Objectives The aim of this study was to investigate renal function and immunologic markers among chloralkali workers with long-term low exposure to mercury vapor.

Methods Forty-seven currently exposed workers were compared with reference workers matched for age in a cross-sectional design.

Results The mean urinary mercury concentration was 5.9 (range 1.1–16.8) nmol/mmol creatinine (Cr) for the exposed workers and 1.3 (range 0.2–5.0) nmol/mmol Cr for the referents. The chloralkali workers had been exposed for an average of 13.3 (range 2.8–34.5) years. The activity of N-acetyl-β(-D-glucosaminidase in urine (U-NAG) was higher in the exposed workers (mean 0.18 U/mmol Cr versus 0.14 U/mmol Cr, P=0.02). Associations between current urinary mercury, cumulative urinary mercury, and cumulative urinary mercury per year (intensity) and U-NAG, autoantibodies to myeloperoxidase (anti-MPO) and proteinase 3 in serum, respectively, were observed. The activity of U-NAG and anti-MPO was increased in the workers with the highest exposure, as assessed by their mean intensity of exposure. The highest activity of U-NAG was observed in the exposed workers with the lower concentrations of selenium in whole blood.

Conclusions The study indicates an effect of exposure on the kidney proximale tubule cells, possibly modified by individual selenium status, and an effect mediated by neutrophil granulocytes.

Key terms autoantibodies to myeloperoxidase; urinary N-acetyl-beta-D-glucosaminidase