Differential genotoxicity of Roundup® formulation and its constituents in blood cells of fish (Anguilla anguilla): considerations on chemical interactions and DNA damaging mechanisms

Abstract

It has been widely recognized that pesticides represent a potential threat in aquatic ecosystems. However, the knowledge on the genotoxicity of pesticides to fish is still limited. Moreover, genotoxic studies have been almost exclusively focused on the active ingredients, whereas the effect of adjuvants is frequently ignored. Hence, the present study addressed the herbicide Roundup®, evaluating the relative contribution of the active ingredient (glyphosate) and the surfactant (polyethoxylated amine; POEA) to the genotoxicity of the commercial formulation on Anguilla anguilla. Fish were exposed to equivalent concentrations of Roundup® (58, 116 μg L⁻¹), glyphosate (17.9, 35.7 μg L⁻¹) and POEA (9.3, 18.6 μg L⁻¹), during 1 and 3 days. The comet assay was applied to blood cells, either as the standard procedure, or with an extra step involving DNA lesion-specific repair enzymes in an attempt to clarify DNA damaging mechanisms. The results confirmed the genotoxicity of Roundup®, also demonstrating the genotoxic potential of glyphosate and POEA individually. Though both components contributed to the overall genotoxicity of the pesticide formulation, the sum of their individual effects was never observed, pointing out an antagonistic interaction. Although POEA is far from being considered biologically inert, it did not increase the risk associated to glyphosate when the two were combined. The analysis of oxidatively induced breaks suggested that oxidation of DNA bases was not a dominant mechanism of damage. The present findings highlighted the risk posed to fish populations by the assessed chemicals, jointly or individually, emphasizing the need to define regulatory thresholds for all the formulation components and recommending, in particular, the revision of the hazard classification of POEA.

Evaluation of genotoxicity by comet assay (single-cell gel electrophoresis) in tissues of the fish Cyprinus carpio during sub-lethal exposure to Karanjin

“…Another important reason for DNA damage may be the inhibition of enzymes that replicate or repair DNA ( Singh et al, 1988;Aruoma, Halliwell, Gajewski, & Dizdaroglu, 1991;Guilherme, Santos, Barroso, Gaivao, & Pacheo, 2012). The intactness of the DNA is the important part of the normal cellular process.…”

Time-Effect Relationship of Toxicity Induced by Roundup® and Its Main Constituents in Liver of Carassius Auratus

“…The original formulation of Roundup® contains isopropylamine salt of glyphosate (G.I.S) as the active ingredient and polyoxyethylene amine (POEA) as the surfactant agent [2]. Since Roundup® can easily reach the aquatic systems by runoff, drainage, leaching or inadvertent aerial overspray, the herbicide represents a dangerous and widely spread group of environmental contaminants [3]. However, the knowledge on the timeeffect of toxicity induced by environmental concentration of Roundup® and its main constituents to fish is still limited.…”

Glyphosate, pathways to modern diseases IV: cancer and related pathologies

“…They found a sixfold increase in a genetic damage indicator (GDI) in erythrocytes, using the "comet" assay method. Similarly, the comet assay applied to goldfish erythrocytes revealed DNA damage following exposure to glyphosate [42], and studies on exposure of eels to realistic concentrations of Roundup and the principal individual components, glyphosate and the surfactant polyethoxylated amine (POEA) in isolation, confirmed DNA damage in erythrocytes [43,44].…”