Glyphosate, a chelating agent—relevant for ecological risk assessment?

Abstract

Glyphosate-based herbicides (GBHs), consisting of glyphosate and formulants, are the most frequently applied herbicides worldwide. The declared active ingredient glyphosate does not only inhibit the EPSPS but is also a chelating agent that binds macro- and micronutrients, essential for many plant processes and pathogen resistance. GBH treatment may thus impede uptake and availability of macro- and micronutrients in plants. The present study investigated whether this characteristic of glyphosate could contribute to adverse effects of GBH application in the environment and to human health. According to the results, it has not been fully elucidated whether the chelating activity of glyphosate contributes to the toxic effects on plants and potentially on plant–microorganism interactions, e.g., nitrogen fixation of leguminous plants. It is also still open whether the chelating property of glyphosate is involved in the toxic effects on organisms other than plants, described in many papers. By changing the availability of essential as well as toxic metals that are bound to soil particles, the herbicide might also impact soil life, although the occurrence of natural chelators with considerably higher chelating potentials makes an additional impact of glyphosate for most metals less likely. Further research should elucidate the role of glyphosate (and GBH) as a chelator, in particular, as this is a non-specific property potentially affecting many organisms and processes. In the process of reevaluation of glyphosate its chelating activity has hardly been discussed.

Glyphosate and glyphosate‐based herbicide exposure during the peripartum period affects maternal brain plasticity, maternal behaviour and microbiome

“…A third hypothesis for molecular target is the chelating role of Glyphosate, particularly with divalent cations. The presence of divalent cations, including Ca 2+ , Fe 2+ or Mg 2+ , is of fundamental importance for the organisms because they participate in various physiological functions, including bone formation and cellular communication (Ca 2+ ), oxygen transport (Fe 2+ ) and enzyme cofactors (Ca 2+ , Mg 2+ ), to name just a few.…”

“…Mg 2+ , Ca 2+ , Fe 2+ , Mn 2+ , Cu 2+ , Zn 2+ ). This chelating effect in vivo is unclear and the outcome poorly investigated . A reduction of these elements could lead to a significant alteration of most enzymatic cascades that usually not only require metallic cofactors but also could indirectly alter the microbiota.…”

“…This chelating effect in vivo is unclear and the outcome poorly investigated. 50,51 A reduction of these elements could lead to a significant alteration of most enzymatic cascades that usually not only require metallic cofactors but also could indirectly alter the microbiota. Therefore, the present study aimed to compare the potential effects of relatively low dose (5 mg kg -1 d -1 , one-tenth of the NOAEL, and pre-and post-synaptic protein densities (synaptophysin-IR and PSD95-IR) in the hippocampus.…”

“…It should be noted that oxidative stress, independent of NMDA receptor activation, was also observed in other tissues, such as the liver and the kidney, following exposure to Glyphosate or various Glyphosatebased herbicides [140][141][142][143]. A third hypothesis for molecular target is the chelating role of Glyphosate,50,[144][145][146] particularly with divalent cations. The presence of divalent cations, including Ca 2+ , Fe 2+ or Mg 2+ , is of fundamental importance for the organisms because they participate in various physiological functions, including bone formation and cellular communication (Ca 2+ ), oxygen transport (Fe 2+ ) and enzyme cofactors (Ca 2+ , Mg 2+ ), to name just a few.…”

Re-registration Challenges of Glyphosate in the European Union

“…A wide range of ecotoxicological and human health problems related to glyphosate and its formulated PPPs have been indicated (Székács and Darvas, 2012;Mensah et al, 2015;Kurenbach et al, 2017), partially related to the chelating properties of glyphosate (Mertens et al, 2018). Moreover, ecotoxicological and resistance-related consequences of the extended use of glyphosate (Schütte et al, 2017) or of the use of GT GM crops (Pandolfo et al, 2018) have been emphasized, along with effects non-target terrestrial plants as well (Cederlund, 2017).…”