Light White Oils Exhibit Low Tissue Accumulation Potential and Minimal Toxicity in F344 Rats

Female F344 rats were fed diets containing 0.02%, 0.2%, or 2.0% white mineral oil for 90 days. There were no gross or microscopic differences in target organs at the 0.02% level. In the higher-dose groups, relative liver and mesenteric lymph node (MLN) weights were increased, and MLN inflammation was observed. At the 2% level, there was very limited evidence of microgranuloma formation in the liver but at a lower incidence and at lesser severity than has been reported in studies of C₂₂-C₂₅ oils. Analysis of liver extracts from treated rats revealed that C₁₅-C₂₀ constituents were underrepresented by comparison to their corresponding concentrations in the test oil. These results provide evidence that although hydrocarbons with carbon numbers < C₂₀ are absorbed, they are not preferentially retained and do not contribute to inflammatory processes in liver.