French rivers are polluted by detergents, insecticides, herbicides and drugs, with possible impacts on natural environments and human health, according to two joint studies by the National Institute for the Industrial Environment and Risks (Ineris ) and the French Biodiversity Office (OFB).
As part of their monitoring work on French freshwater, Ineris and the OFB evaluated the concentrations of 141 organic contaminants at 1,600 points in French rivers recorded in water and sediments between 2016 and 2018. 122 of these contaminants , "The great majority, did not show any exceedance of eco-toxicological thresholds, or exceptionally on a limited number of sites (less than 5% of sites)", according to a joint press release.
However, “for the 19 remaining contaminants, chronic impacts or sub-lethal effects on aquatic populations cannot be excluded”.
"These contaminants are essentially detergent residues (up to 95% of sites with thresholds exceeded), insecticides (up to 40%), herbicides (up to 25%) or drugs (up to 20%)", specifies the press release.
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The presence of selenium in the sediments seems "very critical", and that of metolachlor - a pesticide used in the cultivation of corn -, of carbamazepine - an anticonvulsant drug - and of diclofenac - anti-inflammatory drug - in the waters "moderately critical. », In metropolitan France as well as in the overseas departments and regions. These so-called micropollutants "are known or suspected for their harmful effects on human health or on ecosystems at very low concentrations," according to the press release. But, contrary to a stubborn misconception, it is therefore not antibiotics or contraceptive hormones that bathe our rivers.
"On a few highly contaminated sites, the concentrations of certain compounds (detergent or biocidal residues) can exceed 10 or even 100 times the chronic impact threshold values, suggesting possible acute impacts on local biodiversity", point out warns Ineris (National Institute for the Industrial Environment and Risks) and the OFB.
These substances can come from domestic uses, industry, agriculture or transport and can be found in nature through the discharges of wastewater treatment plants or the leaching of agricultural or urban soils by rainfall.
