A STUDY OF AUTOANTIBODIES AND CIRCULATING IMMUNE-COMPLEXES IN MERCURY-EXPOSED CHLORALKALI WORKERS

Inorganic mercury may cause immunologically mediated disease: e.g., gl omerulonephritis, acrodynia, and contact allergy. Animal models have d emonstrated the importance of genetic factors in determining susceptib ility and resistance to autoimmunity, as well as the specific manifest ation of the autoimmune response. Findings in groups of workers with o ccupational exposure to inorganic mercury have been inconsistent. Obje ctive: To investigate whether an immune response, caused by exposure t o inorganic mercury (Hg), could be shown in occupationally exposed wor kers. Methods: Immunoglobulin G (IgG), antinuclear autoantibodies, ant ibodies against thyroid, stomach or kidney antigens using indirect imm unofluorescence, antibodies against glomerular basement membrane using ELISA, and circulating immune complexes in serum, and albumin in urin e, were examined in HE-exposed workers and controls. The two groups, 4 1 male chloralkali workers exposed to Hg vapour (mean exposure time 9 years) and 41 unexposed controls were age-matched and recruited from t he same company. Hg concentrations in whole blood (B-Hg), plasma (P-Hg ), and urine (U-Hg) were determined using cold vapor atomic spectromet ry. Design: Cross-sectional study. Results: The mean B-Hg, P-Hg and U- Hg levels were 46 nmol/l, 37 nmol/l, and 27 mu g/g creatinine in the e xposed group, and 17 nmol/l, 6.9 nmol/l, and 3.4 mu g/g creatinine in the referents. No statistically significant differences were found reg arding IgG levels, urinary albumin excretion, prevalence of abnormal t iters of autoantibodies or circulating immune complexes. There were no statistically significant associations between autoantibodies or immu ne complexes on the one hand and mercury exposure indices on the other . Conclusion: The results indicate that, if and when lasting autoimmun e response occurs at the mercury exposure levels of the present study, it is uncommon. A small fraction of humans may, however, be susceptib le to the development of autoimmunity, and there is also a possible '' healthy worker'' selection. Thus cross-sectional studies of moderate n umbers of active workers will have low power to demonstrate autoimmune effects.