Biomonitoring of two types of chromium exposure in an electroplating shop.

OBJECTIVES

This study is concerned with two specific chromium (Cr) exposure situations at a hard-process electroplating company. Its aims are to define variations in urinary Cr concentration and to clarify their exposure relationships.

METHODS

Airborne chromium exposure and urinary excretion were measured for a-one week period. The majority of the exposed population was divided into two groups distinguishing chromium plating and polishing functions. Analysis of airborne Cr distinguished water soluble Cr(VI), water total soluble Cr and water insoluble Cr. Volunteers provided 6-7 urine samples per day for a monitoring period of 7 days.

RESULTS

Differences between the two groups appear in relation to the type of exposure. Low concentration water soluble Cr(VI) (5.3 microg/m3 maximum) in electroplating shops is practically undetected in other workshops. Water insoluble Cr present in low concentration in electroplating exceeds 1 mg/m3 in polishing shops. Total soluble Cr concentrations are similar in these two activities (3-10 microg/m3). In polishing, 0.4% of the Cr aerosol comprises soluble Cr. Urinary Cr varied according to a 24 h cycle in similar manner in both groups throughout the monitoring week. Minimum values (3-10 microg/g crea) occurred when starting a work shift, following by a rapid rise as soon as exposure commenced, whilst maximum values (12-30 microg/g crea) were recorded towards the end of the work shift.

CONCLUSIONS

Although uncorrelated with soluble Cr(VI), urinary Cr (24 h) is effectively related to the soluble fraction of airborne chromium. In the case of chromium electroplating, correspondence between exposure and excretion appears to be governed by relationships different to those emerging from stainless steel welding, from which current biological limit values have been derived.