Programa de Seguridad Química, Instituto de Ciencias Ambientales y Salud (ICAS), Fundación PROSAMA, Paysandú 752, (1405) Buenos Aires, Argentina.
Environ Toxicol. 2011 Aug;26(4):373-81. doi: 10.1002/tox.20564. Epub 2010 Jan 28.
The acute and short term chronic toxicity of both the herbicide butyl ester of 2,4-Dichlorophenoxyacetic acid (2,4-D) and a commercial formulation (CF) were evaluated on Rhinella (= Bufo) arenarum embryos at different developmental stages. Adverse effects were analyzed by means of the isotoxicity curves for lethality, malformations, stage-dependent susceptibility, and ultrastructural features. For all experimental conditions, the CF was more toxic, up to 10 times, than the active ingredient, being the open mouth stage (S.21) the most susceptible to the herbicide. For continuous treatment conditions, the early embryonic development was the most susceptible to 2,4-D and the LC50s for 96 and 168 h were 9.06 and 7.76 mg L(-1) respectively. In addition, both the active ingredient and the CF were highly teratogenic, resulting in reduced body size, delayed development, microcephaly, agenesis of gills, and abnormal cellular proliferation processes as the main adverse effects. According to US EPA, 2,4-D in agricultural scenarios may be up to three times higher than the NOEC values for teratogenic effects reported in this study. Therefore, they might represent a risk for amphibians. This study also points out the relevance of reporting the susceptibility of embryos at different developmental stages to both the active ingredient and the CF of agrochemicals in order to protect nontarget organisms.
我们评估了 2,4-二氯苯氧乙酸丁酯(2,4-D)除草剂及其商业制剂(CF)对不同发育阶段 Rhinella(= Bufo)arenarum 胚胎的急性和短期慢性毒性。通过致死率、畸形、阶段依赖性敏感性和超微结构特征的等毒性曲线来分析不良反应。对于所有实验条件,CF 比活性成分更具毒性,高达 10 倍,开口期(S.21)对除草剂最敏感。对于连续处理条件,早期胚胎发育对 2,4-D 最敏感,96 和 168 h 的 LC50 值分别为 9.06 和 7.76 mg/L。此外,活性成分和 CF 都具有高度致畸性,导致身体大小减小、发育延迟、小头畸形、鳃缺失和异常细胞增殖过程等主要不良反应。根据美国环保署的说法,农业场景中的 2,4-D 可能比本研究报告的致畸作用的 NOEC 值高 3 倍。因此,它们可能对两栖动物构成威胁。本研究还指出,为了保护非目标生物,报告活性成分和农用化学品 CF 对不同发育阶段胚胎的敏感性具有重要意义。