First evaluation of novel potential synergistic effects of glyphosate and arsenic mixture on Rhinella arenarum (Anura: Bufonidae) tadpoles

Abstract

The toxicity of glyphosate-based herbicide (GBH) and arsenite (As(III)) as individual toxicants and in mixture (50:50 v/v, GBH-As(III)) was determined in Rhinella arenarum tadpoles during acute (48 h) and chronic assays (22 days). In both types of assays, the levels of enzymatic activity [Acetylcholinesterase (AChE), Carboxylesterase (CbE), and Glutathione S-transferase (GST)] and the levels of thyroid hormones (triiodothyronine; T3 and thyroxine; T4) were examined. Additionally, the mitotic index (MI) of red blood cells (RBCs) and DNA damage index were calculated for the chronic assay. The results showed that the LC50 values at 48 h were 45.95 mg/L for GBH, 37.32 mg/L for As(III), and 30.31 mg/L for GBH-As(III) (with similar NOEC = 10 mg/L and LOEC = 20 mg/L between the three treatments). In the acute assay, Marking's additive index (S = 2.72) indicated synergistic toxicity for GBH-As(III). In larvae treated with GBH and As(III) at the NOEC-48h (10 mg/L), AChE activity increased by 36.25% and 33.05% respectively, CbE activity increased by 22.25% and 39.05 % respectively, and GST activity increased by 46.75% with the individual treatment with GBH and by 131.65 % with the GBH-As(III) mixture. Larvae exposed to the GBH-As(III) mixture also showed increased levels of T4 (25.67 %). In the chronic assay at NOEC-48h/8 (1.25 mg/L), As(III) and GBH-As(III) inhibited AChE activity (by 39.46 % and 35.65%, respectively), but did not alter CbE activity. In addition, As(III) highly increased (93.7 %) GST activity. GBH-As(III) increased T3 (97.34%) and T4 (540.93%) levels. Finally, GBH-As(III) increased the MI of RBCs and DNA damage. This study demonstrated strong synergistic toxicity of the GBH-As(III) mixture, negatively altering antioxidant systems and thyroid hormone levels, with consequences on RBC proliferation and DNA damage in treated R. arenarum tadpoles.

Evaluation of the Acute Effects of Arsenic on Adults of the Neotropical Native Fish Cnesterodon decemmaculatus Using a Set of Biomarkers

“…The damaged nucleoids (II + III + IV) increased 33% at 0.5 mg As/L and showed a significant increase at 1.0 (39%) and 5.0 mg As/L (55%). It is worthwhile to mention the study of Lajmanovich et al (2019), who evaluated the combined effect of arsenite and glyphosate on Rhinella arenarum tadpoles. They found a synergistic effect evidenced by an increase in the GDI of larvae exposed for 22 days to the mixture, and highlighted the potential risk for aquatic wildlife organisms inhabiting freshwater bodies with mixtures of glyphosate‐based herbicides and common forms of inorganic As species.…”

Conflictos por el agua y el uso de agroquímicos en Salta y Santiago del Estero, Argentina: un análisis desde la ecología política

“…16 Contaminante inorgánico de alta toxicidad presente en el agua, cuya exposición crónica ha sido asociada a múltiples patologías (conocidos como HACRE: hidroarsenicismo crónico regional endémico). 17 Lajmanovich et al, 2019. Revelli, Sbodio y Costa, 2016 La caracterización provincial y departamental se sustenta en los datos del Censo Nacional de Población, Hogares y Viviendas (CNPHyV) elaborado por el Instituto Nacional de Estadísticas y Censos (2010).…”

The Effect of Glyphosate And Ciprofloxacin Eexposure On The Gut Bacterial Microbiota Diversity of Rhinella Arenarum (Anura: Bufonidae) Tadpoles

“…Bioassays solutions were prepared using a commercial formulation of a GBH (74.7 % active ingredient, Nphosphonomethyl glycine and inert adjuvant quantum satis; Roundup Ultra-Max®, Monsanto© Argentina;), and CIP (Sigma-Aldrich, Germany). Ultra-Max® GBH formulation and Sigma-Aldrich CIP were analytically evaluated in previous works, and for both cases, the error did not exceed 5% of the nominal concentrations (Lajmanovich et al 2019;Peltzer et al 2017). The chemicals were tested individually in nominal concentrations considered as relevant in worst-case scenarios for natural lentic aquatic systems (Cuzziol Boccioni et al 2020): GBH = 2,5 mg L ¹ and CIP = 100 µg.…”