Inhalation Toxicology of Oil Mists I. Chronic Effects of White Mineral Oil

Five species of animals (dog, rabbit, rat, hamster, mouse) were exposed daily for periods of from one year to 26 months to a petroleum base mineral-oil mist at concentrations of 5 mg/m3 and 100 mg/m3. Histologic evaluation of tissues of the 100 mg/m3 exposed dogs and rats presented a significant pulmonary alveolar and hilar lymph node oil deposition and/or lipid granuloma formation after 12 months of exposure. In addition, the 100 mg/m3 dogs and rats showed a significant increase in basic and magnesium-activated phosphatase activities. The total evaluation of these studies suggests that the 5 mg/m3 concentration would present no toxic hazard upon prolonged exposure. It would appear, however, that protracted exposure at approximately 100 mg/m3 would in time produce harmful physiologic effects.