No alert at this stage, but increased vigilance. Residues of a pesticide that has been banned in France since 2020, chlorothalonil, are ubiquitous in drinking water. About a third of the water distributed in France does not comply with the regulations, according to a report made public Thursday, April 6 by the National Agency for Food, Environmental and Occupational Health Safety (Anses).
ANSES studied water samples in all departments, including overseas, in particular looking for 157 pesticides and their metabolites, that is to say the components resulting from their degradation. The case of the metabolite of chlorothalonil R471811 has particularly attracted the attention of experts in this exploratory research work. This fungicide is the most frequently found, “in more than one in two samples”, notes ANSES. Above all, just over a third of the samples taken (34%) exceeded the quality threshold, set at 0.1 microgram (µg) per litre.
“The Underside of the Iceberg”
These higher concentrations did not “surprise” the NGO Générations Futures. As early as 2006, the European Commission had indeed indicated that chlorothalonil had the capacity to produce metabolites in large quantities. “We know well before they are placed on the market that these substances will degrade into metabolites and that these will migrate into the groundwater,” said Pauline Cervan, toxicologist at Générations Futures, to L’Express.
As explained by ANSES, “the contamination of water resources by all of these products is linked to their entrainment by runoff or by infiltration towards surface and underground waters respectively”. In addition, “this transfer of pesticides and pesticide metabolites to water resources is influenced by their physico-chemical properties (water solubility, stability), by the nature of the soil, or even by rainfall”.
“This is a problem raised for a long time by associations”, reacts to L’Express François Veillerette, spokesperson for Générations Futures. “As long as we weren’t looking for the metabolite R471811, we couldn’t find it. When we start looking for it, it’s ‘panic on board’ because we realize that it’s everywhere”, he adds, before warning: “This is only the beginning of the discoveries, it is the submerged face of the iceberg.” “When we look for perfluorides in drinking water, we will have surprises”, abounds Pauline Cervan.
Marketed in 1970 by the German Syngenta, chlorothalonil is no longer on the market. The European Commission had not renewed the authorization of this fungicide in 2019, and France had granted a grace period until May 2020 for the disposal of stocks of the product. “They waited so long before doing research that the molecule even had time to be banned before they started looking for it,” squeaks François Veillerette.
If chlorothalonil was not researched until very recently, it is mainly because not all approved laboratories were able to measure it. “We are finding these pesticides more and more because the methods of analysis are progressing and we are looking for them more and more. But maybe we were in denial”, advances to L’Express Julie Mendret, lecturer at the University of Montpellier, specialist in water treatment.
On the side of ANSES, we recognize “looking for products that we do not know very well”. “We often know less well the products of degradation than the active substances”, explains to L’Express Christophe Rosin, head of the water chemistry unit at the Anses hydrology laboratory. This chemist, coordinator of the report, notes that it “should be better to characterize the level of exposure of the population through drinking water”. The idea is therefore to have “a finer map” of this pesticide in surface and ground water in mainland France.
Health risks? “We do not know anything”
ANSES does not want to alarm the public about the health risks. “We are not making a shortcut by saying that a third of the population is exposed”, underlines Christophe Rosin. In 2019, Brussels specified that it was “impossible to date to establish that the presence of metabolites of chlorothalonil in groundwater will not have harmful effects on human health”.
The European Commission quoted the conclusions of the European Food Safety Authority. The EFSA considered that chlorothalonil “should be classified as a category 1B carcinogen”, that is to say a “suspected” carcinogen. ANSES took up this argument in a note published in January 2022, recalling that studies on chlorothalonil had identified “kidney tumors in rats and mice”. ANSES had classified R471811 “relevant”, that is to say potentially problematic. It could therefore create an unacceptable health risk for the consumer.
R471811 “is classified as ‘relevant’ due to the lack of information concerning this metabolite”, notes Christophe Rosin. For Pauline Cervan, this is a “default classification”. No long-term study on its health effects exists. “We don’t know anything about it,” laments Pauline Cervan. The toxicologist regrets that the only mandatory studies relate to the genotoxicity of a substance, that is to say its ability to damage DNA, one of the mechanisms responsible for carcinogenesis. “Relying on genotoxicity to assess the health risks of a substance is toxicological nonsense,” she says.
For each product, a provisional health threshold below which no restriction is immediately provided for is established. The transitional health value set for R471811, 3 µg/l, has never been exceeded in the water distributed, according to data collected by ANSES. “The water sampled and analyzed is thus non-compliant but does not present a health risk”, reassures the Ministry of Ecological Transition and Territorial Cohesion.
Pauline Cervan recalls that this value of 3 µg/l was set by the German health authorities. They “used a technique which consists of extrapolating data from other substances”. This scientific method is “very controversial” and “very approximate”, according to the toxicologist. “We assume that all substances that are not genotoxic do not pose a problem below 3 μg / l. It is very limited”, regrets the doctor of pharmacy. According to her, this scientific approach “does not take into account the effects of endocrine disruptors or even carcinogenic effects unrelated to genotoxic effects”. But it allows to “reassure” the population. Until when ?
Bottled water not completely spared
Asked by The world, a manager of a public operator, who requested anonymity, fears that it is “impossible to explain to people that their water does not comply with quality criteria, but that it is drinkable”. Will the population massively turn to bottled water? “Pesticide contamination of bottled water may be less than tap water, but it is not non-existent,” warns Julie Mendret.
For the water treatment researcher, “the only sustainable model is that of the tap”. “Bottled water is an environmental disaster,” she said. Pauline Cervan does not say otherwise: “Plastic water is not at all the solution. The solution is not to pollute the water and to act upstream.”
NGOs and players in the sector point out that metabolites take a very long time to disappear from the environment, sometimes decades. “Depending on their properties, certain pesticide metabolites may remain present in the environment for several years after the banning of the active substance from which they are derived”, notes ANSES.
This is the case of atrazine, a herbicide banned in the early 2000s, whose metabolites are still found in water. “According to scientific studies, it will take at least ten years from the date of prohibition of S-metolachlor (Editor’s note: an agricultural herbicide) for the metabolites to disappear”, observes Pauline Cervan.
The need to strengthen treatment channels
As noted The world, one of the alarming points is that conventional treatment channels are unable to get rid of this type of pesticide. It is possible to strengthen the treatment channels. Problem: the technologies to be implemented to fight against the metabolite – activated carbons, nanofiltration and/or reverse osmosis (a filtration technique) – are particularly expensive and energy-intensive. And, finally, the user will no doubt be involved. “Activated carbons consume less energy but all these processes are energy-intensive while we are in a context of energy savings”, specifies Julie Mendret.
“France should implement massive investment plans in drinking water production plants, in sanitation stations and in the search for techniques to eliminate these substances, says Pauline Cervan. We’re waking up.”
“The results of this report call for continued work to improve water quality, particularly water intended for human consumption. This calls for intensified measures to protect catchment areas, adapt and differentiate them according to territorial specificities”, comments for its part the Ministry of Ecological Transition and Territorial Cohesion.
The government explains that the Ministry of Health will put in place, under the guidance of the Regional Health Agencies (ARS), “more regular measures, from 2023, of chlorothalonil and its metabolites, in connection with the rise in skills of approved laboratories for the sanitary control of water to provide reliable results”. On the side of ANSES, we still want to reassure: “Drinking water is very controlled”, underlines Christophe Rosin.