Objective To evaluate occupational benzene exposure levels by meta regression analysis.
Methods A bibliographic search of occupational benzene exposure in China was conducted across CNKI, WanFang, and PubMed databases from January 1, 1983 to September 30, 2017. The keywords for searching were benzene, workplace, concentration, and exposure in both English and Chinese. Overall, 118 articles were selected based on pre-determined inclusion and exclusion criteria. Linear mixed-effect meta regression models were developed to evaluate the trend of benzene exposure level in different sectors by SAS 9.3 software.
Results Based on the published data, the overall median concentration of short-term exposure (CSTEL) and time-weighted average (CTWA) of benzene in all industries from 1983 to 2014 were 6.26 mg/m3 and 1.87 mg/m3, respectively. The top three CSTEL medians were in furniture (26.63 mg/m3), leather, fur, feathers, and their products and shoes (leather and shoes thereafter) (15.99 mg/m3), and general equipment (7.98 mg/m3) manufacturing sectors. All the concentrations were higher than 10 mg/m3 before 2000 except 1998 and 2000. There were declines of 8%-31% per year in CSTEL in leather and shoes, furniture, petrochemical, chemicals, and rubber manufacturing sectors, as well as an increase of 46% per year in CTWA in petrochemical industry from 1983 to 2014 (P < 0.05).
Conclusion The benzene exposure levels in leather and shoes, furniture, chemicals, and rubber manufacturing sectors show declining trends based on literature reports.
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