Mansano Adrislaine S, Moreira Raquel A, Dornfeld Hugo C, Freitas Emanuela C, Vieira Eny M, Sarmento Hugo, Rocha Odete, Seleghim Mirna H R
Department of Ecology and Evolutionary Biology, Federal University of São Carlos, Rodovia Washington Luis, km 235, 13565-905 São Carlos, SP, Brazil.
Department of Ecology and Evolutionary Biology, Federal University of São Carlos, Rodovia Washington Luis, km 235, 13565-905 São Carlos, SP, Brazil.
Ecotoxicol Environ Saf. 2017 Aug;142:312-321. doi: 10.1016/j.ecoenv.2017.04.024. Epub 2017 Apr 28.
In aquatic environments, organisms are often exposed to mixtures of several pesticides. In this study, the effects of carbofuran and diuron and their mixtures on the microalgae Raphidocelis subcapitata were investigated. For this purpose, toxicity tests were performed with the single compounds (active ingredients and commercial formulations) and their combinations (only active ingredients). According to the results, the toxicity of active ingredients and their commercial formulations to R. subcapitata was similar. In the single exposures, both carbofuran and diuron inhibited significantly the R. subcapitata growth and caused physiological (chlorophyll a content) and morphological (complexity and cell size) changes in cells, as captured by flow cytometry single-cell properties. Regarding the mixture toxicity tests, data fitted to both reference models, concentration addition (CA) and independent action (IA), and evidenced significant deviations. After the CA fitting, dose-ratio dependent deviation had the best fit to the data, demonstrating synergism caused mainly by diuron and antagonism caused mainly by carbofuran. After fitting the IA model, a synergistic deviation represented the best fit for the diuron and carbofuran mixtures. In general, the two reference models indicated the occurrence of synergism in the mixtures of these compounds, especially when diuron was the dominant chemical in the combinations. The increased toxicity caused by the mixture of these pesticides could pose a greater environmental risk for phytoplankton. Thus, exposure to diuron and carbofuran mixtures must also be considered in risk assessments, since the combination of these compounds may result in more severe effects on algae population growth than single exposures.
在水生环境中，生物常常会接触到几种农药的混合物。在本研究中，调查了克百威和敌草隆及其混合物对微藻小形色球藻的影响。为此，使用单一化合物（活性成分和商业制剂）及其组合（仅活性成分）进行了毒性试验。结果表明，活性成分及其商业制剂对小形色球藻的毒性相似。在单一暴露试验中，克百威和敌草隆均显著抑制了小形色球藻的生长，并导致细胞发生生理（叶绿素a含量）和形态（复杂性和细胞大小）变化，这些变化通过流式细胞仪单细胞特性得以捕捉。关于混合物毒性试验，数据符合两种参考模型，即浓度相加（CA）和独立作用（IA），并显示出显著偏差。在进行CA拟合后，剂量比依赖性偏差与数据拟合效果最佳，表明主要由敌草隆引起协同作用，主要由克百威引起拮抗作用。在拟合IA模型后，协同偏差对敌草隆和克百威混合物的拟合效果最佳。总体而言，这两种参考模型表明这些化合物的混合物中存在协同作用，尤其是当敌草隆在组合中占主导地位时。这些农药混合物导致的毒性增加可能对浮游植物构成更大的环境风险。因此，在风险评估中也必须考虑接触敌草隆和克百威混合物的情况，因为这些化合物的组合可能对藻类种群生长产生比单一暴露更严重的影响。
