Very used on corn crops, the S-Métolachlore breaks down into by-products responsible for a vast pollution of French phreatic tablecloths.
by Stéphane Foucart
At the origin of a large-scale contamination of French water tables, the S-Métolachlore herbicide will see its main uses prohibited in France. The National Agency for Food, Environmental and Labor Health Safety (ANSES) announced it on Wednesday, February 15, drawing the consequences of its expertise work indicating that three degradation products (or “metabolites “) This pesticide is found in groundwater at concentrations” greater than the quality limit set by European legislation “. Authorized since 2005, the product, of which around 2,000 tonnes are spread each year in France, is marketed by the agrochemist Syngenta. Six months’ grace deadlines for sale and one year for use should support these prohibitions, according to the agency.
In September 2021, ANSES had made a report examining all the data for contamination of groundwater, surface water and waters intended for human consumption. “The exhaustive examination of the available data has shown a fairly ubiquitous presence, all metabolites [of the S-Metolachlore] combined, in all aquatic compartments, it is explained to ANSES. There was contamination of the resource At unacceptable levels with regard to the regulations, that is to say above 0.1 µg/L [0.1 microgram per liter]. But this without a notion of associated risk for consumers. “
At the end of this expertise, the Maisons-Alfort (Val-de-Marne) agency hardened the conditions of use of herbicide, reducing the maximum application doses for corn, sunflowers , soybeans and sorghum. The measure has not made it possible to see the metabolites incriminated to return under the regulatory threshold in the tablecloths, the ANSES has decided to take prohibition measures. These are ahead of the conclusions of the European Food Safety Authority, which should be rendered in the coming weeks and could lead to a refusal to reautorize this substance in the European Union.
criterion of ” Relevance “
Obviously, the days of the S-Métolachlore are counted on a community scale. Not only does its degradation products accumulate in the groundwater, but it is itself classified “suspected carcinogenic” since June 2022. As a result, its three main metabolites (ESA-Métolachlore, Noa-Métolachlore, Oxa-Métolachlore) are deemed “relevant”, that is to say potentially problematic, with regard to regulations on pesticides in groundwater. This criterion of “relevance” makes the presence of these three metabolites unacceptable in the tablecloths beyond 0.1 µg/l.
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