Induction of Aryl Hydrocarbon Hydroxylase Activity in Cell Cultures by Aroclors, Residues from Yusho Oil Samples, and Polychlorinated Biphenyl Residues from Fish Samples

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Abstract
Four Aroclor reference materials, cleaned-up extracts of 2 Yusho rice oil samples, and cleaned-up extracts of 3 fish samples containing polychlorinated biphenyl (PCB) residues were tested for their ability to induce aryl hydrocarbon hydroxylase (AHH) activity in a rat hepatoma cell line. Before the AHH bioassay, the samples were fractionated by a Florisil column chromatographic method. All samples contained about 1000 fig PCBs before Florisil column chromatography. The first Florisil eluate contains about 95% of the PCBs in a typical Aroclor, and the second contains the more polar or adsorbent PCB congeners. In this study, the first eluate for all samples produced no quantifiable AHH activity. The second Florisil eluates of both Aroclors 1242 and 1248 induced AHH activity, whereas these eluates of both Aroclors 1254 and 1260 did not. This difference may be due to the presence in Aroclors 1242 and 1248 of 3,3',4,4'-tetrachlorobiphenyl, which has not been detected in Aroclors 1254 and 1260. The second Florisil eluates of the fish samples induced somewhat less AHH activity than did Aroclor 1242 or 1248. The second Florisil eluates of the PCB residues from Yusho rice oil samples induced significantly greater AHH activity than these eluates of either Aroclor 1242 or 1248, perhaps because Yusho rice oil contains a greater amount of polychlorinated dibenzofurans than PCB commercial mixtures on a PCB equivalent basis.