Abstract
The United States holds the world's largest and richest deposits of oil shale. If this resource is to have a role in meeting future energy needs, it must be developed in accordance with the nation's health and environmental objectives. Previous oil shale operations in Scotland and Estonia are reviewed, along with the limited United States experience. A possible carcinogenesis hazard is suggested, based upon occurrence of skin cancers in Scottish workers. The API supported toxicologic studies to define potential health hazards related to oil shale. Analysis of crude retort oils revealed the presence of carcinogens in the polyaromatic hydrocarbon fraction. Bacterial screening tests for mutagenic activity were positive following enzymatic activation, and cancers were produced by painting the oils on the skin of mice. Tests for acute toxicity showed an oral LD50 of 8–10 g/kg, and a dermal LD50 of 20 g/kg for the crude retort oils which produced liver damage. Further processing of the retort oils by hydrogenation will reduce these toxic effects. Controls to prevent inhalation of raw and spent shale dusts (which contain SIO2) and contact with retort oils are indicated. Comparisons between oil shale and petroleum industries are useful in evaluating health risks.