Question 38 In the context of the above problem, it is worth watching the Couste

Question

Question 38

In the context of the above problem, it is worth watching the Cousteau PBS special "Call of the Killer Whales" http;//video.pbs.org/video/1099394282/. In that video, what chemical tests did they do to compare what was going on with the whales and seals with what is happening to humans? In the chlorinated dibenzofuran group, how many possible different mono chloro congeners are there? The basic dibenzofuran structure is provided below. In the dibenzofuran group, how many octachloro congeners are there? (that's 8 Cl).

Explanation / Answer

Each concentration of an individual congener in a mixture is multiplied with its TEF, and the resulting TCDD equivalents are added up and expressed as WHO-endorsed toxic equivalents (WHO-TEQ). Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are mainly the by-products of industrial processes (such as metallurgical processing, bleaching of paper pulp, and the manufacturing of some herbicides and pesticides) but they can also result from natural processes like volcanic eruptions and forest fires. Waste incineration, particularly if combustion is incomplete, is among the largest contributors to the release of PCDDs and PCDFs into the environment. Due to their persistence, PCDDs, PCDFs and PCBs are part of the so-called persistent organic pollutants group of compounds that also include some chlorinated pesticides. Since they have a high lipophilicity and resist transformation, they bio-accumulate in animal and human adipose tissues

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