S-Metolachlor Metabolites: How ANSES Artificially Eliminates Almost All Metolachlor Drinking Water Noncompliance Situations ESA

S-Metolachlor Metabolites: How ANSES Artificially Eliminates Almost All Metolachlor Drinking Water Noncompliance Situations ESA

Générations Futures condemns a valuation method that ignores the precautionary principle

According to data from the Ministry of Health for 2020[1], 1,640,318 people in France were affected by a non-compliance with drinking water related to the presence of a metabolite of S-metolachlor (a herbicide used in particular on field crops), ESA-metolachlor. However, according to the ministry, the presence of ESA Metolachlor in drinking water was responsible in 2020 for 51% of distribution unit non-compliance cases. 75% of the population affected by these discrepancies was affected this year due to the presence of ESA-metolachlor. It is clear that the ESA’s metolachlor is one of the main pesticide metabolites responsible for exceeding drinking water quality limits.

But rest assured, that was before! Through remarkable sleight of hand by ANSES (National Agency for Food Safety and Health), the minimum ESA metolachlor content to determine that water is non-compliant just passed on September 30th from 0.1 µg/L at 0.9 µg/L[2] ! Thus, according to our initial estimates from the analysis of the SISE-eaux data[3], 97% of distributed water declared non-compliant after exceeding the metolachlor ESA quality value will become “compliant” again.

How is it possible ? We explain to you:

A brief history of the management of pesticide metabolites in drinking water

The European Directive on the quality of water intended for human consumption set a quality limit of 0.1 µg/L for pesticides and their metabolites in the 1980s. This directive is included in France in the Public Health Code. Thus, if a “conforming” pesticide or metabolite exceeds this value of 0.1 µg/L, the water is declared noncompliant and action must be taken to restore water quality as quickly as possible. Until 2020, because the notion of relevance was not clearly defined, all metabolites were considered “relevant” by default. Therefore, the quality limit of 0.1 µg/L applies to all metabolites.

The numerous observed exceedances of this 0.1 µg/L value, as metabolites are better sought after in drinking water, prompted authorities to define exactly what the corresponding metabolite is. The relevant metabolite is therefore defined as the metabolite for which “it must be considered that it can generate (itself or its processed products) an unacceptable risk to the health of the consumer” Thus, ANSES developed a methodology to assess metabolite relevance and identify “relevant” metabolites and “irrelevant” metabolites.[4].

For all metabolites considered irrelevant after this assessment, the quality value of 0.1 µg/L no longer applies following the publication in December 2020 of an instruction by the Directorate General of Health (DGS)[5]. Instead, another so-called “vigilance” limit applies and is set at 0.9 µg/L. Thus, following this instruction from the DGS, water is always considered compliant when the so-called “inappropriate” metabolites exceed the value of 0.1 µg/L, without exceeding 0.9 µg/L (see the explanatory diagram in the appendix to this document) . Thus, part of the problem with metabolites in drinking water is artificially eliminated.

This is exactly what happened to 2 metabolites of the pesticide S-metolachlor, ESA metolachlor and NOA metolachlor. An ANSES opinion was published on 30 September 2022[6]secret in which experts have re-evaluated the relevance of these metabolites and now consider them “irrelevant”.

The consequences of this downgrading of ESA-metolachlor from relevant to non-relevant are significant:

  • As we have seen, ESA metolachlor is one of the most abundant metabolites found in drinking water. The majority of waters declared noncompliant in 2020 were due to ESA metolachlor. By now treating this metabolite as irrelevant, instances of non-conformity with drinking water will be greatly reduced. According to our analysis of the 2020 SISE-EAU database, 1,752 distributed water analyzes were found to be above the 0.1 µg/L standard for ESA metolachlor, of which only 54 were above the 0.9 µg/L standard valid for ESA metolachlor.
  • This downgrade as inappropriate also has implications for the management of raw water (groundwater or surface water) used for drinking water production. In these raw waters, quality standards of 2 µg/L no longer apply to inappropriate metabolites. Thus, if the raw water contains ESA metolachlor at a level higher than 2 µg/L, it can still be used for the production of drinking water without applying for a use permit to ANSES as required for the respective metabolites.

But then how does ANSES continue to assess the relevance of metabolites? DGS qualifies the ANSES method as “robust scientific expertise”. This is enough to make sure of the reliability of the method! But what is it really? Is this assessment based on toxicology studies? Does the precautionary principle apply?

To assess the relevance of metabolites, ANSES experts will consider several data on their toxicity.

Genotoxic potential is first assessed. For this assessment, ANSES applies the precautionary principle, taking into account that a given metabolite is relevant when genotoxicity data are lacking or when existing data are in doubt. Thus, the ESA metabolite metolachlor was considered relevant until then because the existing data, coming exclusively from the manufacturers, showed “ambiguous” results and had too many gaps in their protocol. New data were requested and provided by Syngenta as part of the re-evaluation of the marketing dossier. With these new data from November 2021, ANSES considers that the main concerns of the old studies have been “resolved”. Thus, metabolites are no longer considered relevant, as there will no longer be any doubt that they are not genotoxic.

The other points that ANSES evaluates to assess the significance of a metabolite are carcinogenicity, reprotoxicity and endocrine disrupting potential. For these points, err on the side of caution when no data is available! Here, in contrast to the approach used for genotoxicity assessment, metabolites were considered irrelevant until data did not exist ! In other words, we don’t know anything about their potential long-term effects, but we still think they’re irrelevant. Very practical to limit the exceedance of quality standards, but not very protective for the population who are exposed to these substances on a daily basis and for several years for some!

This unprotected approach is not questioned by ANSES experts although there are many warnings about the carcinogenic and reproductive toxic potential of the parent molecule, S-metolachlor ! In fact, the European Chemicals Agency (ECHA) has just classified S-metolachlor as a suspected carcinogen.[7]. However, regulations on the marketing of pesticides require that, when an active substance is suspected to be carcinogenic, it must be proven by research that the metabolites themselves are not. However, this classification does not create doubts or problems for the ANSES experts who write: ” Acceptance of this conclusion at the end of the active substance re-evaluation procedure would not justify classifying the metabolite as relevant. “.

Thus, although there are no data on the metabolites and while the parent substance is suspected to be carcinogenic, ANSES nevertheless confirms ” that there is no reason to believe that they could create an unacceptable risk to the health of the user “.

This is what ” solid scientific expertise » experts from ANSES, whom we strongly condemn today! Although the classification of S-metolachlor as a suspected carcinogen should have led to the strengthening of measures to monitor and protect populations exposed to its metabolite, on the contrary, we note a weakening of the measures taken by the authorities.

It is recalled that a health value was established by ANSES for ESA metolachlor at 510 µg/L. However, as described in our previous report[8], this value is based on a very limited number of studies and no chronic studies. Therefore, the reliability of this value also raises questions.

Therefore, the precautionary principle is not really suitable for the evaluation of pesticide metabolites. This is far from the original spirit of the European directive, which, it must be remembered, had set this limit value of 0.1 µg/L in order to protect the resource. However, the DGS guidance of December 2020 reminds us well: “ The legislator has believes that these molecules should not be present in EDCH. This is the reason for which he set the quality limit at 0.1 µg/L, which is equivalent to “absence in water” from these pollutants. […] This single value for EDCH would reduce the overall usage of pesticides and thus indirectly protects water resources. »

As we can see, the issue of pesticide metabolites in water is not over. Générations Futures intends to monitor it closely and act – legally if necessary – to end an unacceptable health and environmental situation.


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