ES2 Midterm II

ES2 Midterm II - Chapter 8Environmental Health, Pollution,...

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Chapter 8—Environmental Health, Pollution, and Toxicology 1) Case Study —Demasculinization and Feminization of Frogs in the Environment a. Frogs that are exposed to the weed killer, atrazine often display gonadal abnormalities. b. The weed killer is dumped into bodies of water around the natural habitat of frogs, and the frogs are particularly vulnerable to be affected during their metamorphoses from tadpole to frog c. Such substances that interact with the hormone system of an organism is known as hormonally active agents or HAA’s d. This story brings attention to the detrimental effects human chemicals have on the environment. 2) Basic Terminology a. Disease is often due to a poor balance or adjustment between the individual and the environment i. Incidence of disease is dependent on other factors including physical environment, biological environment, and lifestyle b. Humans are not the only contributors of natural toxins into the environment i. i.e. Volcanoes produce potentially toxic sulfur dioxide, Radon Gas, Carbon Dioxide (Lake Nyos), Asbestos in Water, Wildfires c. Pollution—an unwanted change in the environment caused by introducing harmful materials or producing harmful conditions d. Contamination—implies making something unfit for a particular use though the introduction of undesirable materials e. Toxin—is a substance that is poisonous to people and other living things, Toxicology is the study of chemicals that are or could potentially be toxic i. Carcinogen—is a toxin that increases the risk of cancer f. Synergism—is the interaction of different substances, resulting in a combined effect that is greater than the effects of the separate substances i. Sulfur Dioxide and coal dust when combined create a very deadly toxin because the sulfur dioxide binds with the coal dust making it easy to breathe deep into one’s lungs 3) Sources of Pollutants a. Point Source—often introduces toxins and pollutants into the environment from a single point i. i.e. smokestacks, pipes discharging etc. b. Area Sources—More spread out over a vast area i. i.e. agricultural use of pesticides c. Mobile Sources—Moving sources i. Automobile exhaust 4) Categories of Pollutants a. Toxic Heavy Metals—Mercury, thallium, and lead are very poisonous to people b. Toxic Pathways -- Biomagnification—The accumulation or increase in the concentration of a substance in living tissue as it moves through a food
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web i. The higher up on the food chain, the higher the concentrations of said chemical 1. Lead and the Urban Environment 2. Mercury and Japan mercury enters aquatic system in inorganic form and methylation occurs creating a much more toxic substance. As the new methyl works its way up the food chain, it becomes more and more toxic a. Disease of Cat’s in Japan—large mercury poisoning outbreak as a result of poor discharging practices c. Persistent Organic Pollutants (POP’s) i. Typically carbon based containing chlorine, synthetic chemicals,
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ES2 Midterm II - Chapter 8Environmental Health, Pollution,...

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