Instituto de Investigación e Ingeniería Ambiental, IIIA, UNSAM, CONICET, 3iA, Campus Miguelete, 25 de mayo y Francia, 1650, San Martín, Provincia de Buenos Aires, Argentina.
Environ Sci Pollut Res Int. 2021 Aug;28(31):41772-41779. doi: 10.1007/s11356-021-13691-2. Epub 2021 Mar 31.
There is a great concern worldwide about the global decline of amphibians, particularly by agrochemical pollution. The aim of this study was to assess oxidative stress and genotoxicity of a commercial formulation of the insecticide dimethoate in Rhinella arenarum larvae, using sublethal biomarkers. The 24- and 96-h LC50 values of dimethoate to R. arenarum were 48.81 and 38.86 mg L, while the 96-h no observed effect concentration (NOEC) value was 20 mg L. For sublethal biomarker assays, R. arenarum larvae were exposed to 1.25, 2.5, and 5% of the 96-h NOEC (0.25, 0.5, and 1 mg L dimethoate, respectively). After 96 h of exposure, inhibition of catalase (CAT) and glutathione S-transferase (GST) activities were registered. Also, an increased superoxide dismutase (SOD) activity was observed in larvae exposed to the highest concentration (1 mg L). Lipid peroxidation by increased thiobarbituric acid reactive substance levels in larvae exposed to 0.5 and 1 mg L was detected. No differences in micronuclei frequency between treatments and negative control were observed. These results demonstrate the oxidative toxicity of dimethoate at sublethal concentrations in Rhinella arenarum larvae. The disruption of defense mechanisms may contribute to a deleterious impact on amphibian populations from habitats exposed to this organophosphorus insecticide.
全世界都非常关注两栖动物的全球减少，特别是由于农用化学品污染。本研究的目的是使用亚致死生物标志物评估杀虫剂乐果在 Rhinella arenarum 幼虫中的氧化应激和遗传毒性。乐果对 Rhinella arenarum 的 24 小时和 96 小时 LC50 值分别为 48.81 和 38.86mg/L，而 96 小时无观察到效应浓度（NOEC）值为 20mg/L。对于亚致死生物标志物测定，Rhinella arenarum 幼虫暴露于 96 小时 NOEC 的 1.25%、2.5%和 5%（分别为 0.25、0.5 和 1mg/L 乐果）。暴露 96 小时后，检测到过氧化氢酶（CAT）和谷胱甘肽 S-转移酶（GST）活性受到抑制。此外，在暴露于最高浓度（1mg/L）的幼虫中观察到超氧化物歧化酶（SOD）活性增加。在暴露于 0.5 和 1mg/L 的幼虫中检测到丙二醛（TBARS）水平增加导致的脂质过氧化。在处理组和阴性对照组之间未观察到微核频率的差异。这些结果表明，乐果在 Rhinella arenarum 幼虫中的亚致死浓度下具有氧化毒性。防御机制的破坏可能导致暴露于这种有机磷杀虫剂的生境中的两栖动物种群受到有害影响。
