Chlorothalonil, a pesticide banned since 2020, was found in excessive quantities in a third of drinking water in France, according to ANSES analyzes published on April 6, 2023. Is it dangerous?

When one seeks, one finds. This is evidence of the contamination of a third of drinking water in France which was discovered and revealed in the report of the National Agency for Food, Environmental and Occupational Health Safety (Anses) , published Thursday April 6, 2023. During its last national analysis campaign carried out both in mainland France and overseas to assess the presence of 157 pesticides and metabolites in tap water, the organization visited account that “89 of them were detected at least once in raw water and 77 times in treated water”. Among them, one substance caught the eye: R471811 or metabolite of chlorothalonil.

This pesticide is one of seven compounds present in excess of the 0.1 µg/litre limit imposed by the drinking water quality criteria. Found in 34% of the water samples studied, chlorothalonil is “the most frequently found pesticide metabolite”, warn ANSES researchers.

ANSES’s observations are cause for concern, because the metabolite in question comes from chlorothalonil, a fungicide which was banned in 2019 and applied in France in 2020. The pesticide used for years and still present in soil since its ban has deteriorated and contaminated drinking water. “Certain pesticide metabolites may remain present in the environment for several years after the banning of the active substance from which they are derived”, underlines the ANSES press release in its conclusions.

Classified as a “relevant” pesticide, chlorothalonil can be present in water but must not exceed the threshold of 0.1 µg/litre. If the quantity of this substance exceeds this limit then the quality of the water deteriorates. On the other hand, ANSES specifies that “the water quality limit for pesticides does not in any way constitute a risk threshold for the health of consumers because it is not developed on the basis of the toxicity of the substances” . If health risks are not guaranteed for the moment, Le Monde writes that the parent molecule of the metabolites detected in drinking water is “considered as a probable carcinogen by the European health authorities and associated with the appearance of kidney tumors in animals. laboratory”. The risk is therefore present. As it stands, “no health effect of the metabolite in question has been proven at these exposure doses, but the data are very incomplete”, further specifies the evening newspaper.

In 2019, when the marketing and use of chlorothalonil was decided, the European Commission indicated that it was “impossible to date to establish that the presence of metabolites of chlorothalonil in groundwater will not have harmful to human health” recalls Liberation. The European Food Safety Authority believes that the pesticide should be considered a “suspected carcinogen”.