Objective: 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.
Methods: 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.
Results: 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).
Conclusions: 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.