Use of molecular epidemiological techniques in a pilot study on workers exposed to chromium

Objectives - Molecular epidemiological techniques, capable of detecting damage to DNA, were used to see if such damage occurred in the lymphocytes of a group of workers exposed to chromium. The two aims of this pilot study were to see if these new techniques might make useful biological monitoring tools for workers exposed to chromium and also, to help assess whether the current occupational exposure limit for chromium (VI) was sufficiently protective in this specific working situation. Methods - Volunteer groups of 10 workers exposed to chromium and 10 nonexposed workers provided urine and blood samples towards the end of the working week. Chromium concentrations were measured in whole blood, plasma, lymphocytes, and urine. Lymphocytes were used to examine two forms of DNA damage in the two groups; these were the level of DNA strand breakage and, the production of 8-hydroxydeoxyguanosine. Results - Chromium concentration in whole blood, plasma, and urine of workers exposed to chromium was significantly raised (P < 0.01 compared with non-exposed controls, but in isolated lymphocytes, there was only a modest but significant (P < 0.05) increase in chromium in the group exposed to chromium. There was no difference in the levels of DNH strand breaks or 8-hydroxydeoxyguanosine between the groups. Air monitoring for chromium was not undertaken but current levels for the group exposed to chromium were reported to be around 0.01 mg/m³, which is 20% of the current United Kingdom occupational exposure limit. Conclusion - We were unable to detect any damage in lymphocytic DNA due to exposure to chromium. This may have been due to the low chromium exposure (20% of the United Kingdom occupational exposure limit), the ability of plasma to detoxify chromium (VI) to chromium III before it reached the lymphocytes, or perhaps the insensitivity of the molecular techniques used. It is now important to test these and other such techniques on groups exposed to levels closer to the United Kingdom occupational exposure limit.