OBJECTIVETo explore the biological effective markers, we investigated DNA strand breaks in peripheral lymphocytes from occupational population with broad ranges of soluble chromate exposure.

METHODSWe conducted a cross-sectional study in the chromate exposed workers employed at a chromate factory in a district of Jinan, Shandong Province. The studied population contained 114 workers from different processes of the chromate plants, in addition, 30 farmers in the countryside about one hundred kilometers away from the factory, without exposure to chromate were matched with the exposed subjects by age, gender and smoking status being identified as a control group. Personal information on age, chromate exposure, medical history (including acute infection and medicine usage), smoking habit and alcohol consumption was obtained by questionnaire. DNA strand breaks in lymphocytes were detected by single-cell gel electrophoresis assay (comet assay) and the DNA damaged degree was evaluated by the score weighted by comet type. The air concentration of chromate was determined by individual sampling for 8 hours per day as shift work and chromium was assayed by atomic absorption spectrometry. The chromium content in the erythrocytes from peripheral blood was determined by graphite furnace atomic absorption spectrometry. The data were analyzed by SPSS10.0 software for statistical significance.

RESULTS(1) The results showed that the score for DNA strand breaks in lymphocytes were 54.52 +/- 23.51 in the exposed group, which was significantly higher than those in the control group (24.70 +/- 11.84) (P < 0.01). (2) The degree of DNA strand breaks in lymphocytes was increased in a dose-dependent manner ranging from 0 microg/m(3) to 106.00 microg/m(3). (3) Correlation analysis showed that there was a significant positive correlation between airborne chromate concentration and the degree of DNA strand break in lymphocytes (P < 0.01). (4) By multiple regression analysis, it was found that the airborne concentrations, chromium contents in red blood cells and smoking habits were factors which might affect the degree of DNA breaks.

CONCLUSIONOur findings suggest that DNA strand break in lymphocytes should be an effective biomarker for occupational chromate-exposed population and be applied in biological monitoring and health risk assessment for occupational chromate-exposed population.