水产品相对生物利用度及在镉暴露风险评估中的应用

Relative bioavailability of cadmium in aquatic products and its application on the cadmium exposure risk assessment

【目的】了解不同种类水产品镉的相对生物利用度(RBA)值,进一步优化和验证镉的生理毒代谢动力学(PBTK)模型,优化食品安全风险评估中定量评估的内外暴露关联机制,并推导出镉的暂定每日耐受摄入量(PTDI)值。【方法】使用4周龄balb/c雌性小鼠测定不同水产品中镉的RBA,进一步结合上海市居民镉的内外暴露数据,考虑性别及镉在不同食品中的RBA的差异,使用近似贝叶斯-马尔科夫链-蒙特卡洛算法(ABC-MCMC algorithm)优化镉代谢的PBTK模型,计算出PTDI。【结果】除扇贝和鱿鱼外,水产品样品的RBA均<1,说明水产品中镉的吸收率低于镉的氯化物形式。鱿鱼、扇贝RBA较高,可能由于其中内脏镉的存在形式有利于镉的吸收,以及其本身镉浓度较高。炒制(温度<160℃)可降低镉的吸收,而炸制(温度>160℃)或增加镉的吸收。优化后的模型参数收敛性良好且模型能根据镉的外暴露量对尿镉进行合理估计,根据优化后的单腔室模型推导出以体重计的PTDI值为0.4664μg·(kg·d)^(-1)。【结论】不同食物中镉的RBA差异较大,除鱿鱼和扇贝外,RBA均<1,烹调加工会影响食物的RBA。对于PBTK模型的构建,不仅考虑了性别差异对镉代谢的影响,还将得出的RBA数据纳入模型对吸收率相关系数进行优化调整。相较于未经RBA调整的模型,调整后的模型对尿镉的预测能力增强,为食品安全风险评估提供了更加准确的新方法。

[Objective]To understand the relative bioavailability(RBA)of cadmium in different aquatic products.Based on the consideration of the gender differences and the relative bioavailability of cadmium in different foods,the physiologically based toxicokinetic(PBTK)model of cadmium was further optimized and verified.The correlation between internal and external exposure in quantitative risk assessment of food safety was optimized,and the provisional tolerable daily intake(PTDI)value of cadmium was derived.[Methods]The relative bioavailability of cadmium in different aquatic products was determined in four-week-old Balb/c female mice.The PBTK model of cadmium metabolism was optimized by ABC-MCMC method using combined internal and external exposure data of cadmium in Shanghai residents,and the PTDI was calculated accordingly.[Results]Except for scallops and squid,the RBA of aquatic samples was less than 1,indicating that the absorption rate of cadmium in aquatic products was lower than that of cadmium chloride.The higher RBA of squid and scallop may be due to the presence of cadmium in the visceral organs,which is conducive to cadmium absorption and its higher concentration of cadmium.Frying at the temperature less than 160℃reduced cadmium absorption but may increase cadmium absorption at the temperature greater than 160℃.The optimized model parameters converged well and the model could reasonably estimate urinary cadmium level according to the external exposure of cadmium.The PTDI value was 0.4664μg·(kg·day)^(-1)according to the optimized single-chamber model.[Conclusion]The relative bioavailability of cadmium in different foods varies greatly,except for squid and scallops,RBA is less than 1,and cooking processing will affect the RBA of food.The construction of the PBTK model did not only consider the effects of gender differences on cadmium metabolism,but also included the relative bioavailability data to optimize and adjust the correlation coefficient of absorption rate.Compared with the model without RBA adjustment,the adjusted model has enhanced the ability to predict urinary cadmium level,which provides a new,more accurate method for the risk assessment of food safety.