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Human Health and Environmental Toxicology
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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
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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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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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Decision Making and Uncertainty Risk assessment: Low High
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Representative Cellular Targets for Toxic Action 11
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Three Stages in Carcinogenesis StageNormal cellCarcinogenic agent Initiation Genotoxic initiator Co-carcinogen Initiated cell Promotion Promoter Immunosuppressor Cancer Hormones Dietary compounds Other ProgressionInvasion Metastasis {{{{ {
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Metabolic Activation of Benzo(a)pyrene
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2,3,7,8-Tetrachlorodibenzo(p)dioxin
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Lock and Key Model for Toxic Action Disrupt normal steroid action and may influence the development of endometriosis. A by-product of manufacture and combustion of chlorinated phenols and is considered by some to be one of the most toxic substances ever released into the environment.
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Toxicological/Ecological Relevance and Time Scale of Toxic Response for Levels of Biological Organization (McGarthy and Shugart, 1989) 16
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Idealized Plot of Dose-Response Relationship (Health 1987)
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Biomagnification of Pesticides in Aquatic Food Chains (Connell 1990)
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Possible Movement and Fate of a Contaminant after Absorption into the Bloodstream of a Fish (Health 1987) 19
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