► What are we talking about?
In mid-September, the “Complément d’Enquête” program and the daily The world alerted on the levels of pesticides and metabolites in tap and drinking water. The water quality thresholds were exceeded in nearly 9,000 French municipalities, mainly in the North and in Brittany. From 6% in 2020, the rate of French people concerned by water “outside the nails” rose to 20% in 2021.
This jump does not correspond to a sudden rampant consumption of pesticides, but simply to a better knowledge of chemical inputs and their effects. In the line of sight, metabolites, molecules resulting from the degradation of pesticides in natural environments.
► What is the problem?
Metabolites are classified into two categories: relevant or irrelevant, depending on the potential effects on human health. For “relevant” metabolites, the French authorities have set a threshold at 0.1 µg/L per molecule and 0.5 µg/L for the sum of the molecules. For the “non-relevant”, this threshold is 0.9 µg/L. ANSES points out that these values are not established on the basis of the health hazard, but simply to be as low as possible: “The choice of European standards for pesticides is based on an Alara-type position, that is to say “As Low As Reasonably Achievable” », which can be translated as “as low as reasonably achievable”.
To determine the exact health risks, ANSES establishes “maximum health values” (Vmax). For now, about 200 molecules have a Vmax, but the number of metabolites and molecules is much larger, and the health agency is continuing its work. There may therefore be metabolites which exceed the precautionary threshold – and it is these overruns which are recorded – but without ever reaching the health threshold, simply because the latter does not exist.
► Has the government really contented itself with raising the thresholds?
With regard to two metabolites, metolachlor NOA and metolachlor ESA, ANSES initially considered them to be “relevant” during its opinion in 2021 in the name of the precautionary principle. The document explained that “the doubt relating to their mutagenic and/or genotoxic potential cannot be removed, the regulatory quality limit of 0.1 µg/L must be applied”.
At the end of September, a new opinion and a change of tack: ANSES now considers these two molecules as “non-relevant”. These results are based on data provided by the Swiss manufacturer Syngenta, which manufactures the pesticides responsible for these metabolites. For metolachlor NOA, ANSES thus notes «regret carrying out an in vitro test, rather than an in vivo test, which would have been more relevant» et “the lack of interpretation of the results of the new test with regard to the previous one, the results of which were equivocal “. And for both, the opinions still point out that, if the original pesticide were to be classified as an endocrine disruptor at European level, where its re-approval is in progress, “it will be necessary to reassess the ranking of relevance”.
In other words, the opinions could in the future return to the side « pertinent ». In the meantime, the threshold for water quality is raised to 0.9 µg/L for these molecules. A «sleight of hand “, denounces the Future Generations association, which militates against the use of pesticides and according to which “Cases of drinking water non-compliance will decrease considerably” with this change, especially regarding metolachlor ESA. If we take the town of Concarneau (Finistère) as an example, none of the 19 exceedances recorded over the last eighteen months would have been noted.