Chlorothalonil is a substance found in agrochemicals used by farmers to control mold, mildew, bacteria and algae. The substance was banned from use in Switzerland at the beginning of 2020 and across the EU by the end of May 2019.
Chlorothalonil is toxic to fish and aquatic invertebrates and can cause kidney and stomach damage in humans and renal tumors in rodents and dogs, according to the World Health Organisation (WHO). In vitro tests done in the 1990s show the substance has the potential to damage DNA. In addition, the use of the chemical has also been linked to declining bee populations.
According to the newspaper SonntagsZeitung, Eawag researchers found 6 nanograms of the substance per litre of Evian water, a level within the 100 nanogram legal limit.
Evian mineral water comes from the Cachat spring not far from Lake Geneva and is considered to be so pure that some water researchers use it to calibrate their measuring devices. However, while checking their devices using the water, the Eawag team discovered it contained chlorothalonil.
They also tested their instruments with other waters. Water from the Limmat river (7 nanograms) and the Rhine (53 nanograms) both contained more chlorothalonil than Evian water. However, water from Lake Zurich (5 nanograms) contained less than the famous bottled water.
Philippe Aeschlimann, a spokesperson for Evian, said the pesticide concentration measured by Eawag researchers is below the usual detection limit and is not relevant for consumption. However, Franziska Herren of the drinking water initiative thinks even low concentrations add to the overall pesticide exposure that comes with all the food and drink we consume every day, something she described as a constant poisoning of our bodies.
Juliane Hollender, coauthor of the Eawag study, said she was surprised that chlorothalonil residues were found at a water source so far from intensive farming. How they got there remains unclear.