Seasonal glyphosate and AMPA levels in urine of children and adolescents living in rural regions of Northeastern Slovenia

Abstract

There are extensive data on the toxicity of glyphosate (GLY) based herbicides (GBH), however the interpretation of some data (e.g. carcinogenic effect) are subject to controversy. For the appropriate health risk assessment more data on exposure levels in the general population, especially in susceptible groups such as pregnant women, the elderly and children are needed. The aims of the present study were to estimate the exposure to GLY and its major metabolite aminomethylphosphonic acid (AMPA) in children and adolescents living in agricultural areas, to identify possible determinants of the exposure, and to assess co-exposure with elements. In total, 149 children (aged 7-10 years, 55% girls) and 97 adolescents (aged 12-15 years; 44% girls) were recruited in 2018 from rural areas of Northeastern Slovenia. The effect of seasonal GLY application on the exposure was estimated using GLY and AMPA levels determined by GC-MS/MS in first morning urine in winter (n = 246) and in late-spring/early-summer seasons (n = 225). Levels of elements were determined by ICP-MS in urine in both samplings and in blood or plasma in the first sampling. Questionnaire data on basic characteristics, dietary habits, living environments and use of pesticides were obtained for all participants. GLY and AMPA were detected in 27% and 50% of urine samples from the first sampling period, respectively; and in 22% and 56% from the second sampling period, respectively. Geometric means and medians of both AMPA and GLY were below or at the limit of quantification (≤LOQ; 0.1 µg/L). Children rather than adolescents tended to have higher exposure, as did, boys rather than girls among adolescents. The exposure did not significantly differ between both sampling periods. Except for one individual, exposure was not higher among participants who reported use of GLY or herbicides in the vicinity of child's home or live in close vicinity of agriculture, orchards, vineyards, gardens, sport courts or cemeteries. The extensive food consumption frequency data revealed higher exposure to GLY and AMPA only among individuals with higher consumption of nuts and wholegrain rice. Levels of AMPA and GLY were significantly positively correlated, with considerably stronger correlation in urine of the second than the first sampling (Spearman's rank coefficient: 0.49 vs 0.22, respectively). Urine levels of As, Pb, Co, Zn and Cu were significantly higher in participants with GLY and/or AMPA levels ≥LOQ than with levels <LOQ. In conclusion, this first estimation of GLY and AMPA exposure in a Slovenian study population showed much lower levels when compared to levels reported in similar studies worldwide. Some results might be explained by more intensive use of GBH in spring, but in general we were unable to distinguish between exposure from the diet or use of GBH in residential environments.

Keywords: Element; Environmental exposure; Exposure sources; Glyphosate; Human biomonitoring; Seasonality.