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The object of this work was to investigate possible interactions of mercury, cadmium and selenium in humans. Selenium and cadmium in blood and urine were determined in this cross-sectional study of 130 males, of whom 77 had been previously exposed to mercury vapour at a chloralkali plant. Of the participants, 61.5% were smokers and 16.2% werenever-smokers. The concentration of selenium in blood (B-Se) was significantly lower in subjects currently smoking more than 50 g of tobacco per week compared to never-smokers, whereas the concentration of cadmium in blood (B-Cd) was significantly higher in all categories ofcurrent smokers. In the multiple linear regression analysis, B-Se asa dependent variable was negatively associated with B-Cd, whereas current smoking habits were not included in the model as a predictor variable. In contrast, B-Cd as a dependent variable was positively associated with current as well as previous smoking habits, and negatively with both B-Se and the 'cumulative dose'of previous mercury vapour exposure. The concentration of selenium in blood was also negatively associated with B-Cd in the group of never-smokers (Spearman's r = -0.80; P < 0.001). In conclusion, these results suggest a depressive effect of cadmium on the concentration of selenium in blood, while smoking alone did not operate as a true predictor for this effect. Furthermore, previous exposure to mercury apparently modifies the concentration of cadmium in blood. [ABSTRACT FROM AUTHOR]

Neurological and neurophysiological examinations were conducted in 77 former chloralkali workers previously exposed to mercury vapour and 53 referents. The exposure had ceased on average 12.3 years prior to the study. There was a higher prevalence of reduced distal sensation (13.0% vs 1.9%), postural tremor (18.2% vs 7.5%) and impaired coordination (10.4% vs 1.9%) among the exposed subjects as compared to the referents. Abnormal Romberg's test (6.5% vs 0%) and line walking (7.8% vs 0%) were also more prevalent. The first negative peak in visual evoked response (N75) was bilaterally prolonged, and the median motor (55.9 m/s vs 58.0 m/s) and sensory nerve conduction velocity (55.6 m/s vs 59.0 m/s) were slightly reduced among the highly exposed subjects. The results indicate that slight neurological abnormalities, which in most cases could not be classified as disease, may persist many years after exposure cessation.