Characterisation of exposure to total and hexavalent chromium of welders using biological monitoring.

Inhalation exposure to total and hexavalent chromium (TCr and HCr) was assessed by personal air sampling and biological monitoring in 53 welders and 20 references. Median inhalation exposure levels of TCr were 1.3, 6.0, and 5.4 microg/m(3) for welders of mild steel (MS, <5% alloys), high alloy steel (HAS, >5% alloys), and stainless steel (SS, >26% alloys), respectively. The median exposures to HCr compounds were 0.23, 0.20, and 0.08 microg/m(3), respectively. Median concentrations of TCr in urine, blood plasma and erythrocytes were elevated in all welders, compared with the corresponding median concentrations in the reference group (p<0.005). The TCr levels observed in plasma were two-fold higher in welders of SS and HAS than in welders of MS (p<0.01). Exposure to HCr as indicated by median total content of Cr in erythrocytes was 10 microg/L in welders of SS, MS and HAS. Uptake of TCr during the shift was confirmed for welders of SS by a median increase of urinary TCr from pre- to post-shift of 0.30 microg/g creatinine. For welders of MS and HAS as a group TCr was not increased.