PCBs and Their Metabolites

Detoxification of PCBs by Phase I conjugation produces hydroxylated PCBs (OH-PCBs) through either direct hydroxide insertion or via arene oxide intermediates [7]. The latter can 

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Furukawa, K., Tomizuka, N., Deck, B.L. Koystyk, N. (1982). Bacterial degradation of polychlorinated biphenyls (PCB) and their metabolites. Advances in Experimental Medicine and Biology, 136A, 407-18. 

January 1992, two working groups have been dealing with analytical methods for the determination of pesticide residues WG 3 Pesticides and PCBs in Fatty Foods and WG 4 Pesticides in Nonfatty Foods . So far analytical methods for 47 pesticides and their metabolites in fatty food and methods for more than 200 pesticides in nonfatty foods have been published in several standards (Table 6). 

Recently, the PCB-biodegradative capabilities of methanotrophs have been demonstrated (Adriaens, 1994). In this study, 2-CB was oxidized by a methanotrophic culture (CSC1) to a hydroxylated chlorobiphenyl intermediate identified as 2-hydroxy-3-chlorobiphenyl. This intermediate indicated that the metabolite was formed via a concerted oxidation involving an arene oxide which rearranges spontaneously via an NIH shift. No studies have shown, however, that methanotrophs can degrade more highly chlorinated PCBs, and their utility for bioremediation processes does not seem promising. 

Wong, C.S. Chiral polychlorinated biphenyls and their metabolites In PCBs Human and Environmental Disposition and Toxicity, L.G. Hanson L.W. Robertson, editors. University of Illinois Press Urbana IL, 2008, p. 30-50. 

Karasek, L. Hajslova, J. Rosmus, J. Huhnerfuss, H., Methylsulfonyl PCB and DDE metabolites and their enantioselective gas chromatographic separation in human adipose tissues, seal blubber and pelican muscle Chemosphere 2007, 67, S22-S27. 

Under Michael s direction AccuStandard is the first and only company to have synthesized all 209 PCB congeners, and is currently the leading manufacturer of PBDE congeners and their metabolites and has published papers on these subjects. AccuStandard routinely interfaces with regulatory agencies such as the USEPA, as well as universities and private interests worldwide to facilitate their research through the production of high quality reference materials. 

Fish eaten by people residing in northern Norway are contaminated with PCBs, chlorinated pesticides, and their metabolites. Fish living in mangrove habitats in Singapore are contaminated with polybrominated diphenyl ethers (PBDEs). I5 Dioxins and PCBs are found in the eggs of free-range chickens. 

It seems appropriate to add some brief comments on birds since it was the attention directed to the effect of agrochemicals on these which effectively mobilized public awareness of the environmental hazard of chemicals. Apart from the adverse effects of toxicants on birds, they may also play an important role in the dissemination of xenobiotics and their metabolites produced by endogenous metabolism. Although birds may possess lower levels of microsomal monooxygenase enzymes which are involved in the metabolism of xenobiotics than fish (Walker 1983 Ade et al. 1984), like mammals they seem to have phenobarbital-inducible systems that mediate the metabolism of important PCB congeners (Buhler and Williams 1988). 

Cyclodiene pesticides and their metabolites were investigated in aqueous media using an extraction method with Mixxor reservoirs. The efficiency of the extraction was found to be between 60-88% (23b) (Table 1). More than 80 pesticides and 12 PCBs were examined in different samples using n-hexane extraction and treatment with cone. H2SO4. The decomposition of the residues caused by the strong unorganic acid was investigated (23c) (Table 1). 

Many of the components of PCB and PBB mixtures are both lipophilic and stable, chemically and biochemically. Similar to the persistent organochlorine insecticides and their stable metabolites, they can undergo strong bioconcentration and bioaccumulation to reach relatively high concentrations in predators. 

Analysis of chlorobenzoates in sediments, which had been contaminated with PCBs, was used to demonstrate that the lower PCB congeners that had initially been produced by anaerobic dechlorination were subsequently degraded under aerobic conditions. The chlorobenzoates were transient metabolites and their concentrations were extremely low since bacteria that could successfully degrade them were present in the sediment samples (Elanagan and May 1993). 

Meanwhile, in laboratory studies the metabolism of PCBs and DDE was also confirmed by detection of their metabolites.63 Based on the many laboratory studies with terrestrial mammals (rodents mainly) and the work mentioned above, it is now believed that biotransformation occurs in three phases ... 

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