Health effects have been documented among American
vermiculite workers who mined and processed
vermiculite contaminated with
amphibole asbestos, viz.,
tremolite-
actinolite. Workers mining and processing South Africa
vermiculite (N = 172), which contains very little
asbestos, underwent x-ray examination and lung function testing and completed a respiratory symptom questionnaire. The
vermiculite workers were compared with other workers involved in the mining or refining of
copper. Only two of the
vermiculite workers showed evidence of small opacities of 1/0 or more (according to the ILO 1980 classification); lung function was comparable with the other groups of workers, and there was no excess of respiratory symptoms among the
vermiculite workers. It is concluded that workers exposed to
vermiculite that is minimally contaminated with
asbestos are probably not at risk for
pneumoconiosis, lung function impairment, or respiratory symptoms. It is likely that the health effects observed in other studies of
vermiculite workers are the result of concomitant
asbestos exposure. A risk of
mesothelioma caused by the fiber content of the
vermiculite cannot be excluded by this study.