典型酚类内分泌干扰物鱼体代谢机制及毒代动力学模拟研究

The discharge of domestic sewage and industrial wastewater leads to the wide detection of phenolic endocrine disrupting chemicals (EDCs), including nonylphenol, bisphenol A and triclosan, in receiving aquatic environment. Phenolic EDCs having a phenolic hydroxyl group with strong activity, which usually has high biotransformation ability and metabolism efficiency in organisms. Previous studies mostly focused on the bioaccumulation and ecological toxicity, while the knowledge on the metabolites and metabolism pathway of phenolic EDCs is lacking. Hence, it is difficult to fully assess their ecological and human health risks. Nonylphenol, bisphenol A and triclosan are selected as target compounds. The flow-through aquatic exposure systems are used to simulating the exposure of rare minnow (Gobiocypris rarus) to phenolic EDCs at environmentally relevant concentrations under laboratory conditions, and the metabolism and toxicokinetics in in fish tissues are evaluated. The biotransformation products of phenolic EDCs are identified using high resolution mass spectrometer. The fish tissue disposition and bioaccumulation mechanism of the parents and metabolites are evaluated. The activity of enzyme for the phases I and II metabolism are analyzed, and in vitro method of fish liver microsomes exposed to target compounds are carried out. The metabolic pathway of phenolic EDCs in liver and other tissues are proposed. Collecting and determining the key physiological and biochemical parameters, the fish physiology based toxicokinetic model are established, and the model will be used to predict the accumulation level of phenolic EDCs and the metabolites in fish. The results will contribute to providing the scientific basis for ecological and human health risk assessment, and hence supporting for the control of phenolic EDCs and chemicals with similar structures.

生活污水和工业废水的排放，导致受纳水体中广泛检出壬基酚、双酚A和三氯生等酚类内分泌干扰物，并在水生生物体内富集。酚类内分泌干扰物具有活性较强的酚羟基，使其在生物体内具有较高的转化和代谢效率，但前期研究多集中于生物富集和毒理效应研究，缺乏对转化产物和代谢途径的认识，因此难以全面评价其生态和人体健康风险。本项目以壬基酚、双酚A和三氯生为目标物，采用实验室恒流暴露系统，模拟稀有鮈鲫暴露于环境相关浓度目标物的情景，研究其鱼体代谢及毒代动力学过程。利用高分辨质谱鉴定其生物转化产物，明确母体及代谢物的鱼体组织分配及蓄积机制；测定相关代谢酶活性，并结合污染物在鱼肝微粒体的体外暴露实验，推断酚类内分泌干扰物在肝脏等组织的代谢途径；厘定关键生理生化参数，建立鱼体生理毒代动力学模型，预测鱼体中酚类内分泌干扰物及代谢物的蓄积水平，为此类物质的风险评价和化学品管控提供科学依据。

生活污水和工业废水排放导致受纳水体中广泛检出酚类内分泌干扰物和药物，并在水生生物体内富集。酚类内分泌干扰物和药物在生物体内具有较高的转化和代谢效率，但前期研究多集中于生物富集和毒理效应研究，缺乏对其转化产物、代谢途径和积累水平预测等的认识，因此难以全面评价其生态和人体健康风险。本研究针对酚类内分泌干扰物和药物，探究其在鱼体中的积累、消除规律，推断其代谢途径与重要生理生化参数，并构建鱼体生理毒代动力学模型，预测鱼体中酚类内分泌干扰物、药物及其代谢物的蓄积水平，为此类新污染物的风险评价和化学品管控提供科学依据。实验室与野外监测结果表明，化合物均容易在肝脏和胆汁中富集和代谢。实验室条件下三氯生在鱼肠道中生物富集水平高达3402ng/g，氟西汀和舍曲林在脾脏生物富集最高分别达到459和579ng/g。此外，肾脏和胃也展现出很高生物富集能力。根据吸收和消除动力学，大多数情况下目标化合物能够以相对较快的速率积累和消除。从毒代动力学预测生物积累因子（BCFk）与实测的BCF相一致，可以很好地预测目标化合物在鱼类中积累情况。本研究还探究了酚类内分泌干扰物在草鱼、鲤鱼、罗非鱼和稀有鮈鲫肝微粒体中的体外代谢及其关键代谢酶。结果表明，四种目标化合物在所有实验所选鱼体肝脏中均能进行代谢。对于BPA来说，在四种鱼体中的体外固有清除率按大小排序为：草鱼＞罗非鱼~稀有鮈鲫＞鲤鱼，CYP1A和CYP3A4在肝脏中对BPA代谢起到了主要作用。最后，建立了包含酚类内分泌干扰物代谢的鱼体生理毒代动力学（PBTK-MT）模型，与传统非代谢生理毒代动力学模型相比，加强了对肝脏代谢的预测。结果表明，通过校准肝脏分配系数有效地抵消了传统计算方法造成的模型预测值低估问题，PBTK-MT模型对三种目标酚类内分泌干扰物及其代谢拟合结果与实验测值吻合很好，表明该模型具有良好的预测性能（R2>0.85），为快速监测生物体中污染物的浓度水平提供了一种新思路。