The health security agency published a study on Thursday on the presence in tap water of chemical compounds little or not sought after during regular checks. In particular, it draws attention to the metabolite of chlorothalonil R471811, a fungicide banned for several years and whose residues have been found “in more than one out of two samples”.
It may be transparent, but the water we drink hides things. The National Agency for Food, Environmental and Occupational Health and Safety (ANSES) published a report on Thursday 6 April on the“water intended for human consumption”. ANSES took a particular interest in “the presence of chemical compounds which are not or little sought after during regular checks”. This study concerns samples of raw and treated water, carried out throughout France, including overseas. The results from some 136,000 analyzes carried out show widespread contamination with pesticide residues, even years after their use.
The residue of a banned fungicide is ubiquitous in drinking water and exceeds the quality limit in a third of cases
Before carrying out the survey, ANSES retained 157 pesticides and pesticide metabolites, that is to say the residues of these pesticides. In total, “89 of them were detected at least once in raw water and 77 times in treated water”notes the health security agency.
For seven compounds, the analyzes revealed “exceedances of the quality limit of 0.1 µg / liter”. “A particular case stands out”, according to ANSES: that of the metabolite of chlorothalonil R471811. The latter comes from the degradation in the environment of chlorothalonil, a fungicide banned in France since 2020, but long used in many crops (vines, cereals, potatoes), according to an ANSES phytopharmacovigilance sheet dated 2017. It caught the attention of the health security agency because it is the pesticide residue found most frequently, “in more than one out of two samples”and that it led to exceedances of the quality limit “in more than one out of three samples”.
“These results show that, depending on their properties, certain pesticide metabolites can remain present in the environment for several years after the banning of the active substance from which they originated.”
ANSESin a scientific and technical support report published on April 6, 2023
The European Commission had not renewed the authorization of chlorothalonil in 2019. France then granted a grace period until May 2020 to allow stocks of this product to be sold off. Brussels noted, at the time, that it was “impossible to date to establish that the presence of metabolites of chlorothalonil in groundwater will not have no harmful effects on human health”. The Commission took up the conclusions of the European Food Safety Authority, which wrote, in April 2019, that chlorothalonil “should be classified as a category 1B carcinogen”i.e. carcinogenic “Assumed”.
The residue of a herbicide, already in the viewfinder of the health authorities, detected in more than half of the samples
ANSES also points to the presence of another pesticide metabolite, metolachlor ESA, in more than half of the samples taken. It is a residue of S-metolachlor, “a herbicidal active substance of the chloracetamide family”Who “enters into the composition of various herbicides”explained ANSES in a September 2021 report. S-metolachlor, with 1,946 tonnes sold each year, is “one of the most widely used herbicidal active substances in France”, notes ANSES. The health security agency, mandated to evaluate and authorize or not pesticides, had also initiated a procedure for the withdrawal of this herbicide widely used on corn, soybeans and sunflowers. But the Minister of Agriculture, Marc Fesneau, asked ANSES to back down, on behalf of the “food sovereignty”.
>> Agriculture: we explain the controversy surrounding S-metolachlor, this herbicide that the government is trying to save
The metolachlor ESA residue is under close monitoring. “This metabolite does not meet any of the conditions allowing it to be concluded that it is not of concern”, noted ANSES in an opinion of January 2023, requiring a more in-depth assessment in order to find out more. S-metolachlor has also been classified as a carcinogen and endocrine disruptor. “suspected” in June 2022 by the European Chemicals Agency (Echa). No need to worry despite everything, underlines ANSES.
“All the concentrations measured for the different molecules remain, however, much lower than the Vmax [les valeurs sanitaires maximales] when these are available.
ANSESin a scientific and technical support report published on April 6, 2023
The Agency calls for vigilance and considers that “this work should make it possible to develop the list of molecules included in the context of sanitary control of water in order to improve its relevance”.
Because the problem is not new. The presence in drinking water of pesticide or drug residues has been documented for many years. Studies and analyzes take place on an ongoing basis. Health authorities talk about it regularly. The High Council for Public Health (HCSP) recalled “the need to strengthen preventive measures aimed at reducing contamination, by pesticides and their metabolites, of raw water resources used for the production of water intended for human consumption” in a notice from March 2022 (in PDF).
Explosive residues in less than 10% of samples
In France, the contamination of drinking water by explosive residues is a consequence, already known, “of the two world wars of the 20th century, and more particularly of the first (1914-1918)”explains ANSES, stating that “Military activities (manufacture of ammunition, combat zones, destruction zones) have resulted in potential environmental pollution of a great chemical diversity”. To establish a more precise inventory, the national sampling and analysis campaign therefore focused on “different organic compounds constituting the munitions of the two world wars”. In total, 54 molecules were searched.
The results show around sixty positive sites, all over France, but for different reasons. In areas “historical”Hauts-de-France and Grand-Est, it is a “high concentration of molecules of the TNT family, such as sites corresponding to battles in the Great War or demolition sites after the First World War”.
The health security agency also points to New Aquitaine and Occitanie “contamination by so-called ‘modern’ explosives such as HMX and RDX, used since the Second World War which are still found in current explosive compositions”. In any case, the levels measured are not of concern, assures ANSES.
Minute traces of a carcinogenic solvent, 1,4-dioxane, in 8% of the samples
1,4-dioxane is classified as a category 2B carcinogen by the International Center for Research against Cancer, recalls the National Institute for Research and Safety (INRS). Its release into the environment is primarily related to waste disposal practices chemicals or waste water discharges”, explains ANSES. Dioxane, listed by the INRS, can be used in the manufacture of other basic organic chemicals, basic plastics, soaps, detergents and cleaning products, chemicals for industrial use, paint, varnish or even inks.
Traces of dioxane were found in 8% of the samples taken by the health security agency as part of its study. Although European and national regulations do not provide for a regulatory value for 1,4-dioxane in water intended for human consumption, there is no need to worry as the levels measured are low. The quality criterion for drinking water is set at 50 µg/L by the World Health Organization (WHO). In France, the maximum concentration observed in raw water is 4.8 µg/L. It should also be noted that the detection threshold was extremely low (set at 0.15 µg/L) and that, in 92% of cases, this threshold was not exceeded.