The alert was launched by Switzerland, where one in three measuring stations is concerned.
An ANSES report published on Thursday shows it: in France too, drinking water is largely contaminated with residues of chlorothalonil, a fungicide marketed by the agrochemical giant Syngenta and banned in France since 2020.
Every three years, the hydrology laboratory of the national health security agency carries out campaigns to measure the presence in drinking water of chemical compounds which are not or little sought after during regular checks.
This latest report thus analyzes the presence of more than 157 pesticides and pesticide metabolites (in other words components resulting from the degradation of plant protection products), 54 explosive residues (mainly from weapons sites dating from the First World War ) and a solvent (1,4-dioxane).
A campaign conducted throughout France - including overseas - which collected more than 136,000 results via samples of raw or treated water.
Read alsoPesticides: is tap water a health risk?
Of the 157 pesticides searched, 89 were detected at least once in raw water and 77 times in treated water.
But two compounds were quantified in more than 50% of the samples, and
“one case in particular emerges
”, indicates ANSES: that of the metabolite of chlorothalonil R471811.
On the one hand, “
it is the most frequently found pesticide metabolite, in more than one out of two samples
”;
on the other hand, “
it leads to overruns of the quality limit (0.1 µg/litre) in more than one out of three samples
”.
However, the agency notes that no excess of “
Maximum health values
” (Vmax, the substance-specific health safety limit) has been observed.
By banning chlorothalonil in 2019, the European Union classified it as a Category 1B carcinogen (with “suspected” human carcinogenic potential).
“
It is impossible to date to establish that the presence of metabolites of chlorothalonil in groundwater will not have harmful effects on human health or unacceptable effects on said waters, can we thus read in the
document fungicide ban
.
(...) In addition, the Authority could not exclude a genotoxicity problem concerning the residues to which consumers will be exposed and highlighted the existence of a high risk for amphibians and fish for all the uses assessed.
"Anyway, the
certain pesticide metabolites may remain present in the environment for several years after the prohibition of the active substance from which they are derived
”.
Another pesticide in the viewfinder
Another pesticide metabolite caught the attention of ANSES: metolachlor ESA, also detected in more than half of the samples, even though less than 2% of them exceeded the management value of 0.9 µg/ liter defined for so-called "irrelevant" metabolites (which at this stage do not require the same vigilance and the same regulatory measures as an active substance found in tap water).
This value "
aims to ensure that exposure to these substances throughout life does not present a risk to the health of consumers"
, recalls the agency.
However, this result is far from trivial: last February, ANSES announced that it wanted to ban the main uses of S-metolachlor, "
the
», essentially in corn, sunflower and soybean crops.
But in recent days, the Minister of Agriculture Marc Fesneau asked the Agency to reconsider this decision, the herbicide in question still being authorized within the European Union.
Read alsoMicropollutants infest our rivers
The results of ANSES's work "
may be useful to those responsible for the production and distribution of water to build their water quality monitoring program and to regional health agencies to complete their health control programs
“
,
concludes ANSES in a press release.
