Negligible Toxicokinetic Differences of Glyphosate by Different Vehicles in Rats

Glyphosate is a non-selective herbicide. Although glyphosate is not acutely toxic, the intake of glyphosate-based herbicides has caused many accidents. Some studies have suggested that surfactants might be the cause. The purpose of this study was to compare the toxicokinetic (TK) properties of glyphosate according to different vehicles in rats. Glyphosate (1%) was dissolved in distilled water (DW), polyoxyethylene tallow amine (POEA), and Tween 20. After a single oral treatment of glyphosate (50 mg/kg), blood was collected at time intervals, and glyphosate concentrations in the target organ (liver and kidney) were determined 24 h after final blood collection. All samples were analyzed using LC-MS/MS. The TK parameters of glyphosate were similar in the DW and Tween 20 groups. However, there were significant differences in T(max) and volume of distribution (V(d)) between the DW and POEA group (p < 0.05). Glyphosate was absorbed about 10 times faster in POEA group rather than DW, and exhibited a higher distribution. However, other important TK parameters of T(1/2), AUC, and C(max) were not statistically different among the different vehicle groups. Although glyphosate concentration in the liver was significantly higher in the POEA group than in the DW group, there was no significant difference in the kidney. These results indicate that the toxicokinetics of glyphosate are not significantly affected by POEA. It can be concluded that POEA toxicity itself can be attributed to the acute toxicity of glyphosate-containing products.