Chlordane biotransformation

Pyysalo, H., K. Wickstrom, R. Litmanen, P.L. Seppa, U. Koivusaari, and O. Hanninen. 1981. Contents of chlordane-, PCB-, and DDT-compounds and the biotransformation capacity of fishes in the lake area of eastern Finland. Chemosphere 10 865-876. 

Chirality has shown that at least some POPs are not likely to be biotransformed by some fish species. Some legacy POPs were racemic in fish, such as the toxaphene congener B7-1453 in cod liver oil [214], as well as cis- and ira 5 -chlordane, a-HCH, o,p -DDT, and photodieldrin in fish oils purchased from various countries [215]. Arctic cod Boreogadus saida) also had racemic amounts of a-HCH, cis- and ira 5-chlordane, U82, MC-5, and MC-7 [190, 216], as well as MC-6 [216] and PCBs [192]. Emerald rockcod (Trematomus bernacchii) in the Antarctic also had racemic residues of a-HCH [195]. 

As with polar bears, wolverines and Arctic foxes also appear to have sizable capacity for biotransforming POPs, as evidenced by enantiomer analysis. Wolverines captured from Iceland and the Canadian Arctic had enrichments of (—)-PCBs 136 and 149 in livers, with mean EFs of 0.41 and 0.46, respectively [268]. While these enrichments were similar to those of a-HCH (mean EF of 0.42) and heptachlor epoxide (mean EF of 0.55), they were not as stereoselective as those of /ra 5-chlordane (mean EF of 0.65) and oxychlordane (mean EF of 0.71) [268]. Populations of Arctic foxes in Iceland feeding mostly on marine mammals had much higher POP concentrations in liver tissue than those with a terrestrial diet, but had similar enrichments of (-l-)-chlordane [267]. As with wolverines, Arctic fox livers [268] had modest enrichments of (—)-a-HCH, (+)-PCBs 136 and 149, and El -PCB 95 on Chirasil-Dex, with mean EFs of 0.41, 0.48, 0.54, and 0.55 respectively. These enrichments were again minor compared to that of the OC compounds, which had mean EFs of 0.61 for cw-chlordane, 0.89 for /ra 5-chlordane, 0.68 for oxychlordane, and 0.73 for heptachlor epoxide. Depletions of labile analytes compared to recalcitrant compounds... 

The strong lipophilicity and relatively weak hydrophilicity of chlordane and its metabolites suggest that excretion would be largely by passive diffusion. This is supported by the observation that fecal (biliary) excretion exceeds urinary excretion in humans and rats (Aldrich and Holmes 1969 Ohno et al. 1986), indicating that renal tubular excretion is probably not a major factor in excretion. Passive tubular resorption probably accounts for the lesser role that renal excretion plays in the fate of chlordane, compared with most organic chemicals, for which biotransformation results in the formation of more polar (hydrophilic) products. 

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