[Studies on relationship between exposure to low concentration of mixed benzene and lower quality of semen and very early fetal loss].

To study the effects of exposure to low concentration of mixed benzene on their semen quality and very early fetal loss (VEFL) in the occupational population. Environmental monitoring and biological monitoring were conducted in 126 employees exposed to mixed benzene and 60 unexposed ones selected from a large petrochemical corporation and a large chemical fiber corporation. Quality of semen in 70 male workers in the exposed group and 90 male internal controls and 132 male external controls were analyzed, and urinary beta-human chorionic gonadotropin (beta-hCG) was determined for 42 female exposed workers and 49 female internal controls and 118 external controls. 1. Exposure to mixed benzene mainly existed in low concentrations (0.7-27.0 mg/m3) in the petrochemical corporation, and urine concentration of t, t-MA in the workers correlated significantly to benzene concentration in ambient air of the workshops (r = 0.64, P = 0.03). 2. The sperm progression and motility in the exposed (1.97 +/- 0.63 and 0.55 +/- 0.16) and the internal control (1.97 +/- 0.69 and 0.55 +/- 0.17) groups were significantly (P < 0.05) lower than those in the external control group (2.56 +/- 0.61 and 0.60 +/- 0.13), however, the sperm abnormality rates in the exposed and internal control groups were significantly (P < 0.01) higher than those in the external control group, and the summary abnormality rate of sperm in the exposed group (85.71%) was higher than that in the internal (70.00%) and external control (76.51%) groups (P < 0.05). 3. The incidence rates of the VEFL in female workers and the cyclic occurrence of VEFL both in the exposed and internal control groups (10.42% and 9.60%) were higher than those in the external control group (5.09%), with statistical significance (P < 0.05). Exposure to low concentration of mixed benzene maybe correlated with the declined quality of semen and VEFL in occupational workers, and urinary t, t-MA and beta-hCG can be used as biomarkers of exposure and effect, respectively.