Assessment of complete blood count variations among workers exposed to low levels of benzene

The effect of benzene on white blood cell and red blood cell counts, hemoglobin level, mean corpuscular volume (MCV), and platelet count was investigated among workers in a small petroleum company. The investigated cohort consisted of 105 workers exposed to low levels of benzene between 1967 and 1994. The average level of benzene exposure per year ranged between 0.14 parts per million and 2.08 parts per million (8-hour time-weighted average). The mean complete blood count (CBC) demonstrated values within normal ranges. With the exception of white blood cells, all other CBC values were significantly reduced during the follow-up period. Length of employment was significantly related to the changes in MCV and platelet counts. The reductions in MCV were significant only among workers who had been employed for more than 10 years at this particular company. The findings of this study suggest that low levels of benzene may affect CBC values. CBC values may serve as a useful tool for biological monitoring for workers with low-level benzene exposure.