Sister chromatid exchange in pathology staff occupationally exposed to formaldehyde

Sister chromatid exchange (SCE) was measured in peripheral lymphocytes of 90 workers from 14 hospital pathology departments in Israel who were occupationally exposed to formaldehyde (FA) and of 52 unexposed workers from the administrative section of the same hospitals. The mean exposure period to FA was 15.4 years (range 1-39). The results of SCEs are expressed in two variables: (a) mean number of SCEs per chromosome and (b) proportion of high frequency cells (cells with more than eight SCEs). A high correlation was found between these two variables. The adjusted means of both SCEs variables were significantly higher among the exposed compared with that of the unexposed group (P<0.01). Adjustment was made for age, sex, smoking habits, education workers and origin. Evaluation of the influence of years of exposure on the frequency of SCEs showed that the two variables of SCEs were higher among those who were exposed to FA for 15 or more than among those with less than 15 years of exposure. Concerning levels of exposure, both variables of SCEs were the same in the low and in the high levels of exposure sub-groups. However, among the smokers, both variables of SCEs were higher in the high exposure sub-group than in the low exposure sub-group. Our finding of a significant increase of SCEs frequency in peripheral lymphocytes in pathology staff indicates a potential cytogenetic hazard due to FA exposure. We conclude that our data indicate that FA is mutagenic to humans.