Biomonitoring of glyphosate and aminomethylphosphonic acid: Current insights and future perspectives.

Glyphosate is one of the most widely used herbicides globally, raising concerns about its potential impact on human health. Biomonitoring studies play a crucial role in assessing human exposure to glyphosate and providing valuable insights into its distribution and metabolism in the body. This review aims to summarize the current trends and future perspectives in biomonitoring of glyphosate and its major degradation product of aminomethylphosphonic acid (AMPA). A comprehensive literature search was conducted, focusing on studies published between January 2000 and December 2022. The findings demonstrated that glyphosate and AMPA have been reported in different human specimens with urine as the dominance. Sample pretreatment techniques of solid-phase and liquid-liquid extractions coupled with liquid/gas chromatography-tandem mass spectrometry have achieved matrix elimination and accurate analysis. We also examined and compared the exposure characteristics of these compounds among different regions and various populations, with significantly higher levels of glyphosate and AMPA observed in Asian populations and among occupational groups. The median urinary concentration of glyphosate in children was 0.54 ng/mL, which was relatively higher than those in women (0.28 ng/mL) and adults (0.12 ng/mL). It is worth noting that children may exhibit increased susceptibility to glyphosate exposure or have different exposure patterns compared to women and adults. A number of important perspectives were proposed in order to further facilitate the understanding of health effects of glyphosate and AMPA, which include, but are not limited to, method standardization, combined exposure assessment, attention for vulnerable populations, long-term exposure effects and risk communication and public awareness.

Field evidence supports former experimental claims on the stimulatory effect of glyphosate on picocyanobacteria communities.

Glyphosate-based herbicides are the most commonly used herbicide worldwide. Although glyphosate is known to be toxic to aquatic organisms, it can also have stimulatory effects on small-size (ø <2 µm) cyanobacteria (Pcy) able to metabolize and degrade glyphosate and AMPA. Several previous experimental studies in micro- and mesocosms reported increases of Pcy abundance in response to glyphosate additions, but comparable field evidence is presently unavailable. We surveyed a large geographical area in order to collect information on Pcy abundance from lakes within the Pampa region (with over three decades of glyphosate usage) and lakes from Patagonia (with virtually no history of glyphosate usage). Fifty-two Pampean lakes and 24 Patagonian lakes were surveyed. We used three indicators of glyphosate impact: herbicide concentration, the presence of phosphonate metabolism genes (responsible for glyphosate and AMPA degradation) in environmental DNA samples, and descriptors of land use in the surrounding area of each lake. We addressed three questions: (1) is there field evidence of stimulatory effects of glyphosate on picocyanobacteria abundance? (2) is the magnitude of the effects of glyphosate in natural systems comparable to that reported under controlled experimental conditions? and (3), how do the effects of glyphosate compare to the effects of other potential environmental drivers of Pcy biomass? The collected evidence is consistent with the hypothesis that long-term agricultural practices relying on glyphosate-based technologies had important effects on freshwater microbial communities, particularly by promoting increases in picocyanobacteria abundance.

Hydrogeological features affecting spatial distribution of glyphosate and AMPA in groundwater and surface water in an agroecosystem. Córdoba, Argentina.

The study area is located in the eastern slope of Las Peñas Mountain and its adjacent oriental fluvio-aeolian-plain. Agriculture is the main activity (soybean, maize, wheat, peanuts and alfalfa) with no-tillage farming and intensive use of agrochemicals (pesticides-fertilizers). Glyphosate (N-phosphono-methylglycine) is the most common used herbicide which suffers microbial biodegradation giving aminomethylphosphonic acid (AMPA), its main metabolite. The objective of this work is to evaluate hydrogeological features which influence the presence of glyphosate and AMPA in waters. In the study area, the main flow direction of surface and groundwater is NW-SE. The unsaturated zone thickness decreases in the same direction from 60 to 0 m, so groundwater surges in low areas in the eastern sector. From the total water samples collected, glyphosate was detected in 66% of surface water samples (0.2 to 167.4 µg/L), in 15.8% of the groundwater samples (1.3 to 2 µg/L) and in the harvested precipitation sample (0.2 µg/L). AMPA was found in 33% of surface water and 15.8% of groundwater. The herbicide detection was related to areas with the shallowest water table (< 4 m), low hydraulic conductivity in the aquifer (K = 1.5 m/d), low hydraulic gradient (i = 0.16%) and very low flow velocity (0.02 m/d). The most outstanding result is that the groundwater presents higher values in comparison with the surface water samples, which can be explained by the greater dilution capacity of streams. The detection of glyphosate and AMPA in the unconfined aquifer shows that the application for decades under the prevailing agricultural model exceeds the degradation potential of the soil and the unsaturated zone, causing groundwater contamination.