Distinctive patterns of autoimmune response induced by different types of mineral oil.
White mineral oils have a long history of safe use by humans in orally ingested and topically applied products. A re-evaluation of the use of certain mineral hydrocarbons in the preparation of food items by regulators in the UK, however, has prompted additional safety studies and a critical assessment of the toxicological effects of white mineral oils. As white mineral oils are present in many topically applied drug and non-drug products, it is of interest to review the toxicological effects of mineral oil produced by this route of exposure. Specifically, the concern regarding the safety of white mineral oils has arisen, in part, from results of subchronic (e.g 90 day) feeding studies that reported the presence of granulomas in liver and histiocytosis in mesenteric lymph nodes of Fischer 344 rats after oral ingestion of select white mineral oils. In contrast to these subchronic oral studies, repeated topical exposure to white mineral oils has not been found to produce liver granulomas, histiocytosis in the mesenteric or other lymph nodes, or any local or systemic toxicity including tumour formation in Fischer 344 rates, C3H mice, New Zealand White rabbits or beagle dogs at similar or higher exposures (mg/kg/day). On the basis of these findings and reports on negligible epidermal penetration of topically applied white mineral oils, there is no evidence of any hazard identified for topical exposure to white mineral oils at any dose in multiple species. This conclusion is supported by the long and uneventful human use of white mineral oils in drug and non-drug topically applied products.