Posted Apr 6, 2023, 10:48 AM
This is a revelation that could cost drinking water distributors dearly. In a report published this Thursday, the National Agency for Food, Environmental and Occupational Health Safety (ANSES) reveals the presence of a metabolite of chlorothalonil, a pesticide banned in France since 2020, in around a third of the water distributed in the country. And this component exceeds the authorized quality limit, making this water non-compliant with regulatory quality criteria.
Chlorothalonil is a fungicide marketed by Syngenta, used in France since the 1970s and banned in Europe since 2020. Degradation residues of this pesticide were found in one out of two samples, and “it leads to exceedances of the limit of quality in more than one out of three samples”.
The presence of metabolite – or degradation product – of this pesticide was not sought until now since the approved laboratories were not able to measure it, reveals Le Monde . “This metabolite was included in this campaign following the publication in 2019 of Swiss data indicating that it was very frequently found in drinking water in Switzerland”, explains ANSES in a press release.
More alarming: “These results show that, depending on their properties, certain pesticide metabolites can remain present in the environment for several years after the prohibition of the active substance from which they originated”, reveals the agency.
The major population pools affected
According to figures released by ANSES, 34% of the French population would be affected. Large, densely populated areas are affected. Asked by Le Monde, the Syndicat des eaux d’Ile-de-France (Sedif) – which serves 4 million users – confirms that more than 3 million of them receive water whose chlorothalonil metabolite content is four five times higher than the regulatory threshold.
The future costs of treating the presence of chlorothalonil metabolite in water are considerable. For example, upgrading the Neuilly-sur-Marne (Seine-Saint-Denis) and Choisy-le-Roi (Val-de-Marne) plants should represent a cost of 870 million euros for return to the compliance zone, indicates the Sedif to the “World”. The possible health effects of these pesticide traces remain unknown.
The ANSES report also reveals the presence of other pollutants in French waters, at much lower concentrations. Metolachlor ESA is present in half of the samples but exceeds the maximum authorized value in only 2% of the waters assessed. Explosive residues were also found in less than 10% of the treated water samples.