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77 workers in an asbestos factory were checked for the presence of circulating antinuclear, anti-smooth-muscle antibodies, antigastric parietal cells and antimitochondrial antibodies and their serum immunoglobulin levels were estimated (IgA, IgG, IgM). Antinuclear antibodies were detected in 8 of the patients with asbestosis (16 persons) and in 4 of those exposed to asbestos for a long time and with no signs of asbestosis in the chest X-ray (20 persons). Sporadic occurrence of other autoantibodies was detected mainly in the patients with asbestosis. The changes were not found in the individuals who had been exposed to asbestos only for a short time (22 persons) or in workers in the same factory who had not been in direct contact with asbestos (19 persons). Similar results were obtained when the immunoglobulin levels were studied. Significantly higher IgA, IgG, and IgM levels were found in the patients with asbestosis and in those exposed for a long time than in the remaining control groups. A higher incidence normal results was observed in the group who had been exposed to asbestos for long periods and in whom no pulmonary changes were observed. Thus, the observed immunologic disturbances correlate with the duration of exposure to asbestos, and the most pronounced changes were seen in the patients with pulmonary radiographic changes.

Immunoglobulin levels in the sera of 35 workers occupationally exposed to benzene, toluene and xylene were studied by means of a simple radial immunodiffusion. The immunoglobulin levels were compared with those of a control group of 42 healthy adults. A statistically significant decrease was observed in the IgG and IgA levels, accompanied by an increase in the IgM level. It is possible that this observation reflects a suppressive action of benzene on immunoglobulinproducing cells, resulting in the inhibition of DNA synthesis.