基于生物监测指标评估的低浓度苯暴露职业健康风险

Assessment of health risk of occupationally low-level benzene exposure based on biological monitoring indicator

目的通过流行病学调查资料和苯接触生物标志物的检测资料,初步建立基于生物监测指标的低浓度苯暴露致癌风险评价方法。方法根据苯的流行病学调查资料,基于多阶模型推导出低浓度苯职业暴露下的致癌风险模型。利用贝叶斯线性回归和马尔科夫链蒙特卡洛方法,采用R语言、JARG软件包和水晶球软件建立苯空气浓度与苯代谢物浓度函数关系并进行不确定性分析,并利用尿中苯巯基尿酸(S-phenylmercapturic acid,S-PMA)和反-反式黏糠酸(trans,trans-muconic acid,tt-MA)的浓度预测苯的致癌风险。结果考虑适用低浓度苯暴露的情况,建立了二项式的多阶模型用于表征致癌风险。基于建立的致癌风险模型,我国现行的职业接触限值[空气中苯的时间加权平均容许浓度6 mg/m^(3),工作班后尿S-PMA浓度100μg/g(以Cr校正),班后尿tt-MA浓度3.0 mg/g(以Cr校正)]下的致癌风险分别为5.64×10^(-4)、2.31×10^(-4)、1.52×10^(-4),均高于美国环境保护署(EPA)和疾病预防控制中心(CDC)提出的职业人群致癌风险可接受水平(10^(-4))。结论利用苯的代谢产物预测致癌风险,显示在空气中苯浓度低于职业接触限值的情况下,苯的致癌影响仍然存在。需要采取工程控制及个体防护等措施,尽可能降低苯的致癌风险。目前我国苯职业接触限值存在尽可能降低的必要性。

Objective The cancer risk of occupationally low-level benzene exposure was assessed based on epidemiological survey data and biological monitoring biomarkers of benzene exposure.Methods Based on the epidemiological data of occupational benzene exposure,the cancer risk model of occupational exposure to low-level benzene was deduced with multistage method.The relationship between air benzene concentration and metabolite concentration and its uncertainty analysis were done based on Bayesian linear regression and Markov Chain Monte Carlo method using R language,JARG software package and Crystal Ball software.The urinary S-phenylmercapturic acid(S-PMA)and trans,trans-muconic acid(tt-MA)concentrations were used to assess the cancer risk of benzene exposure.Results Considering the low-level benzene exposure,a binomial multi-stage model was established to characterize the carcinogenic risk.The benzene exposure at level with current values of occupational exposure limits in China,including permissible concentration-time weighted average of benzene in air(6 mg/m^(3)),urinary S-PMA concentration(100μg/g Cr)and tt-MA concentration(3.0 mg/g Cr)after shift could cause the cancer risk 5.64×10^(-4),2.31×10^(-4)and 1.52×10^(-4),respectively,which were higher than the acceptable level 10^(-4)for occupational population proposed by US EPA and US CDC.Conclusions The cancer risk of benzene exposure at level with value of the national exposure limit was still relatively high,if benzene metabolites were used as indicator of exposure.In order to control the risk,engineering control and personal protection measures should be taken to reduce the exposure level as much as possible.In view of the risk acceptability,it is necessary to reduce the occupational exposure limit of benzene in China.