(1) No correlation was found between lung cancer and severity of the radiological category, the type of silica (coal or metalliferous mines, quarries etc), or the degree of exposure to silica dust.
(2) The ability of pathogenic mineral, fibrous and metalliferous dusts to stimulate PMN to produce potentially injurious free radical oxidants, has been studied using an in vitro chemiluminescent technique.
(3) The Wistar rats were intratracheally administered 50 mg of PbO dust, the same amounts of metalliferous dust from one of lead--and zinc works and of ferrotungsten dust, and 10--15 mg of cadmium dust (greater doses of cadmium dust resulted in animals' death).