大米中无机砷风险评估方法学研究

Study on methodology for risk assessment of inorganic arsenic in rice

目的研究风险评估在大米中无机砷健康风险防控的应用。方法以评估中国东南沿海A县县域大米中的无机砷及其干预或控制措施对当地人群的致癌风险的影响为例,将大米中无机砷的检测数据、消费量调查数据、生物利用率和剂量-反应关系模型相结合,使用@RISK 7.5对不同情景下样品来源地一般人群的膀胱癌和肺癌风险进行概率评估。结果国标限量和正常消费情景下大米来源的无机砷暴露导致的25年后膀胱癌和肺癌年新发病例数约为0.045例/10万人,在25年后一切原因导致的年新发病例数(约209.2例/10万人)中几乎可以忽略不计(约占0.021 5%),由此造成的平均预期寿命损失约为0.000 529岁/0.193 1 d。改变国标限量和/或消费结构的再干预或控制措施对风险的影响很小,即使假设无机砷限量和大米消费量均降为原来的1/2,肺癌的发病率也仅下降2.16%。结论研究显示改变消费结构和/或国标限量对降低大米中无机砷的风险意义不大,当前的假设情景也存在较大的局限性和不确定性,但本研究为整合、评价和应用新的公共卫生科学信息提供了一个方法框架。

Objective To study the application of risk assessment in the prevention and control of health risk of inorganic arsenic in rice. Methods Taking the health effect assessment of inorganic arsenic from rice and the existing possible interventions or control measures on local population in A county as an example. The detection data, consumption survey data, bioavailability and dose-response relationship model were combined, and @RISK 7.5 was used for probability assessment of the risk of bladder cancer and lung cancer in the general population in different scenarios. Results In the normal limit and consumption scenario, the number of new bladder and lung cancer cases after 25 years is 0.045 cases per 10~5 population per year. This was almost negligible(about 0.021 5%) compared with new cases by all causes after 25 years(about 209.2 cases per 10~5 population per year). The resulting loss in average life expectancy was approximately 0.000 529 years/0.193 1 days. Acceptable levels and the possible reintervention or control measures had little impact on the risk. Even assuming that both the inorganic arsenic limit and rice consumption were reduced by half, the incidence of lung cancer only fell by 2.16%. Conclusion The study showed that changing the consumption structure and/or national standard limits had little significance to reduce the risk of inorganic arsenic in rice, and the current hypothetical scenario also had great limitations and uncertainties, but provided a framework for integration, evaluation and application of new information in the public health.