HEMATOTOXICITY AMONG CHINESE WORKERS HEAVILY EXPOSED TO BENZENE

Benzene is a well-established hematotoxin. However, reports of its eff ects on specific blood cells have been somewhat inconsistent and the r elative toxicity of benzene metabolites on peripheral blood cells in h umans has not been evaluated. We compared hematologic outcomes in a cr oss-sectional study of 44 workers heavily exposed to benzene (median: 31 parts permillion [ppm] as an 8-hr time-weighted average [TWA] and 4 4 age and gender-matched unexposed controls from Shanghai, China. All hematologic parameters (total white blood cells [WBC], absolute lympho cyte count, platelets, red blood cells, and hematocrit) were decreased among exposed workers compared to controls, with the exception of the red blood cell mean corpuscular volume (MCV), which was higher among exposed subjects. In a subgroup of workers who were not exposed to mor e than 31 ppm benzene on any of 5 sampling days (n = 11, median 8 hr T WA = 7.6 ppm, range = 1-20 ppm), only the absolute lymphocyte count wa s significantly different between exposed workers (mean [sd] 1.6 [0.4] x 10(3) mu L) and controls (1.9 [0.4] x 10(3) mu L, p = 0.03). Among exposed subjects, a dose-response relationship with various measures o f current benzene exposure (i.e., personal air monitoring, benzene met abolites in urine) was present only for the total WBC count, the absol ute lymphocyte count, and the MCV. Correlations between benzene metabo lites and hematologic parameters were generally similar, although hydr oquinone was somewhat more strongly associated with a decrease in the absolute lymphocyte count, and catechol was more strongly associated w ith an increase in MCV. Morphologic review of peripheral blood slides demonstrated and excess of red blood cell abnormalities (i.e., stomato cytes and target cells) only in the most heavily exposed workers, with no differences in granulocyte, lymphocyte, or platelet morphology not ed. Although benzene can affect all the major peripheral blood element s, our results support the use of the absolute lymphocyte count as the most sensitive indicator of benzene-induced hematotoxicity. (C) 1995 Wiley-Liss, Inc.