Silicosis in diatomaceous earth factory workers in Sweden.

Kieselguhr is a greyish-white powder which is made by heating lake ooze containing diatom skeletons to a temperature of about 1000 degrees C. It contains quartz, cristobalite and tridymite. Working with kieselguhr can induce silicosis. In Sweden six cases of silicosis caused by exposure to kieselguhr have been reported to the Worker's Protection Board. The time of exposure was relatively short. New cases have not appeared in the last 20 years. It seems, nevertheless, important to document this unusual form of silicosis, as diatomaceous earth is readily available and the manufacturing process is simple. Demand for kieselguhr has increased and new factories are to be established which may result in new cases of silicosis.