Question 46 Why is it that Biomagnification can cause a contaminant in lipid tis
ID: 87855 • Letter: Q
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Question 46
Why is it that Biomagnification can cause a contaminant in lipid tissue of a fish to become much greater than one would calculate using the ambient water concentration and the K_ow? Why does biomagnification cause contaminant levels to generally increase in fish the older the fish? If you eat only "organic" food, will you really avoid dioxins and PCBs in your diet? Why/why not? In organophosphate pesticides, what kind of linkage is present? Name it and draw it using R groups to denote some kind of organic chain. Aldicarb is a carbamate. What's the linkage present, and is it an insecticide or herbicide? Permethrin is a synthetic pesticide that is based on what kind of natural structure, and is it an insecticide or herbicide? Why isn't the pesticide 2, 4, 5-T manufactured any more? And is it an insecticide or herbicide?Explanation / Answer
Biomagnifications refers to increase in tissue concentrations of a contaminant as it passes from one tropic level to another. In aquatic organisms, lipids serve as a protective reservoir as the toxic, persistent organic chemicals are generally lipophilic. Further, lipid soluble compounds are stored in at tissues and thus are less available for metabolism and therefore elimination. The partition equilibrium theory plays a role in determining the concentration of contaminants in water, blood and tissue lipids. It has been observed that lipophilic substances with octanol-water partition coefficient ( log Kow > or = 5) tend to biomagnify in aquatic animals.
The older fish belonging to higher trophic levels require to consume more prey (containing toxin) to meet the energy requirements. This leads to higher concentration of the toxin in lipid tissues of fish.
Organic foods generally contain less number of pesticides and toxins. Dioxins and PCBs may accumulate at higher levels in organic animal products, or organic vegetables grown in soils contaminated from residues of volcanic eruptions/ forest fires/ industrial processes.
Organophosphates have ester linkages, they are esters o phosphoric acid and its derivatives. They typically contain a central phosphorus atom, and phosphoric (P=O) or thiophosphoric bond (P=S).
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P ==== O(S)
Permethrin is an insecticide belonging to pyrethroid family. It acts similar to natural extracts (Pyrethrum or pyrethrin) from chrysanthemum flower which protect the plant from insects. It affectsthe neurological system of insects like bedbugs, ticks, fleas and chiggers.
2,4,5-tricholorophenoxy acetic acid is herbicide. Ingestion of this chemical had side effects such as nausea, head ache, weakness, hypotension and delayed neuropathy. The use of this chemical was terminated by US department of Agriculture owing to its side effects in 1970.
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