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.

Hormesis, the Individual and Combined Phytotoxicity of the Components of Glyphosate-Based Formulations on Algal Growth and Photosynthetic Activity

“…Based on the scientific literature and our results, significant differences can be observed in the sensitivity of different algal and cyanobacterial species to the effects of glyphosate and its formulated herbicides, even within the same taxa [ 20 , 70 , 71 , 72 , 113 ]. Therefore, the significant differences that can be observed in the available toxicity data are not surprising.…”

“…As a result of excessive global use, glyphosate has become a ubiquitous contaminant in aquatic ecosystems [ 19 , 20 ]. The appearance and concentration of glyphosate in the different environmental elements (e.g., soil, ground and surface waters) are highly influenced by several abiotic (e.g., hydrological conditions, pH, suspended materials), biotic (e.g., activity and composition of the microbial community), and climatic factors (e.g., rainfall frequency and intensity) [ 21 , 22 , 23 ], in addition to the condition of pesticide treatments (e.g., frequency and timing of the treatment) [ 22 , 24 ].…”

“…However, the presence of the GBH co-formulant POEA has been observed extensively in soils collected from agricultural fields of the mid-western states in the USA, where the cultivation of genetically modified glyphosate-tolerant crops is concentrated [ 44 ]. Additionally, studies have demonstrated the persistence of POEA in soil along with glyphosate and AMPA [ 44 , 45 , 46 ] and possible access to natural waterways [ 20 , 43 , 45 ]. Due to their low environmental impacts and biodegradability [ 47 ], APGs are commonly used as additives in pesticide formulations, personal skin products, and drugs [ 48 , 49 ].…”

“…The toxic effects of glyphosate and its formulations have been studied in numerous aquatic organisms, such as various algae species [ 51 , 52 ], crustaceans (e.g., Daphnia magna ) [ 53 ], mollusks [ 54 ], fish [ 55 ], and amphibians [ 56 ]. Based on the results of ecotoxicological testing performed on a wide range of aquatic plant and animal organisms, the damage to different physiological and behavioral functions was demonstrated [ 20 ]. In aquatic ecosystems, algal communities constitute the primary producer level and the majority of biomass, playing a key role in the oxygen cycle of water and the atmosphere.…”

“…Various algal species are widely used for environmental biological monitoring [ 62 ] and bioremediation activities [ 63 ]. The different effects of glyphosate, its metabolite, co-formulants, and/or commercial herbicide formulations on green algae and cyanobacterial species are summarized in Table 1 partially based on our previous review about aquatic ecotoxicity of glyphosate, its formulations, and co-formulants [ 20 ].…”