PRELIMINARY STUDY FOR THE EVALUATION OF THE HALF-LIFE OF THE HERBICIDE GLYPHOSATE AND ITS METABOLITE AMPA THROUGH BIOMONITORING IN URINE OF EXPOSED FARMERS

Resumo

INTRODUCTION: Glyphosate is a widely used herbicide in global agriculture and in
Brazil, however, several authors have reported various human health issues that may be
related to exposure to glyphosate, particularly in occupationally exposed populations.
Although knowledge about this herbicide is extensive in various fields, glyphosate’s halflife remains under-studied, especially when it comes to determining the optimal timing
for occupational biomonitoring sampling. OBJECTIVE: To detect and quantify
glyphosate levels and its metabolite AMPA in the urine of exposed farmers, using samples
collected at different exposure times. MATERIALS AND METHODS: The study
population consisted of six male volunteer farmers, over 18 years old, from the cities of
Rolante and Riozinho in Rio Grande do Sul, Brazil. Four urine samples were collected
from each volunteer: before glyphosate use (Sample 1), at the end of the work shift
(Sample 2), 24 hours (Sample 3) and 48 hours after the first sample (Sample 4). The
methods used for analysis included derivatization with pentafluorobenzyl bromide
(PFBBr) and liquid-liquid extraction with methyl tert-butyl ether (MTBE). The
equipment used was an Acquity I-Class ultra-efficiency liquid chromatograph coupled
with a triple quadrupole mass spectrometer XEVO TQ-S Micro (CLUE-MS/MS).
RESULTS AND CONCLUSION: In relation to Sample 1, all samples had non-detectable
results, while for the Samples 2, the median found was 4.42 µg/L. The medians for the
third and fourth samples were 1.93 µg/L and 2.82 µg/L, respectively. Two of the study
participants had non-detectable results in all samples, however, one had no direct contact
with the herbicide, and the other used a tractor with a closed cabin for application.
Although this is a preliminary study with a limited sample size, it was possible to observe
the influence of contact and the method used for application, as well as the timing of
sample collection. This provided important information about the rapid elimination of
glyphosate and the best timing for sampling in biomonitoring of herbicide exposure.