[Study on the health effects of occupational exposure to low concentrations of benzene].

Objective: The main purpose of this study was to ascertain whether (or not) exposure to benzene, toluene, xylene and ethylbenzene (BTXE) , under normal working conditions, was associated with any health effects. Methods: From January to December 2014, the workplaces concentrations of BTXE were measured of 71 enterprises in Suzhou Industrial Park. Occupational health examination were investigated on 764 employees who exposed to BTXE, as well as 4409 employees of the corresponding enterprises who unexposed to BTXE, and analyzed the data of the two groups. Results: A total of 6 monitoring sites in 3 enterprises BTXE concentrations excess of the standards, the unexposed group was under the limit of detection. The means of red blood cell count, hemoglobin, hematocrit, intermediate cell count and percentage of intermediate cells were significantly higher in exposed group than in unexposed group (P<0.05) . Conversely, platelet count was significantly lower in exposed group than in unexposed group (P<0.05) . The proportion of red blood cell volume, lymphocyte count and percentage of intermediate cells were significantly lower in exposed group than in unexposed group (P<0.05) . Both means and proportion of glutamic pyruvic transaminase and urea nitrogen were significantly higher in exposed group than in unexposed group (P<0.05) . The positive rate of protein, urine, urine red blood cell were significantly higher in exposed group than in unexposed group (P<0.05) . The abnormal rate of electrocardiogram, liver and kidney B scan were significantly higher in exposed group than in unexposed group (P<0.05) . Multivariate logistic regression analysis revealed that percentage of intermediate cells increased, urea nitrogen increased, urine protein positived, urine red blood cells positived in exposed group the OR values were 1.689, 3.291, 3.163 and 1.743 (P<0.05) . Conclusion: Occupational exposure to low concentrations of BTXE had a certain impact on the blood system and liver and kidney function of the employees, occupational health surveillance for such people should be strengthened.