk assessment: Low High
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Decision Making and Uncertainty Risk assessment:
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Decision Making and Uncertainty Ecological risk assessment: Extends steps of risk assessment to the impact on all plants, animals, and other organisms in an area.
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Decision Making and Uncertainty Ecological risk assessment example: Dams on Snake River
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Decision Making and Uncertainty Cost-Benefit Analyses Cost Benefit
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