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Chapter 14 Environmental Health, Pollution & Toxicology Categories of Pollutants • Biological Hazards – Viral: HIV, Hantavirus, Dengue Fever, Ebola, Smallpox, chicken pox The stylets (needle-like structures) and proboscis (elongated mouth) of an Aedes aegypti feeding. Dengue viruses are transmitted during the feeding process. Biological Hazards – Bacterial: Anthrax, Lyme disease, Salmonella – Parasitic: Legionellosis (Legionnaires’ Disease), Giardiasis, Malaria, Cryptosporidosis • Vector: insect or organism that can transport and transmit infectious agent • Reservoir: organism that carries infectious agent but does not have symptoms of the disease • Chemical Hazards -Toxic Heavy Metals – Include Hg, Pb, Cd, As, Se, Cr – By-products of mining, industry, refining – Biomagnifies Mercury & Minamata, Japan • From 1932-1968, Chisso Corp. dumped Hg into • • local bay; didn’t believe inorganic Hg would enter food chain Hg converts to methyl mercury [CH3Hg]+, easier to absorb Symptoms occurred at exposure of 500ppb; first in cats -Organic Compounds – Compounds of C, including synthetics – Do not easily break down, fat soluble, travel long distances – Include dioxins, PCBs (polychloro-biphenols), pesticides (DDT, Aldrin, Dieldrin) DDT PCB general formula Times Beach, Missouri 1982 – Dioxin: one of the most toxic synthetic chemicals; byproduct of herbicide production – Oil sprayed on roads contained 2000x higher dioxin level than in Agent Orange – Town has since been evacuated, purchased by gov’t. – Superfund $ to clean up site through incineration Former Ukranian President Victor Yushchenko, a victim of intentional dioxin poisoning, 2004 Physical Hazardous -Radiation – Workplace Exposure – Byproduct of Nuclear Energy production – Natural sources such as Radon -Particulates – Dust, soot, asbestos – Can be coupled with Heavy Metals & other toxics – Much $ has been spent on asbestos removal; much unnecessary -Thermal Pollution – Heating of water or air – Natural Events: Fires, volcanoes – Man-made: Cooling towers for electric power plants; cools turbines – Eutrophication, fish migration, spawning cycles disrupted, stress on fish -Electromagnetic Fields – – – – Produced by all electrical appliances, power lines Natural fields around us Possible link to childhood leukemia Cell phone use? -Noise Pollution – Any unwanted sound – Measured in decibels; home interior = 45 dB – >140 dB = pain – >80 dB potentially damaging – Airports, mechanical equipment, workplace machinery • Lifestyle/Cultural Exposure -Voluntary – Tobacco, Alcohol – Drug Use (OTC, prescription, illegal) – Driving (texting & cell use) -Involuntary Exposure: -Secondhand smoke -Living near pollution sources -correlates w/socioeconomic Toxicology • Toxicity: measure of how harmful a substance is • Dosage: Amount of substance ingested, inhaled or absorbed through skin • Harmfulness depends on: 1. 2. 3. 4. Size of dosage over certain period of time How often exposure occurs Who is exposed (ex: child vs adult) How well body’s detoxification systems work (kidney, liver, lungs) 5. Genetic makeup that determines one’s sensitivity to a particular toxin Threshold Effects • Level below which no effect occurs; above which effects begin to occur • How much is “safe” vs how much is “realistic” Dosage • LD50: dose that kills 50% of a population (usually mice & rats) • LC: lethal concentration; amt in local env. • ED50: dose effective for 50% of the population • TD50: dose toxic to 50% of population Fig 15.14 In this hypothetical toxic doseresponse curve, toxin A has no threshold. © 2003 John Wiley and Sons Publishers p. 300 Toxicity Ratings and Average Lethal Doses for Humans Toxicity Rating LD50 (mg per kg bodyweight) Average LD Examples Supertoxic < 0.01 < 1 drop Nerve gas, botulism, dioxin Extremely Toxic <5 < 7 drops Potassium cyanide, nicotine, heroin, parathion Very Toxic 5-50 7 drops- 1 tsp Hg salts, morphine Toxic 50-500 1 tsp – 1 oz Pb salts, DDT, caffeine, CCl4 Moderately Toxic 500-5000 1 oz to 1 pt Methyl alcohol, ether, speed, aspirin Slightly Toxic 5000-15000 1 pt to 1 qt Ethyl alcohol, soap Essentially nontoxic >15000 > 1 qt Water, glycerin, sugar