Absorption and toxicity of mineral oil after dermal and mucosal surface exposure: a review.

Abstract

Dermal and mucosal surface exposure to mineral oils occurs in the occupational setting. To evaluate exposure levels at which toxicity occurs, we collected data on non-cancer toxicity of crude oil, refinery streams and refined mineral oils. This included extraction of no-observed-adverse-effect levels (NOAELs) and lowest-observed-adverse-effect levels (LOAELs). Concerning biokinetics, whole oils appear to have low skin penetration, while polycyclic aromatic hydrocarbon (PAH) fractions penetrate to a considerable extent. Concerning toxicity of crude oil, reported local effects in humans include skin rash and eczema. In animals, a LOAELSkin irritation was 0.4 mg/cm2. Systemic effects of crude oils include a LOAELDevelopmental effects of 30 mg/kg body weight (bw). Concerning refinery streams, local effects of syntower bottoms showed a LOAELSkin histopathology of 0.1 mg/cm2. Catalytically-cracked clarified oil had a LOAELIrritation of 3 mg/cm2; a systemic LOAEL on maternal body weight and developmental toxicity of clarified slurry oil was 1 mg/kg bw (NOAEL: 0.05 mg/kg bw). Systemic effects of refinery streams correlated with PAH content (mainly driven by one study). Concerning refined mineral oils, local effects reported in mechanics and metal workers include contact dermatitis, oil acne and nose and throat irritation (exposure involved used oils and other chemicals). A human LOAELskin occlusion of refined oil was 2 mg/cm2; in animals, skin irritation had LOAELs as low as 15 mg/cm2 (NOAEL: 7.6 mg/cm2). Systemic effects of refined oils in rats included a LOAELDepressed body weight of 160 mg/kg bw. In conclusion, both local and systemic effects are observed after dermal exposure to mineral oils.