Prometryn (PRO) is frequently detected in shellfish of international trade among triazine herbicides because of its wide application in agriculture and aquaculture worldwide. Nevertheless, the variations of PRO remain unclear in aquatic organisms, which affect the accuracy of their food safety risk assessment. In the present study, the tissue-specific accumulation, biotransformation, and potential metabolic pathway of PRO were reported in oyster species Crassostrea gigas for the first time. The experiments were conducted through semi-static seawater exposure with low and high concentrations of PRO (at nominal concentrations of 10 and 100 μg/L) via daily renewal over 22 days, followed by 16 days of depuration in clean seawater. The characterization of prometryn in oysters was then evaluated through the bioaccumulation behavior, elimination pathway and metabolic transformation, comparing with other organisms. The digestive gland and gonad were found to be the main target organs during uptake. In addition, the highest bioconcentration factor of 67.4 ± 4.1 was observed when exposed to low concentration. The level of PRO in oyster tissues rapidly decreased within 1 day during depuration, with an elimination rate of >90 % for the gill. Moreover, four metabolites of PRO were identified in oyster samples of exposed groups, including HP, DDIHP, DIP, and DIHP, in which HP was the major metabolite. Considering the mass percentage of hydroxylated metabolites higher than 90 % in oyster samples, PRO poses a larger threat to aquatic organisms than rat. Finally, the biotransformation pathway of PRO in C. gigas was proposed, the major metabolic process of which was hydroxylation along with N-dealkylation. Meanwhile, the newly discovered biotransformation of PRO in oyster indicates the importance of monitoring environmental levels of PRO in cultured shellfish, to prevent possible ecotoxicological effects as well as to ensure the safety of aquatic products.

扑草净（PRO）因其在全球农业和水产养殖中的广泛应用，在三嗪类除草剂国际贸易的贝类中经常被检测到。然而，水生生物中PRO的变化仍不清楚，这影响了其食品安全风险评估的准确性。本研究首次报道了巨牡蛎中PRO的组织特异性积累、生物转化和潜在代谢途径。实验通过半静态海水暴露于低浓度和高浓度的 PRO（标称浓度为 10 和 100 μg/L）进行，每天更新 22 天，然后在清洁海水中净化 16 天。然后通过生物富集行为、消除途径和代谢转化来评价扑草净在牡蛎中的特性，并与其他生物体进行比较。发现消化腺和性腺是摄取过程中的主要靶器官。此外，当暴露于低浓度时，观察到最高的生物浓缩因子为 67.4 ± 4.1。牡蛎组织中的PRO水平在净化过程中1天内迅速下降，鳃的消除率>90%。此外，在暴露组的牡蛎样品中还鉴定出了四种PRO代谢物，包括HP、DDIHP、DIP和DIHP，其中HP是主要代谢物。考虑到牡蛎样品中羟基化代谢物的质量百分比高于90%，PRO对水生生物的威胁大于大鼠。最后提出了C. gigas中PRO的生物转化途径，其主要代谢过程是羟基化和N-脱烷基化。同时，新发现的PRO在牡蛎中的生物转化表明监测养殖贝类中PRO的环境水平的重要性，以防止可能的生态毒理学效应并确保水产品的安全。