Qi Su Z, Chen Xiao F, Liu Yong, Jiang Jia Z, Wang Cheng J
a Key Laboratory of Pesticide Chemistry & Application Technology, Ministry of Agriculture, College of Science , China Agricultural University , Beijing , P. R. China.
J Environ Sci Health B. 2015;50(7):456-62. doi: 10.1080/03601234.2015.1018756.
Tebuconazole is a chiral triazole fungicide used as raceme in a variety of agricultural applications. Earlier studies showed that tebuconazole is toxic to many non-target aquatic organisms but relative data for tebuconazole enantiomers are lacking. Thus, goal of this study was to evaluate and compare the toxicity of rac- and S-tebuconazole with Daphnia magna at both acute and chronic levels according to Organization for Economic Cooperation and Development (OECD) guidelines 202 and 211 respectively, to provide some guidelines for optimizing chiral pesticides application and management. The exposure concentrations were 0.1, 0.5, 1, 2, 4, 8, 10 mg L(-1) for both rac- and S-tebuconazole and their 48-h EC(50) values to D. magna were 3.53 (3.32-3.78) and 2.74 (2.33-3.10) mg L(-1) respectively, indicating that these both are medium toxic to D. magna with no significant toxicity difference at acute level. In chronic test, <24-h old D. magna were exposed to 0.01, 0.05, 0.10, 0.20, and 0.40 mg L(-1) of rac- and S-tebuconazole with one blank and one solvent control for 21 days according to OECD guideline 211. Four developmental (molting rate, days to the 1st and 3rd brood, and body length) and five reproductive (size of the 1st and 3rd brood, number of broods, and number of neonates) parameters for each D. magna were determined. Results showed that both rac- and S-tebuconazole significantly reduced the reproduction and impacted the development of D. magna at concentrations of 0.05 mg L(-1) or higher. Furthermore, S-tebuconazole was more toxic than raceme, and the difference between effects on the same parameters induced by rac- and S-tebuconazole was statistically significant. These results demonstrated that the chronic toxicity of S-tebuconazole might be underestimated in general use, and further studies should focus more on the biological behaviors of enantiomers and not just the raceme of tebuconazole and other chiral pesticides in the environment.
戊唑醇是一种手性三唑类杀菌剂，在各种农业应用中以消旋体形式使用。早期研究表明，戊唑醇对许多非靶标水生生物有毒，但缺乏戊唑醇对映体的相关数据。因此，本研究的目的是分别根据经济合作与发展组织（OECD）准则202和211，评估和比较消旋戊唑醇和S-戊唑醇对大型溞的急性和慢性毒性，为优化手性农药的应用和管理提供一些指导方针。消旋戊唑醇和S-戊唑醇的暴露浓度均为0.1、0.5、1、2、4、8、10 mg L(-1)，它们对大型溞的48小时半数有效浓度（EC(50)）值分别为3.53（3.32 - 3.78）和2.74（2.33 - 3.10）mg L(-1)，表明二者对大型溞均为中等毒性，在急性水平上无显著毒性差异。在慢性试验中，根据OECD准则2l1，将小于24小时龄的大型溞暴露于0.01、0.05、0.10、0.20和0.40 mg L(-1)的消旋戊唑醇和S-戊唑醇中，设置一个空白对照和一个溶剂对照，持续21天。测定了每只大型溞的四个发育参数（蜕皮率、首次和第三次产卵天数以及体长）和五个生殖参数（首次和第三次产卵量、产卵次数以及幼体数量）。结果表明，消旋戊唑醇和S-戊唑醇在浓度为0.05 mg L(-1)或更高时，均显著降低了大型溞的繁殖能力并影响其发育。此外，S-戊唑醇比消旋体毒性更大，消旋戊唑醇和S-戊唑醇对相同参数的影响差异具有统计学意义。这些结果表明，在一般使用中，S-戊唑醇的慢性毒性可能被低估，未来的研究应更多地关注对映体的生物学行为，而不仅仅是戊唑醇和其他手性农药在环境中的消旋体。
