Assessment of complete blood count variations among workers exposed to lowlevels of benzene

The effect of benzene on white blood cell and red blood cell counts, hemogl obin level, mean corpuscular volume (MCV) and platelet count was investigat ed among workers in a small petroleum company. The investigated cohort cons isted 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. W ith the exception of white blood cells, all other CBC values were significa ntly reduced during the follow-up period. Length of employment was signific antly 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 gf this study suggest th at low levels of benzene may affect CBC values, CBC values may serve as a u seful tool for biological monitoring for workers with low-level benzene exp osure.