基于生物可给性的道路交通颗粒物中典型有机污染物健康风险研究

The road traffic emissions have been regarded as one of the most significant contributors to air pollution in China. Road traffic-related particulate matters (RTPM) are complex mixtures consists of numerous harmful substances that exposed to densely populated urban areas, thus the health risk assessment of road traffic emissions has become a hot research topic in recent years. The bioaccessibility of pollutants is identified as an important parameter for refining exposure assessment. However, the studies on the risk assessment of the road traffic emissions are based on the total concentration of pollutants without consideration of their bioaccessibility, giving rise to overestimation of their exposure risk. This project aims to study the health risk of RTPM-bound organic pollutants based on their bioaccessibility. RTPM will be sampled from typical areas in North China. Then, physiologically based in vitro models will be developed to evaluate the bioaccessibility of typical organic pollutants like polycyclic aromatic hydrocarbons (PAHs) and benzothiazoles (BTHs), in the RTPM, and factors and mechanisms controlling the release of PAHs and BTHs in the artificial body fluids will also be investigated. Further, the health risk of the bioaccessible fraction of PAHs and BTHs in road traffic-related PM will be assessed by the health risk assessment models. The implementation of this project is expected to scientifically and accurately assess the health risks of toxic organic pollutants on the RTPM, and provide the management department with the theoretical and technical support for formulating emission standards of road traffic major pollutants.

道路交通污染严重影响我国大气环境质量，道路交通排放的颗粒物含有大量有害物质且对城市密集人群的暴露强度高，因而道路交通污染物的健康风险评价已成为近年来的研究热点。污染物的生物可给性是精细化暴露评估的重要参数，但目前对道路交通颗粒物中污染物的风险评价普遍以污染物的总浓度为依据，未考虑污染物的生物可给性，这就很可能高估了健康风险。本项目拟选取华北地区典型区域，采集道路交通颗粒物，利用基于人体生理学的体外模型评估其中典型有机污染物（多环芳烃PAHs和苯并噻唑及其衍生物BTHs）的生物可给性，并探索影响道路交通颗粒物中PAHs和BTHs在人工体液中释放的影响因素及机制。在此基础上，结合健康风险评价模型，评价道路交通颗粒物的健康风险。项目的实施，可望科学准确地评价道路交通颗粒物中典型毒害有机污染物的健康风险，为管理部门制定道路交通排放的主要污染物的排放标准提供理论依据和技术支持。

道路交通污染已严重影响我国大气环境质量，道路交通排放的颗粒物（RTPM）中含有大量有害物质，可以通过呼吸道、消化道和皮肤接触等途径暴露进入人体，对人体健康造成重大危害。准确测定RTPM中典型有机污染的生物有效性成为评价其人体健康风险的重要理论依据。本项目选取高速公路隧道和典型城市交通主干道，采集RTPM样品，定量分析了不同来源RTPM中典型有机污染物（多环芳烃PAHs和苯并噻唑及其衍生物BTHs）的污染水平和分布特征；优化了基于人体生理学的模拟人体呼吸道、胃肠道和皮肤体外实验方法，研究不同来源道路交通颗粒物中PAHs和BTHs的生物可给性及其影响因素，并基于生物可给性评估人体暴露健康风险。其主要成果包括：1）隧道和主干道颗粒物中以4-6环PAHs为主，说明其主要来源于机动车的尾气排放和轮胎磨损等非尾气管排放，隧道颗粒物中PAHs和BTHs浓度远高于主干道，PAHs浓度与颗粒物中有机碳和炭黑呈正相关关系；2）以RTPM为研究基质，优化了体外模型的关键参数，包括呼吸道体外模型的肺表面活性剂（DPPC）和Tenax“吸附池”添加量，胃肠体外模型的胆汁盐浓度以及合成汗液中皮脂添加量，考虑人体生理学实际情况，确立与人体情况相近的模型参数；3）不同来源RTPM样品中PAHs和BTHs的生物可给性存在较大差异，不同化合物的生物可给性也存在很大差异，说明生物可给性受到化合物本身理化性质（如logKOW和水溶解性等）和颗粒物性质（颗粒物来源、粒径、有机碳和炭黑含量等）等因素的影响；4）基于生物可给性，本研究评估了RTPM中PAHs和BTHs人体健康风险，发现RTPM中BTHs的健康风险可忽略，PAHs经口摄入的健康风险也可忽略，经吸入途径暴露隧道PM2.5具有轻微的潜在致癌风险，而皮肤接触轮胎磨损颗粒物具有较大的致癌风险，本研究为准确评价大气颗粒物中有毒物质暴露健康风险提供科学参考。