Aquatic ecotoxicity of glyphosate, its formulations, and co-formulants: evidence from 2010 to 2023

Abstract Glyphosate (GLY), the most widely used herbicide active ingredient (AI) in the world, is frequently detected in aquatic environments where it can affect non-target organisms. Globally, more than 2000 commercial GLY-based herbicides (GBHs) are used to control weeds. Non-target organisms are exposed to complex pesticide formulations under real environmental conditions, but the co-formulants contained in GBHs are classified as so-called inert and inactive ingredients in terms of their biological effects. The main objective of this comprehensive review is to compile the results of aquatic ecotoxicological studies on the side-effects of GLY, GBHs, and their formulating agents. Based on the results demonstrated for a variety of plant and animal aquatic organisms, oxidative stress appears to be a major trigger for these adverse effects, affecting the integrity of DNA and other biochemical functions. Furthermore, there is evidence of impairment of various physiological and behavioral functions. Adverse effects of GLY and GBHs have been observed even at very low concentrations. There are also differences in the sensitivity of the aquatic organisms tested, even with similar lifestyles, habitats or identical taxa. The studies typically investigate the short-term effects of a single exposure to GLY/GBH on a single species, whilst in reality multiple applications of GBHs together with other pesticides are common during a cropping cycle. Moreover, the interactions between GLY/GBHs and other aquatic contaminants are rarely studied. Higher toxicity of GBHs compared to GLY alone has often been observed, demonstrating that co-formulants can be highly toxic on their own and markedly increase the toxicity of the GBH formulation. The possible impurities in GBHs, such as heavy metals, can cause additional problems for the environment and food safety. The widespread and massive use of GBHs leads to increased exposure and environmental hazards. In addition, the need for a revision of the risk assessment system is emphasized. According to the results of aquatic ecotoxicological studies, the current use and pollution of the aquatic environment by GLY/GBHs is highly problematic and cannot be considered environmentally sustainable. It is, therefore, necessary to at least tighten the permitted forms of use.