Department of Botany and Zoology, Stellenbosch University, Stellenbosch, South Africa.
Zoology and Environmental Biology, Lagos State University, Ojo, Lagos, Nigeria.
Arch Environ Contam Toxicol. 2021 May;80(4):708-716. doi: 10.1007/s00244-020-00756-5. Epub 2020 Sep 8.
Globally, amphibians are experiencing widespread abnormalities and population declines. One potential contributor to these challenges is the use of pesticides, particularly aquatic herbicides applied to aquatic habitats inhabited by amphibians. Critical issues of concern are the potential toxicity and teratogenicity of these herbicides towards amphibians. Using the FETAX protocol, three globally used formulations, including diquat dibromide (Midstream), glufosinate ammonium (Basta), and imazapyr (Arsenal), were assessed for embryotoxicity, teratogenicity, and growth inhibition. Developing Xenopus laevis embryos were exposed for 96 h at concentrations of 0.5-3.0 mg/L, 1.6-3.0 mg/L, and 20-45 mg/L for Midstream, Basta, and Arsenal respectively. The 96-h LC estimates were 0.83 mg/L acid equivalent (a.e.), 36 mg/L a.e., and 2.2 mg/L a.e., whereas the EC estimates were 0.24 mg/L a.e., 28.13 mg/L a.e., and 2.01 mg/L a.e. for the Midstream, Arsenal, and Basta formulations, respectively. These two estimates produced Teratogenic Index of 3.5, 1.3, and 1.1 for Midstream, Arsenal, and Basta, respectively, indicating a high risk of malformation induction by Midstream and moderate risk for Arsenal. Regarding growth inhibition, lowest observable effect concentrations of 0.5 mg/L, 25 mg/L, and 2.0 mg/L were computed for Midstream, Arsenal, and Basta, respectively, producing the minimum concentration inhibiting growth (MCIG) ratios of 0.62, 0.69, and 0.89 for the three formulations. These MICG values are higher than the standard 0.30 growth inhibitors benchmark, suggesting that the formulations are not growth inhibitors at the evaluated concentrations. This study provides evidence of the embryotoxic and teratogenic status of Midstream and the embryotoxicity of Basta. There is a need to further characterise the physiological and ecological impacts of these formulations to ensure responsible use and the safety of amphibians and other wildlife.
全球范围内，两栖动物正经历着广泛的异常和数量减少。这些挑战的一个潜在原因是农药的使用，特别是应用于两栖动物栖息的水生生境的水生除草剂。令人关注的关键问题是这些除草剂对两栖动物的潜在毒性和致畸性。使用 FETAX 方案，评估了三种全球使用的制剂，包括二氯喹啉酸二溴盐（Midstream）、草甘膦铵（Basta）和咪唑吡嗪（Arsenal），以评估其胚胎毒性、致畸性和生长抑制作用。发育中的非洲爪蟾胚胎在 0.5-3.0mg/L、1.6-3.0mg/L 和 20-45mg/L 的浓度下暴露 96 小时，分别用于 Midstream、Basta 和 Arsenal。96 小时 LC 估计值分别为 0.83mg/L 酸当量（a.e.）、36mg/L a.e. 和 2.2mg/L a.e.，而 EC 估计值分别为 0.24mg/L a.e.、28.13mg/L a.e. 和 2.01mg/L a.e. 对于 Midstream、Arsenal 和 Basta 制剂。这两个估计值分别产生了 Midstream、Arsenal 和 Basta 的致畸指数 3.5、1.3 和 1.1，表明 Midstream 有很高的畸形诱导风险，而 Arsenal 有中度风险。关于生长抑制，计算出 Midstream、Arsenal 和 Basta 的最低可见效应浓度分别为 0.5mg/L、25mg/L 和 2.0mg/L，产生的三种制剂的最低抑制生长浓度（MCIG）比值分别为 0.62、0.69 和 0.89。这些 MICG 值高于标准的 0.30 生长抑制剂基准，表明这些制剂在评估浓度下不是生长抑制剂。本研究提供了 Midstream 胚胎毒性和致畸性以及 Basta 胚胎毒性的证据。需要进一步描述这些制剂的生理和生态影响，以确保负责任地使用这些制剂，并确保两栖动物和其他野生动物的安全。
