Glyphosate: environmental contamination, toxicity and potential risks to human health via food contamination

Abstract

Glyphosate has been the most widely used herbicide during the past three decades. The US Environmental Protection Agency (EPA) classifies glyphosate as 'practically non-toxic and not an irritant' under the acute toxicity classification system. This classification is based primarily on toxicity data and due to its unique mode of action via a biochemical pathway that only exists in a small number of organisms that utilise the shikimic acid pathway to produce amino acids, most of which are green plants. This classification is supported by the majority of scientific literature on the toxic effects of glyphosate. However, in 2005, the Food and Agriculture Organisation (FAO) reported that glyphosate and its major metabolite, aminomethylphosphonic acid (AMPA), are of potential toxicological concern, mainly as a result of accumulation of residues in the food chain. The FAO further states that the dietary risk of glyphosate and AMPA is unlikely if the maximum daily intake of 1 mg kg(-1) body weight (bw) is not exceeded. Research has now established that glyphosate can persist in the environment, and therefore, assessments of the health risks associated with glyphosate are more complicated than suggested by acute toxicity data that relate primarily to accidental high-rate exposure. We have used recent literature to assess the possible risks associated with the presence of glyphosate residues in food and the environment.

Oxidative stress, cholinesterase activity, and DNA damage in the liver, whole blood, and plasma of Wistar rats following a 28-day exposure to glyphosate

“…A twoyear rat study (35) demonstrated changes in urine and organ biochemical parameters as well as in proteomic and metabolomic profile (35). Although the toxicity of glyphosate can be both dose-and species-dependent (36) -aquatic organisms seem to be more sensitive -new studies shift their concern from acute to chronic, sub-chronic, and reproductive toxicity, as more relevant (37).…”

“…With knowledge this limited, we need to go further to investigate the toxicokinetic profile of glyphosate with multiple doses, ranging between low and high for mechanistic understanding and key events in the biological pathways as well as time-or dosedependencies (45). The reason for looking into low doses is the new evidence of harmful effects (2,35,46,47), which gets worse with sub-chronic and chronic exposure (35,37). Glyphosate traces found in human urine and blood of agricultural and non-agricultural workers, pregnant women and children (2,14,(48)(49)(50)(51)(52) point to a higher risk of longterm environmental exposure (53).…”

Critical Review of the Effects of Glyphosate Exposure to the Environment and Humans through the Food Supply Chain

“…Contained in plants and the soil, the herbicide has taken over the food chain of herbivores and omnivores, exposing animals and humans to contamination by glyphosate through ingestion [26].…”

Impact of field‐realistic doses of glyphosate and nutritional stress on mosquito life history traits and susceptibility to malaria parasite infection

“…It has been estimated that less than 0.1% of glyphosate‐based herbicides applied to crops reach their specific targets (Nguyen, Nguyen, Hwang, Bui, & Park, 2016). Herbicide and their degradation products are therefore found at significant levels in the environment (Bai & Ogbourne, 2016; Peruzzo, Porta, & Ronco, 2008; Struger et al, 2008) and, in particular, in aquatic systems through surface runoffs (Giesy, Dobson, & Solomon, 2000; Morrissey et al, 2015; Van Bruggen et al, 2018). Exposure to sublethal concentrations of glyphosate, pure or in formulation, induces biochemical, physiological, and behavioral alterations in many fish and amphibian species (Daam, Moutinho, Espíndola, & Schiesari, 2019; Langiano & Martinez, 2008; Mann & Bidwell, 1999; Modesto & Martinez, 2010).…”