Oil mists and vapours: A review of exposure and toxicity, with dose descriptors from inhalation studies

Inhalation of oil mists and vapours may induce adverse effects. Here we review the literature on human exposure to oil mists and vapours and their toxicity following inhalation exposure. We collected data on inhalation of all types of oils, on all toxicity endpoints other than genotoxicity and cancer. Toxicological dose descriptors (no-observed-adverse-effect concentrations (NOAECs) and lowest-observed-adverse-effect concentrations (LOAECs)) were collected to identify exposure levels at which toxicity occurs. Occupational mean exposure concentrations typically range from 0.2 to 5 mg/m³ for mist and up to 36 mg/m³ for vapours during oil drilling. Affected toxicological endpoints in humans of exposure to refined oil include lung function, lung pathology (including fibrosis), asthma and irritation of nose and throat. Sudden death has been reported after acute exposure to hydrocarbon gas and vapour (e.g. during oil tank hatch operation, potentially involving oxygen deficiency). In animals, endpoints affected include lung function, lung pathology, increases in pulmonary immune cells, decreased body weight and in one study on monkeys also lethality. Dose descriptors in human studies with exposure to mineral oil mists included LOAECs as low as 0.3, 0.4. 0.5, 0.7 and 2.2 mg/m³ concerning lung function/respiratory symptoms. In general, higher dose descriptors were observed in animal studies, e.g. LOAECs for lung pathology of 50 mg/m³ in rats and 63 mg/m³ in monkeys. In conclusion, toxicological effects were observed in humans at occupationally relevant exposure levels. The collected data inform hazard assessment of airborne oil at the workplace and in society.