Brain R A, Anderson J C, Hanson M L
Syngenta Crop Protection, LLC, Greensboro, NC 27409, USA.
Department of Environment and Geography, University of Manitoba, Winnipeg, MB R3T 2N2, Canada.
Ecotoxicol Environ Saf. 2021 May 8;218:112303. doi: 10.1016/j.ecoenv.2021.112303.
Given the limited data available for estuarine/marine fish species and potential risk of being exposed to the herbicide atrazine, additional toxicity data regarding sensitive life-stages are needed. As such, this work sought to characterize: 1) the acute larval toxicity, and 2) early life-stage toxicity of technical atrazine in the model marine species sheepshead minnow (Cyprinodon variegatus). Atrazine was observed to be slightly to moderately toxic towards C. variegatus under acute conditions (as per U.S. EPA 2017 criteria). After 96 h exposure, mortality rates of 5%, 15%, 35%, and 90% were observed among fish exposed to atrazine at 4.6, 7.6, 13, and 22 mg a.i./L, respectively. Sub-lethal effects were observed among surviving fish exposed to > 3.2 mg a.i/L. The 96 h LC50 was 13 mg a.i./L and the NOEC was 3.2 mg a.i./L. In the 33 d early-life stage test, mean embryo survival rates in 0.15, 0.30, 0.57, 1.1, and 2.2 mg a.i./L treatments ranged from 71% to 79% and were not different from survival in the control (78%). Following 28 d post-hatch exposure (Day 33), mean larval survival ranged from 98% to 100% in all treatments and the control. Larval length and wet weight were the most sensitive indicators of the toxicity of atrazine to early life-stage sheepshead minnow. The NOEC for growth was 1.1 mg a.i./L and the LOEC was 2.2 mg a.i./L. Based on these, the MATC for atrazine to sheepshead minnow embryos and larvae was estimated to be 1.6 mg a.i./L. These results were consistent with previous investigations in sheepshead minnow and other marine fish species. Based on the results, atrazine would not be expected to pose unacceptable risks for sheepshead minnow early life-stages at environmentally relevant concentrations.
鉴于河口/海洋鱼类物种的可用数据有限，以及接触除草剂阿特拉津的潜在风险，需要有关敏感生命阶段的更多毒性数据。因此，这项工作旨在确定：1）阿特拉津原药对模式海洋物种红树鳉（Cyprinodon variegatus）的急性幼体毒性，以及2）早期生命阶段毒性。在急性条件下（根据美国环境保护局2017年标准），观察到阿特拉津对红树鳉有轻微至中度毒性。暴露96小时后，暴露于4.6、7.6、13和22毫克有效成分/升阿特拉津的鱼类死亡率分别为5%、15%、35%和90%。在暴露于大于3.2毫克有效成分/升阿特拉津的存活鱼类中观察到亚致死效应。96小时半数致死浓度为13毫克有效成分/升，无观察效应浓度为3.2毫克有效成分/升。在为期33天的早期生命阶段试验中，0.15、0.30、0.57、1.1和2.2毫克有效成分/升处理组的平均胚胎存活率在71%至79%之间，与对照组（78%）的存活率没有差异。孵化后28天暴露（第33天）后，所有处理组和对照组的平均幼体存活率在98%至100%之间。幼体长度和湿重是阿特拉津对早期生命阶段红树鳉毒性最敏感的指标。生长的无观察效应浓度为1.1毫克有效成分/升，最低观察效应浓度为2.2毫克有效成分/升。基于这些，阿特拉津对红树鳉胚胎和幼体的最大允许毒物浓度估计为1.6毫克有效成分/升。这些结果与之前对红树鳉和其他海洋鱼类物种的研究一致。根据结果，预计在环境相关浓度下，阿特拉津不会对红树鳉的早期生命阶段造成不可接受的风险。
