Biological monitoring of occupational exposure in the chromate pigment production industry

A survey of occupational exposure to hexavalent chromium in chromate pigment production was undertaken in factories producing lead chromate (PbCrO4) and strontium chromate (SrCrO4). Sampling pre and post-shift in a factory where SrCrO4 production had just started showed the optimum strategy for biological monitoring is the measurement of urinary chromium, in urine samples taken at the end of Friday shift and pre-shift the following Monday. However, short-term uptake may be assessed under these circumstances by the increase in urinary chromium over a shift. Body burden, representing long-term chromate exposure is best assessed by measuring chromium in whole blood or pre-shift urinary chromium at the beginning of the working week. Exceptionally high levels of chromium in blood (387-4160 nmol l-1) and urine (41-1250 nmol nmol-1 creatinine) as well as skin and nasal lesions, were discovered amongst the workforce at the strontium chromate plant. These contrasted with occupationally unexposed levels of less than 20 nmol l-1 and less than 1 nmol nmol-1 creatinine, respectively, and led to the continuation of the biological monitoring programme. At the same time, improved working practices and respiratory protection equipment were introduced. A steady elimination of chromium from whole blood with a half-life of approximately 24 days was found. This elimination rate was confirmed over a 14 day period when the workforce were completely removed from exposure. The study confirms the usefulness of biological monitoring in assessing the uptake of hexavalent chromium and control of exposure.