Aroclors, toxicity

Commercial PCBs Toxic and Biochemical Effects. PCBs and related halogenated aromatic hydrocarbons ehcit a diverse spectmm of toxic and biochemical responses in laboratory animals dependent on a number of factors including age, sex, species, and strain of the test animal and the dosing regimen (single or multiple) (27—32). In Bobwhite and Japanese quad, the LC q dose for several different commercial PCB preparations ranged from 600 to 30,000 ppm in the diet the LC q values for mink that were fed Aroclors 1242 and 1254 were 8.6 and 6.7 ppm in the diet, respectively (8,28,33). The... 

Hansen, D.J., Parrish, P.R., and Forester, J. (1974). Aroclor 1016-Toxicity to and Uptake hy Estuarine Animals. Environmental Research 7, 363-373. 

Acrylonitrile alone has little tendency to produce duodenal ulcers in animals, but pretreatment with phenobarbital or Aroclor results in a marked increase in the incidence of such ulcers (Szabo et al. 1983, 1984). Although the mechanism of the ulcerogenic effect is not obvious, these data indicate that agents which enhanced mixed-function oxidase activity may also increase the toxicity of acrylonitrile. 

Murk, A.J., J.H. J van den Berg, J.H. Koeman, and A. Brouwer. 1991. The toxicity of tetrachlorobenzyltoluenes (Ugilec 141) and polychlorinated biphenyls (Aroclor 1254 and PCB-77) compared in Ah-responsive and Ah-nonresponsive mice. Environ. Pollut. 72 57-67. 

Quensen et al. [69] showed that micro-organisms isolated from Hudson river sediment dechlorinated most polychlorinated biphenyls in Aroclor 1242 under anaerobic conditions in the laboratory. The higher the polychlorobiphenyl concentration, the more rapid the rate of dechlorination. The possible mechanisms involved are discussed. The products of dechlorination were less toxic than the original compounds and were more readily degraded by aerobic bacteria wastewater containing... 

Polychlorinated biphenyls (PCBs) were manufactured by catalytic chlorination of biphenyl to produce complex mixtures, each containing 60-90 different PCB molecular species or congeners (see Chaps. 1 and 4). In the United States, PCB mixtures were manufactured by Monsanto under the trade name Aroclor and were widely used as dielectric fluids in capacitors and transformers from 1929 to 1978. PCBs are widespread contaminants of aquatic sediments and continue to be a focus of environmental concern because they tend to accumulate in biota and are potentially toxic. The following sections show the most effective bioremediation techniques applied to various PCB contaminated environments ... 

Lepine, F., Milot, S., and Vincent, N. Formation of toxic PCB congeners and PCB-solvent adducts in a sunlight irradiated cyclohexane solution of Aroclor 1254, Bull. Environ. Contam. Toxicol, 48(1) 152-156, 1992. 

D. PCBS. Vos et al. in 1970 were able to identify PCDFs (tetra- and penta-CDFs) in two samples of European PCBs but not in a sample of Aroclor 1260 (k2). The toxic effects of the PCBs were found to parallel the levels of PCDFs present. Bowes et al. examined a series of Aroclors as well as the samples of Aroclor 12 0, Phenoclor DP-6 and Clophen A-60, that had previously been analyzed ( 2). They used packed column GC and mass spectrometry, and found that the most abundant PCDFs had the same retention time as 2,3,7 8-tetra- and 2,3 , 7 8-penta-CDF their results are collected in Table IV 0 3). Using high-resolution GC and MS, Rappe and Buser (unpublished) have analyzed a number of commercial PCBs, and the results are also collected in Table IV. In general the PCBs contained quite a complex mixture of PCDFs, up to UQ different isomers. The highest level of PCDFs was found in a Japanese PCB used for two years in a heat exchange system, which was found to have about 10 yg/g. The dominating isomer was identified as P j tetra-CDF at a level of 1.25 yg/g (UU ]. 

Schoor, W.P. (1975) Problems associated with low solubility compounds in aquatic toxicity tests theoretical model and solubility characteristics of Aroclor 1254 in water. Water Res. 9, 937-944. 

Polychlorinated biphenyls (PCBs) were first synthesized in 1864, and commercial use has been active since 1929. Over 1 million tons of PCBs have been produced commercially with different trade names, such as Aroclor, Clophen, Fenchlor, and Kanechlor. There are 209 PCB isomers or types, which differ from each other in the number and relative position of the chlorine atoms on the biphenyl molecular frame. A small number of these isomers are particularly toxic and are believed to account for the bulk of PCB-induced toxicity in animals. PCBs... 

ATSDR, Toxicological Profile for Selected PCBs (Aroclor-1260, 1224, 1248, 1242, 1232, 1221, and 1016), NTIS Report prepared by Syracuse Research Corp. for the Agency for Toxic Substances and Disease Registry, United States Public Health Service and EPA ATSDR/TP-88/21, PB 89-22403, June, 1989. 

Zhang and Rusling [66] employed a stable, conductive, bicontinuous microemulsion of surfactant/oil/water as a medium for catalytic dechlorination of PCBs at about 1 mA cm-2 on Pb cathodes. The major products were biphenyl and its reduced alkylbenzene derivatives, which are much less toxic than PCBs. Zinc phthalocyanine provided better catalysis than nickel phthalocyanine tetrasulfonate. The current efficiency was about 20% for 4,4 -DCB and about 40% for the most heavily chlorinated PCB mixture. A nearly complete dechlorination of 100 mg of Aroclor 1260 with 60% Cl was achieved in 18 hr. Electrochemical dehalogenation was thus shown to be feasible in water-based surfactant media, providing a lower-cost, safer alternative to toxic organic solvents. 

Studies have been conducted on the interaction of benzene with other chemicals, both in vivo and in the environment. Benzene metabolism is complex, and various xenobiotics can induce or inhibit specific routes of detoxification and/or activation in addition to altering the rate of benzene metabolism and clearance from the body. Toluene, Aroclor 1254, phenobarbital, acetone, and ethanol are known to alter the metabolism and toxicity of benzene. 

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