Mortality, teratogenicity and growth inhibition of three glyphosate formulations using Frog Embryo Teratogenesis Assay‐Xenopus

Ample evidence around the world exists suggesting a link between exposure to glyphosate, toxicity and perturbed physiological functions in non‐target organisms. Although glyphosate formulations are widely used for weed and alien plant management, their ecotoxicological information remain scanty. Using the 96‐hour Frog Embryo Teratogenesis Assay‐Xenopus protocol, embryotoxicity and teratogenicity of three glyphosate‐based formulations were assessed. Embryos of Xenopus laevis were exposed to Roundup, Kilo Max and Enviro Glyphosate at concentration of 0.3‐1.3, 130‐280 and 320‐560 mg acid equivalent (a.e.)/L respectively. The results showed Roundup to be more toxic than the other formulations with a 96‐hour LC50 of 1.05 mg a.e/L. compared with 207 mg a.e./L, and 466 mg a.e./L for Kilo Max and Enviro Glyphosate respectively. Although, both Roundup and Kilo Max formulations show inhibition on growth of the embryo‐larva (P ˂ .05), the minimum concentration inhibiting growth ratios of the three formulations was >0.30 baseline, indicating no significant growth inhibiting effect in the formulations. For teratogenicity, Roundup and Enviro Glyphosate formulations exhibited increasing teratogenic traces, with the teratogenic index at 1.7 and 1.6 respectively. Kilo Max formulation shows low teratogenicity with the teratogenic index at 1.4. Characteristic malformation induced by these formulations included generalized edema, cardiac and abdominal edema, improper gut formation and axial malformations. This study confirms that these formulations could be a potential physiological and ecological health disruptor, particularly concerning teratogenicity and growth disruption. Further studies to characterize the contributions of their surfactants will be invaluable. The use of glyphosate globally and particularly in South Africa for weed control is increasing, yet their ecotoxicology information, particularly concerning amphibians remains limited. Using the Frog Embryo Teratogenesis Assay‐Xenopus protocol, the Roundup formulation was shown to exhibit embryotoxicity and increasing teratogenicity potential with a teratogenic index of 1.7. Although Enviro Glyphosate had low toxicity but increasing teratogenicity was observed with the teratogenic index at 1.6, Kilo Max showed low toxicity and teratogenicity. This study confirms that Roundup and Environ Glyphosate could have potential negative ecological impacts, and further studies on the impacts of their surfactants are required.