Lung diseases associated with hydrocarbon exposure

• A review of the toxic effects of hydrocarbon exposure on the lung.
• Radiology and pathology of diseases due to environmental and occupational exposure.
• Highlights the potential for petroleum by-products to cause COPD and lung cancer.
• Reviews the association between diesel exhaust particles and allergic manifestations.
• Raises questions regarding the long term effects of lower levels of hydrocarbon exposure.

The human race has been exposed to the potential toxicity of hydrocarbons, whether by the inhaled or ingested route, for thousands of years and the consequent inflammatory reaction in the lungs depends on the degree of exposure, volatility and viscosity of the particular hydrocarbon in question. Heating, lighting, transportation, industry and nature all provide the potential for both inhalation and/or ingestion of hydrocarbons. Some forms, such as those related to petroleum products, e.g. diesel exhaust particles (DEP) and polycyclic aromatic hydrocarbons (PAH) have been shown to cause both malignant and non-malignant respiratory diseases. Accidental ingestion represents another significant exposure risk and we now have increasing evidence that pollutant particles may adsorb allergens to their surface and potentially enhance the allergic response. It seems unlikely that this potential will significantly decrease in the near future and depending on individual socio-economic circumstances, work environment and habitation, the risks of significant lung disease will vary. This review outlines the domestic, outdoor, occupational and natural sources of hydrocarbon exposure and considers the evidence relating to radiological and pathological lung changes in both animals and man. The acute effects of hydrocarbon toxicity are well recognised but the effects of longer term, lower exposure, and the mechanisms of their toxicity, require further research.