Comment on "Glyphosate contamination in European Rivers not from herbicide application?" by M. Schwientek, H. Rugner, S.B. Haderlein, W. Schulz, B. Wimmer, L. Engelbart, S. Bieger, C. Huhn; Water Research Volume 263, 1 October 2024, 122140, page 1-10

“Use of glyphosate – Schwientek et al. carried out a large meta-analysis of sites in Europe and the USA, and noticed differences in glyphosate and AMPA concentration patterns. They hypothesized that the presence of measured concentrations glyphosate and its transformation product AMPA in WWTP effluent cannot be attributed to the use of glyphosate as a herbicide. For this study they used data over the years 2014 until January 2023. The use of glyphosate as a herbicide in urban settings has been banned in some member states of the EU now, but this ban on use by private individuals is a recent development (Belgium 2018, Germany 2021, the Netherlands 2023), so at least would not be visible in large part of their data. Schwientek et al. restrict their analysis of the glyphosate use in Europe to the comparison of glyphosate sales for non-occupational use between 2014 and 2020/2021 in Berlin. However, in Germany the total sales of glyphosate were 4315 tonnes in 2015, 4700 in 2017, 3058 in 2019 and 4097 in 2021 (Wehde, 2023), which does not indicate a large decrease. Citizens and/or municipalities will have continued to use glyphosate as long as it could be legally bought, and probably will have kept some supplies for later use. Therefore, it is to be expected that glyphosate will have been used on roads and railways during most of the period studied. Grandcoin et al. (2017) and Botta et al. (2009) have shown that this application results in high glyphosate concentrations in WWTP effluent through storm sewers, contrarily to the assumption made by Schwientek et al.. This, however, is in accordance with the conclusion drawn by Schwientek et al., that municipal wastewater treatment plants significantly contribute to the release of AMPA and glyphosate.
Polyphosphonates are used in several industrial and household applications, and in water treatment processes (Studnik et al., 2015; Grandcoin et al., 2017), but only 15 % of the polyphosphonates originates from detergents. Even if these compounds would be converted into glyphosate on a significant scale, this could still not account for the concentration differences observed by Schwientek et al.”

(Citation: Tolkamp, H.H., Hofman-Caris, C.H.M. – Comment on “Glyphosate contamination in European Rivers not from herbicide application?” by M. Schwientek, H. Rugner, S.B. Haderlein, W. Schulz, B. Wimmer, L. Engelbart, S. Bieger, C. Huhn; Water Research Volume 263, 1 October 2024, 122140, page 1-10 – Water Research 272(2024)art. no. 122965 – DOI: 10.1016/j.watres.2024.122965)

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