Pesticides: “Do not run away from tap water”

Pesticides Do not run away from tap water

Could drinking tap water be dangerous for your health? According to data collected by The world from the regional health agencies (ARS), 20% of French people were affected in 2021 by quality thresholds for pesticides being exceeded. Figures revealed this Thursday, September 22, the day of the broadcast of a number of Further investigation on France 2 about it. By way of comparison, only 5.9% of French people were affected in 2020, according to the Ministry of Health.

Among the most affected regions, Hauts-de-France, agricultural territory, with 65% of the population having access to non-compliant water. Julie Mendret, lecturer, authorized to direct research at the University of Montpellier, advocates more sober agriculture and tighter controls to continue consuming tap water.

L’Express: What was your reaction to the data released on Thursday?

Julie Mendret: I had seen it coming for several weeks. Mediapart published other articles which put the chip in the ear. However, I did not expect such a high percentage of exceedance of quality thresholds for pesticides. Last July, I published an article in The Conversation on the drinking water industry where I encouraged the consumption of tap water, rather than bottled. In 2020, non-compliance with drinking water concerned less than 6% of French people, compared to around 20% the following year.

How to explain such a gap in data in one year?

Obviously, this is not a deterioration of the water quality in the meantime. In December 2019, there was an instruction that expanded the list of molecules to be researched by regional health agencies. And the more we look for it, the more we find.

Does this mean that the number of French people concerned could be underestimated?

This figure may be underestimated, as it is possible that there are more metabolites than those quoted. To understand clearly: the control of drinking water is carried out by the agents of the ARS, the problem is therefore the following: each ARS will identify the metabolites to be analyzed according to the local situation, that is to say depending on the type of agriculture that is practiced or the purchases of pesticides in the region. For example, we will control 300 molecules in one region and only about thirty in another.

How to explain the arrival of these pesticides in our tap water?

The areas most affected by water non-compliance are those where intensive agriculture is practiced with heavy use of pesticides. How do these end up in our tap water? The pesticide is a parent molecule and, in the environment, it will undergo degradation, giving rise to intermediates called metabolites.

They are divided into two categories: so-called “relevant” and “irrelevant” metabolites according to the vocabulary used by the National Agency for Food, Environmental and Occupational Health and Safety (Anses), which assesses the genotoxicity of the metabolite and will classify it according to its dangerousness. The metabolite is considered “relevant” if it is capable of causing an unacceptable health risk for the consumer. In this specific case, the limit is 0.1 microgram per liter (µg/l), for “non-relevant” the threshold is set at 0.9. These standards could certainly be reviewed once more scientific knowledge of the effects on health becomes available. These studies take time.

In your opinion, did the authorities fail?

I don’t want to get involved in this field.

What do we know about the dangerousness of these metabolites in water?

There are many metabolites for which the health value is unknown and should not be exceeded. As this is a very recent issue, there are very few studies to assess the dangerousness of these molecules on which we still have very little perspective. On the other hand, it is important to keep in mind that the quantity of molecules that we will absorb via water is still much lower than that which we will ingest via foods not from organic farming. .

What are the solutions to put in place to keep tap water compliant?

First of all, we must work on a preventive measure by promoting more sober agriculture. On the other hand, a curative measure must be put in place by improving treatment channels. In other words, it would be a matter of adding processing steps. Until now, we did not have this general problem of pesticides and the treatment chain was quite rudimentary, so we can consider adding more energy-intensive treatments – which will have an impact on the price of water – but which would eliminate a large part of these molecules, like the membrane process. Processes based on the use of activated carbon also give very good results on pesticides.

Do you continue to encourage the French to drink tap water?

Of course, 80% of tap water meets the standards, which remains satisfactory. I fear that people are turning massively towards bottled water and I invite them to look at the quality of water in their region. Concerning the territories where the regulatory values ​​have been exceeded, I am not going to encourage the inhabitants to consume it, but we cannot imagine that everyone is turning to bottled water. It would be an environmental disaster.

Bottled water has other problems such as the presence of microparticles of plastics and plasticizers for which we have very little experience on the effects on health. For the most vulnerable people, I recommend glass bottled water. One thing is certain: we must not run away from tap water, rather it would take a massive boost to push farmers to turn to organic.


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