Journal of School of Public Health and

Background and Aim: Exposure to hexavalent chromium in plating operations is associated with skin ulceration, contact dermatitis, respiratory tract irritation, cancer, and kidney damage. We investigated the possibility of using biological monitoring to assess exposure to hexavalent chromium in chrome-plating workers. We compared mean Cr6 concentrations in the breathing zone plus urine chromium, β2 microglobulin (B2M), and N-acetyl-B-D- glucosaminidase (NAG) at the end of the working shift. Then we assessed the correlation between exposure to hexavalent chromium and biological indicators.

Materials and Methods: This study involved 45 chrome platers (Cases) and 40 zinc platers (Controls) in Isfahan. Air and urine samples were collected at the end of the work shift. Measurement of Cr6 concentrations in the workers' breathing zone was performed using the NIOSH Methods 7600. Urine Cr levels were determined by atomic absorption spectrophotometry, with a graphite furnace (Shimadsu, AA680). B2M and NAG were measured by Kits.

Results: Overall, geometric mean of hexavalent chromium concentrations in the breathing zone was significantly higher among chrome platers (14.577 μg/m3) compared to zinc platers (0.862 μg/m3, p<0.001). Moreover, the mean urine Cr concentrations were higher in chrome platers (9.198 vs. 1.811 μg / g creatinine, p<0.001). Similarly, there were significant differences between mean NAG in chrome platers (12.608IU/gr creatinine) and zinc platers (6.824 IU/g creatinine, p<0.001). Differences in B2M concentrations were not significant (p>0.05). A significant correlation was found between Cr6 concentrations in the chrome platers' breathing zone and their urinary chromium levels (r= 0.838, p<0.001). A similar association was found between concentrations of Cr6 and NAG in the breathing zone (r= 0.304, p<0.05).

Conclusion: As urinary B2M concentration did not change significantly, it may not be a sensitive indicator in evaluating exposure to hexavalent chromium. There were significant differences between mean urinary Cr and NAG concentrations in the two groups. The significant correlations between Cr and NAG concentrations indicate that these markers may be suitable indicators of exposure to hexavalent chromium. Our results indicate that NAG is an early indicator of renal dysfunction in chrome platers.