Residues of glyphosate and aminomethyl phosphonic (ampa) in genetically modified soybean

Abstract

Successive and arbitrary application of glyphosate may cause cases of intoxication in humans by indirect ingestion, since transgenic soybeans present levels above the permitted for this herbicide. The objective of this study was to evaluate the glyphosate and aminomethyl phosphonic acid (AMPA) levels in genetically modified soybeans tolerant to glyphosate. The chosen experimental design was composed by random blocks of eight treatments and four replications. Treatments consisted in glyphosate, applied only once and singly in doses of 720 and 960 g a.i. ha^-1, glyphosate at 720 and 960 g a.i. ha^-1 in mixtures, respectively, with com chlorimuron-ethil at 10 g a.i. ha^-1, sequential applications of glyphosate in doses of 720/720; 960/720; 960/720/720 g a.i. ha^-1 and a control group weeded throughout the entire cycle. The samples were analyzed by high efficiency liquid chromatography (HELC). Evaluated characteristics were: residue levels (mg kg^-1) of glyphosate and its metabolite AMPA. The highest glyphosate residue level found in the soybeans was 0.92 mg kg^-1, less than the highest permitted, which is 10.00 mg kg^-1. Residues of AMPA were also found, with the highest level being 1.53 mg kg^-1, indicating glyphosate metabolization.