The effect of metabolites and impurities of glyphosate on human erythrocytes (in vitro).

The toxicity of herbicides to animals and human is an issue of worldwide concern. The present study was undertaken to evaluate toxic potential of widely used pesticide - glyphosate, its metabolites: aminomethylphosphonic acid (AMPA); methylphosphonic acid and its impurities: N-(phosphonomethyl)iminodiacetic acid (PMIDA), N-methylglyphosate, hydroxymethylphosphonic acid and bis-(phosphonomethyl)amine. We evaluated the effect of those compounds on hemolysis, hemoglobin oxidation, reactive oxygen species (ROS) formation and changes in morphology of human erythrocytes. The erythrocytes were exposed to different concentrations of glyphosate and its metabolites and impurities (0.01-5mM) for 1, 4 and 24h. Glyphosate, its metabolites and impurities induced a little hemolysis and hemoglobin oxidation. All changes were very low, even after 24h incubation. Most of the investigated compounds induced reactive oxygen species formation from 0.25mM, except the N-methylglyphosate which caused an increase in ROS formation from 0.5mM. Moreover, the investigated xenobiotics did not change the size and shape (except bis-(phosphonomethyl)amine) of the human erythrocytes. Changes in human erythrocytes were observed only when high concentrations of the compounds were applied. Some investigated metabolites and impurities caused a slight stronger damage to human erythrocytes than a glyphosate. The results clearly show that the changes induced in the erythrocytes can occur only as a result of poisoning with these compounds.