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Thyroid hormones play critical roles in body growth and development as well as reproduction. They also influence the activities of a wider variety of tissues and biological functions, such as osmoregulation, metabolism, and especially metamorphosis in organisms, such as frogs. These complex activities of thyroid hormones are prone to disruption by agricultural pesticides, often leading to modulation of growth and the reproductive system in particular. These substances include Glufosinate ammonium, Glyphosates, Imazapyr, Penoxsulam, and Diquat dibromide among other herbicides. In this study, the standardized Xenopus Metamorphosis Assay protocol was used to assess the potential thyroid-modulatory properties of the Glufosinate ammonium Basta formulation, at relevant environmental concentrations (0.05 mg/L, 0.15 mg/L, and 0.25 mg/L) for 21 days. The results showed that this formulation only reduced the hind-limb length among the morphological endpoints. Histological evaluation showed that the mean thyroid gland area and the mean thyroidal follicle epithelium height were significantly increased following 0.15 and 0.25 mg/L exposures. The present study confirmed that this Basta formulation interacts with the thyroid axis and therefore potentially pose health hazard to amphibian in particular and potentially metamorphic aquatic vertebrates. Furthermore, the result is a signal of inherent potential thyroid disrupting activities that must be further investigated and characterised in some of the aquatic herbicide formulations to safeguard the aquatic biodiversity.

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 LC50 estimates were 0.83 mg/L acid equivalent (a.e.), 36 mg/L a.e., and 2.2 mg/L a.e., whereas the EC50 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.

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

Thyroid hormones play critical roles in body growth and development as well as reproduction. They also influence the activities of a wider variety of tissues and biological functions, such as osmoregulation, metabolism, and especially metamorphosis in organisms, such as frogs. These complex activities of thyroid hormones are prone to disruption by agricultural pesticides, often leading to modulation of growth and the reproductive system in particular. These substances include Glufosinate ammonium, Glyphosates, Imazapyr, Penoxsulam, and Diquat dibromide among other herbicides. In this study, the standardized Xenopus Metamorphosis Assay protocol was used to assess the potential thyroid-modulatory properties of the Glufosinate ammonium Basta formulation, at relevant environmental concentrations (0.05 mg/L, 0.15 mg/L, and 0.25 mg/L) for 21 days. The results showed that this formulation only reduced the hind-limb length among the morphological endpoints. Histological evaluation showed that the mean thyroid gland area and the mean thyroidal follicle epithelium height were significantly increased following 0.15 and 0.25 mg/L exposures. The present study confirmed that this Basta formulation interacts with the thyroid axis and therefore potentially pose health hazard to amphibian in particular and potentially metamorphic aquatic vertebrates. Furthermore, the result is a signal of inherent potential thyroid disrupting activities that must be further investigated and characterised in some of the aquatic herbicide formulations to safeguard the aquatic biodiversity.