Sister-chromatid exchanges in lymphocytes from 12 chromium platers: a 5-year follow-up study

To detect the mutagenic effects of hexavalent chromium (Cr) in humans, sister-chromatid exchange (SCE) frequency in lymphocytes and urinary Cr was determined in 66 blood-urine paired samples from 12 male Cr-platers during 5 years (1984-1989). Multiple regression of SCE frequency on age, urinary Cr and smoking habits was analyzed in all 66 samples. Neither age (P = 0.204) nor urinary Cr (P = 0.056) was a significant predictor for SCE frequency. Although urinalysis revealed obvious exposure to Cr in the platers, exposure was unable to influence SCE frequency. Smoking habits were a highly significant (P less than 0.001) positive predictor for SCE frequency, and smoking of one cigarette per day was associated with an increase of 0.054 SCEs/cell in SCE frequency. SCE frequency significantly fluctuated from year to year in 3 subjects. The smoking habits of these 3 subjects did not change during the follow-up period. The results suggest that there are other unknown factors influencing SCE frequency in addition to smoking habits.