French drinking water threatened with non-compliance by an eternal pollutant

French authorities and water managers are at the dawn of an unprecedented situation: a majority of French people could soon find themselves with drinking water that does not meet quality criteria. The fault of a molecule, trifluoroacetic acid (TFA), an “eternal pollutant” today unregulated, and with poorly documented health effects, which contaminates water resources in France and Europe.

The TFA found in water comes from the degradation of a pesticide, flufenacet. Used mainly for the treatment of cereal crops (wheat and barley in particular), flufenacet is one of the best-selling herbicides in France. Its sales almost doubled between 2019 and 2022 (latest year for which data is available) to reach more than 900 tonnes per year.

However, on September 27, flufenacet was recognized as an endocrine disruptor by the European Food Safety Authority (EFSA). This reclassification should automatically lead the French authorities to now consider TFA as a “relevant” metabolite for drinking water – that is to say potentially dangerous. Indeed, according to the procedure put in place by the French Agency for Food, Environmental and Occupational Health Safety (ANSES), as soon as an active substance is an endocrine disruptor, its metabolites must be considered by default as “relevant”, therefore subject to a threshold not to be exceeded.

This limit is set at 0.1 microgram per liter (µg/L). Beyond this concentration, although without a proven health risk, the water is declared “non-compliant”. According to the public health code, communities can obtain an exemption to distribute non-compliant water to users for three years. As the legislation stands, this exemption is renewable only once: after six years, the water must become compliant again in order to be distributed.

Bottled water is not spared

According to modeling carried out by ANSES on behalf of EFSA as part of the flufenacet evaluation file, we have known since 2017 that the degradation of the herbicide leads to TFA concentrations of up to 10 µg/L , up to a hundred times higher than this limit. The Pesticide Action Network (PAN) Europe carried out drinking water samples in around ten European Union (EU) countries including France between May and June: the compliance limit was exceeded in 86% of cases and in three out of four water samples tested in France. A sample taken from the tap water which supplies a third of Paris notably revealed a level greater than 2 µg/L, or twenty times higher than the quality threshold.

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