An Examination of Potential Renal Toxicity from Low Dose Glyphosate Exposure in Human Subjects

Background Widespread usage of glyphosate has resulted in contamination of water, air, and food products. The objective of this study was to examine the prevalence and magnitude of environmental exposure to glyphosate among subjects from the general population, as well as assess the potential risk of renal toxicity associated with these exposures. Methods Concentrations of glyphosate and its environmental breakdown product aminomethylphosphonic acid (AMPA) were measured in the urine of 168 random, de-identified subjects using liquid chromatograph-tandem mass spectrometry (LC-MS/MS) to determine the frequency of detection. Glyphosate doses producing the observed glyphosate in urine were estimated for comparison with regulatory safe exposure limits. Forty-eight of these samples were further screened for biomarkers of renal injury, with urinary extracellular vesicles prepared from a subset of 12 of these samples for miRNA analysis. Results Glyphosate was detected in the urine of 40% of all subjects with a maximum concentration of 25.3 µg/L, and AMPA was detected in 6.5% of all subjects with a maximum concentration of 0.86 µg/L. Estimated glyphosate doses corresponding to urinary levels were 1–2 orders of magnitude below U.S. and European exposure limits. There was no relationship between glyphosate or glyphosate plus AMPA concentrations in urine and any of 21 urinary biomarkers of renal injury, and no concentration related increase in urinary extracellular vesicular miRNAs previously associated with a high acute glyphosate exposure in humans. Conclusions Exposure to glyphosate, as reflected in urinary glyphosate levels, is common among members of the general public in the United States. Observed levels were below established exposure limits, and our data did not document adverse effects of glyphosate on the kidneys at doses at which the general population is exposed. However, more work is needed in subjects with known chronic glyphosate exposure before potential effects from prevalent low doses can be ruled out.