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February 26, 2014 Chapter 18: Environmental Hazards and Human Health February 26, 2014 Types of Hazards 1. Biological 2. Chemical 3. Physical 4. Cultural February 26, 2014 Biological Hazards February 26, 2014 Bacterial infections: • TB • Diarrheal diseases (Cholera) • Antibiotic resistance February 26, 2014 Viral Diseases • Influenza • HIV • Hepatitis • Measles • Diarrheal diseases (Rotavirus) February 26, 2014 Protozoa • Malaria • Diarrheal disease (Giardia) February 26, 2014 Ecological Medicine *track infectious disease that potentially cross from animals to humans • HIV-bushmeat • Nipah virus-clearing forests + pig farms • Malaria-clearing forest increase range of mosquitos • Lyme disease-suburbs • E.coli-factory farming February 26, 2014 Chemical hazards • Mutagens • Teratogens • Carcinogens • Disrupts: > immune system > nervous system (neurotoxin) > endocrine system (hormonally active agents (HAA) – Mimic and blockers – BPA – Phthalates February 26, 2014 Chemical Hazards • 7 factors that affect extent of harm: > dose > genetics > solubility > persistence > bioaccumulation > biomagnification > chemical interactions (antagonistic or synergistic) February 26, 2014 Toxicity Assay: LD50 = median lethal dose • Relative indicator of how toxic or how dangerous chemical is • Dose that kills 50% of animals in a test population within certain period of time (18-days). > Usually measured in amount/kg of body weight – "amount" = g, mg, ng, etc depending on substance What is more toxic? Something with LD50 0f 50 or 5? February 26, 2014 Toxicity Assay: LC50 = median lethal concentration • Relative indicator of how toxic or how dangerous chemical is • Concentration not dose > Sometimes difficult to measure exposure by dose so use concentration instead > ex: Fish in water--can't make fish ingest a certain amount of toxin. February 26, 2014 Bioassay done with live animals What animals would you use? Ethical? February 26, 2014 Brine Shrimp Toxicity Assay -Find out lethal concentration of common household cleaners. February 26, 2014