[Chromium content in erythrocytes serving as the exposure biomarker for workers exposed to soluble chromate]

To explore biological exposure markers, we investigated the chromium content in peripheral erythrocytes from occupational population with broad ranges of soluble chromate exposure, as the candidate biomarker may provide the scientific evidence for health risk assessment in occupational chromate-exposed population.

A cross-sectional study was conducted in chromate exposed workers employed at a chromate factory in a district of Jinan city, Shandong Province. The studied population contained 114 workers from different processes of the chromate plants, which included 74 males and 40 females, with an age range from 25 to 52 years old, averaging at (35.83 +/- 6.14) years old; the length of service was ranging from 1 year to 37 years, an average of (14.20 +/- 6.77) years. In addition, 30 farmers in the countryside one hundred kilometers away from the factory, without exposure to chromate matched with exposed subjects by age, gender and smoking status were identified as a control group, which included 22 men and 8 women, with age ranging from 25 years old to 47 years old, having an average age of (36.13 +/- 6.17) years old. Personal information on age, chromate exposure, medical history, smoking habit and alcohol consumption was obtained at an interview. The air concentration of personal exposure 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 potential plasma reduction capacity was determined by dibenzene anthracoamid dihydrazide spectrophotometry. The content of total vitamin C and reductive ascorbic acid were determined by 2, 4-dinitrobenzene hydrazine. The data were analyzed by SPSS10.0 software for statistical significance.

(1) The results showed that the chromium levels in erythrocytes in the exposed group [(15.79 +/- 31.01) microg/L] were significantly higher than those in the control group [(3.21 +/- 2.20) microg/L] (P < 0.01). (2) There existed a dose-response relationship between the personal airborne chromate concentration and the chromium content in erythrocytes. As airborne chromate concentration lowered to 106.00 microg/m(3), the chromium content in erythrocytes increased, depending on the air concentration of chromate. (3) Correlation analysis showed that there was a significant positive correlation between airborne chromate concentration and the chromium content in erythrocytes (P < 0.01). (4) In multiple regression analysis, it was found that the potential plasma reduction capacity and reductive ascorbic acid may be a good indicator for oxidative stress produced by chromate exposure and be used to evaluate the effects on intracellular uptake of chromium (VI).

Our findings suggested that the chromium content in erythrocytes should be used as an effective exposed biomarker in the risk assessment for occupational chromate-exposure.