Effects of glyphosate and its commercial formulation, Roundup® Ultramax, on liver histology of tadpoles of the neotropical frog, Leptodactylus latrans (amphibia: Anura)

Abstract

In the last years, the agricultural expansion has led to an increased use of pesticides, with glyphosate as the most widely used worldwide. This is also the situation in Argentina, where glyphosate formulations are the most commercialized herbicides. It is known that glyphosate formulations are much more toxic than the active ingredient, and this difference in toxicity can be attributed to the adjuvants present in the formula. In this context, the aim of the present study was to evaluate and compare sub-lethal histological effects of the glyphosate formulation Roundup Ultramax and glyphosate active ingredient on Leptodactylus latrans tadpoles at Gosner-stage 36. Semi-static bioassays were performed using 96 h of exposure with Roundup Ultramax formulation (RU; 0.37-5.25 mg a.e./L), glyphosate (GLY; 3-300 mg/L), and a control group. RU exposure showed an increment in the melanomacrophagic cells (MMc) and melanomacrophagic centers (MMCs) from 0.37 mg a.e./L. GLY exposure showed a significant increment in the number of MMc from 15 mg/L, and of MMCs from 3 mg/L. Also, histopathological lesions were observed in the liver of tadpoles exposed to both, GLY and RU. These lesions included: lipidosis and hepatic congestion, but only RU showed significant differences respect to control, with a LOEC value of 2.22 mg a.e./L for both effects. In sum, this study represents the first evidence of adverse effects of glyphosate and RU formulation on the liver of anuran larvae at concentrations frequently found in the environment.

Idiosyncratic liver pigment alterations of five frog species in response to contrasting land use patterns in the Brazilian Cerrado

“…Changes in the amount of melanin was found in frogs experimentally exposed to several xenobiotics. In these experiments, the variation in melanin was due to several compounds (reviewed in De Oliveira et al (2017)), such as polycyclic aromatic hydrocarbons (PAHs;Fanali et al, 2018), herbicides (e.g., atrazine and glyphosate; Pérez-Iglesias et al, 2019;Bach et al, 2018), drugs, and endocrine disrupters (Gregorio et al, 2016). Here, we found large amounts of atrazine in the area under agriculture influence (more than 5,000 times the limit accepted by Brazilian legislation, i.e., 5,349.940 µg/L).…”

Re-registration Challenges of Glyphosate in the European Union

“…Teratogenic effects were reported in a treefrog (Scinax nasicus) (Lajmanovich et al, 2003) and in the embryo of the African clawed frog (Xenopus laevis) (Paganelli et al, 2010) in response to exposure to Glyfos R or Roundup Classic R at levels corresponding to 3-7.5 and 96-160 mg/l glyphosate concentrations, respectively. Hepatotoxicity of glyphosate and Roundup Ultramax R was observed in tadpoles of the neotropical frog Leptodactylus latrans (Bach et al, 2018), but the formulated herbicide product was found 10-fold more toxic than glyphosate, leading to histopathologic lesions at a level corresponding to a glyphosate concentration of 0.37 mg/l. Teratogenicity is not exclusively related to POEA, as a POEAfree micro-emulsion formulation containing polyethoxylated isotridecyletherpropylamine as a surfactant, Roundup R Power 2.0 has been found to exert embryotoxicty on X. laevis in the frog embryo teratogenesis assay-Xenopus (FETAX) with a 96-h EC 50 value of 7.8 mg/l, while glyphosate was not found to be embryolethal, only causing edemas at the highest concentration tested, 50 mg/l (Bonfanti et al, 2018).…”

Peer Review #1 of "Idiosyncratic liver pigment alterations of five frog species in response to contrasting land use patterns in the Brazilian Cerrado (v0.1)"

“…Changes in the amount of melanin was found in frogs experimentally exposed to several xenobiotics. In these experiments, the variation in melanin was due to several compounds (reviewed in De Oliveira et al 2017), such as polycyclic aromatic hydrocarbons (PAHs; Fanali et al 2018), herbicides (e.g., atrazine and glyphosate; Pérez-Iglesias et al 2019;Bach et al 2018), drugs, and endocrine disrupters (Gregorio et al 2016). Here, we found large amounts of atrazine in the area under agriculture influence (more than 5,000 time the limit accepted by Brazilian legislation, i.e.…”