Contamination of tap water by a pesticide: should we be worried?

A third of drinking water in France tested by the national agency for food, environmental and occupational health and safety (Anses) is contaminated with a pesticide residue. According to the agency, among the pollutants scrutinized, the metabolite of chlorothalonil has caught the attention of researchers. What does a metabolite mean? This means that it comes from the degradation of an active substance, in this case the pesticide, which will in reality generate one to several molecules which will degrade in the environment by the effect of rain, runoff, then will reach underground environments, in groundwater, or even in rivers. That’s why we find it in our faucet.

>> What we know about pesticide residues in tap water in thousands of municipalities (and uncertainties about their toxicity)

Chlorothalonil was a pesticide used for 50 years before being banned in 2020 in France because it was probably carcinogenic. In 2017, this molecule was used in 39 products for around fifty uses, which ranged from the treatment of cereals such as wheat, barley, rye, and even on vegetables such as tomatoes, cucumbers or even onions, carrots or melons. So, in reality, it is scattered everywhere.

Switzerland discovers this pesticide in its waters in 2013

In fact, in 2013, Switzerland discovered the presence of chlorothalonil completely by chance. She will carry out an investigation for several years and will discover at that time that this famous R471811, the one we are talking about today in France, is in much higher concentration even than before. Nearly 60% of the concentration is found in all taps in Switzerland: two thirds of our Swiss neighbors are directly affected by this molecule. The authorities then asked farmers to massively stop using this pesticide, except that it is still present in the land. Switzerland today finds itself in a rather special situation, having to try to fight against it without talking about it and despite everything by increasing the water bill by 75% in order to treat the water with much more expensive means. And it is the consumer who pays in Switzerland when in reality it would be much more logical for it to be the polluter.

Should we worry about our tap or our plate since these products are put directly on our consumer products? One solution: eat organic on a global scale. A study, carried out in November 2017 and published in Nature, highlights the fact that we could feed the entire world population with organic products. But that would require a lot more land to cultivate, and therefore we would participate a little more in deforestation. Unless we play on two elements: food waste, and the reduction of our share of meat on our plate since 70% of the land in Europe is manufactured to make cereals, which are then transmitted directly to livestock, thus feeding meat and do not feed us directly. There is colossal leeway here.