The carcinogenic initiating and promoting properties of a lightly refined paraffinic oil.
The dermal carcinogenic potential of some petroleum-derived liquids is related to the polycyclic aromatic hydrocarbon (PAH) content. However, repeated application of middle distillates (MDs), e.g., kerosene, diesel fuel, and heating oil, produced tumors in mouse skin. This result was unexpected since the MDs typically contain very low levels of biologically active PAHs. The present study examined the tumorigenic mechanism of a lightly refined paraffinic oil (LRPO), an MD shown to be active in mouse skin. The LRPO was separated into saturated and aromatic fractions. Whole LRPO and various fractions were tested for mutagenic activity in the Salmonella assay and for carcinogenic initiating and promoting activity. There was no evidence that any of the samples examined were mutagenic in bacteria or carcinogenic initiating agents in mouse skin. Thus no support was provided for the hypothesis that the complete tumorigenic activity of LRPO was in any way related to the presence of low levels of PAHs or to an interaction between initiating and promoting constituents. There was evidence that LRPO was a weak promoter of dimethylbenzanthracene (DMBA)-initiated mouse skin. It was also found that repeated application of LRPO produced chronic irritation and hyperplasia, and this may have been responsible for the promotional effects. Based on these data, it seemed likely that the complete carcinogenic activity of this class of products is also the result of an epigenetic process related to skin irritation.
McKee
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Exxon Biomedical Sciences, Inc., East Millstone, New Jersey 08875-2350.
Plutnick
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RT
Przygoda
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RT
D000818:Animals; D002273:Carcinogens; D008297:Male; D051379:Mice; D009821:Oils / Q000633:toxicity*; D010232:Paraffin / Q000633:toxicity*; D051381:Rats; D011919:Rats, Inbred Strains; D012486:Salmonella typhimurium / Q000235:genetics; D012867:Skin / Q000187:drug effects
D002273:Carcinogens; D009821:Oils; D010232:Paraffin