Epidemiologic studies of Scottish oil shale workers: I. Prevalence of skin disease and pneumoconiosis.

In an epidemiologic study of 6,359 oil shale workers, 1,664 (46.7%) of 3,566 survivors were investigated. No excess of skin disease (as reported in response to a questionnaire) was found in men exposed to oil or dust, whether compared to men who were not exposed to oil or dust or to coalminers. A low prevalence of simple pneumoconiosis was found in workers exposed to dust, while progressive massive fibrosis occurred in approximately 1% of miners and retort workers. Comparisons of responders with nonresponders revealed no serious bias in terms of age or work experience, though nonresponders were likely to have been less healthy in general.