National Exposure Research Laboratory, US Environmental Protection Agency, Research Triangle Park, North Carolina, USA.
Region 9, US Environmental Protection Agency, San Francisco, California, USA.
Environ Toxicol Chem. 2018 Jan;37(1):99-106. doi: 10.1002/etc.3938. Epub 2017 Nov 2.
Some current-use pesticides are chiral and have nonsuperimposable mirror images called enantiomers that exhibit identical physical-chemical properties but can behave differently when in contact with other chiral molecules (e.g., regarding degradation and uptake). These differences can result in variations in enantiomer presence in the environment and potentially change the toxicity of pesticide residues. Several current-use chiral pesticides are applied in urban and agricultural areas, with increased potential to enter watersheds and adversely affect aquatic organisms. The present study describes a stereoselective analytical method for the current-use pesticides fipronil, cis-bifenthrin, cis-permethrin, cypermethrin, and cyfluthrin. We show use of the method by characterizing enantiomer fractions in environmental sample extracts (sediment and water), and laboratory-dosed fish and concrete extracts previously collected by California organizations. Enantiomer fractions for most environmental samples are the same as racemic standards (equal amounts of enantiomers, enantiomer fraction = 0.5) and therefore are not expected to differ in toxicity from racemic mixtures typically tested. In laboratory-derived samples, enantiomer fractions are more frequently nonracemic and favor the less toxic enantiomer; permethrin enantiomer fractions range from 0.094 to 0.391 in one type of concrete runoff and enantiomer fractions of bifenthrin in dosed fish range from 0.378 to 0.499. We use enantiomer fractions as a screening tool to understand environmental exposure and explore ways this uncommon measurement could be used to better understand toxicity and risk. Environ Toxicol Chem 2018;37:99-106. Published 2017 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.
一些现用农药具有手性，它们的镜像不能完全重叠，被称为对映异构体，这些对映异构体具有相同的物理化学性质，但与其他手性分子（如降解和吸收）接触时可能会表现出不同的行为。这些差异可能导致对映体在环境中的存在发生变化，并可能改变农药残留的毒性。一些现用的手性农药被应用于城市和农业地区，增加了进入流域并对水生生物产生不利影响的可能性。本研究描述了一种用于当前使用的农药氟虫腈、顺式氯菊酯、顺式氯氰菊酯、氯菊酯和氯氟氰菊酯的立体选择性分析方法。我们通过对环境样品提取物（沉积物和水）和加利福尼亚组织先前收集的实验室处理过的鱼类和混凝土提取物中的对映体分数进行特征描述，展示了该方法的用途。大多数环境样品的对映体分数与外消旋标准品相同（对映体等量，对映体分数=0.5），因此预计不会与通常测试的外消旋混合物在毒性上有所不同。在实验室衍生的样品中，对映体分数更频繁地是非外消旋的，并且有利于毒性较低的对映体；在一种类型的混凝土径流中，氯菊酯的对映体分数范围为 0.094 至 0.391，而在投毒鱼类中，氯菊酯的对映体分数范围为 0.378 至 0.499。我们将对映体分数用作筛选工具来了解环境暴露情况，并探索这种不常见的测量方法如何用于更好地了解毒性和风险。环境毒理化学 2018；37：99-106。2017 年 Wiley 期刊出版公司代表 SETAC 出版。本文是美国政府的一项工作，因此在美国属于公有领域。
