SUBCHRONIC FEEDING STUDY OF 4 WHITE MINERAL-OILS IN DOGS AND RATS

Subchronic 90-day feeding studies were conducted on four highly refine d white mineral oils to determine any potential for toxicity in Long-E vans rats (20 per sex per dose level) and beagle dogs (4 per sex per d ose level). Each oil was fed at dietary dose levels of 300 ppm and 150 0 ppm (w/w). No treatment-related effects of toxicological importance were detected in daily observations of general health or in periodic a ssessments of food consumption and body weight, hematology, serum clin ical chemistry, and urinalysis. Observations in dogs suggested that th e white oils produced mild laxative effects. Gross and histopathologic examinations, as well as measurements of organ weights, did not revea l any macroscopic or microscopic changes which could be due to treatme nt. In addition, special staining by Oil Red O of liver, mesenteric ly mph nodes, spleen, gastrointestinal tract, stomach, and kidneys indica ted no evidence of oil or lipid deposition. A special re-examination o f tissues from female and male rats, in response to more recent confli cting data from the Fischer 344 strain, found no histopathologic signs of macrophage accumulation and/or microgranuloma formation in liver, spleen, or mesenteric lymph nodes. These data indicate that repeated e xposure to relatively high levels of white mineral oils in the diets d oes not produce significant subchronic toxicity in Long-Evans rats or beagle dogs.