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pesticides destroy biodiversity

Are pesticides dangerous for living organisms? ? At the request of the government, forty-six researchers worked on the question for two years ; they compiled, compared and analyzed more than 4,000 studies. The answer, made public Thursday, May 5, is in three letters: yes, they pollute all environments and weaken biodiversity. This observation is not new, but it is now supported by solid scientific expertise.

This is an inventory of existing knowledge », specifies Sophie Leenhardt, researcher at the National Research Institute for Agriculture, Food and the Environment (Inrae), who carried out the work with the French Research Institute for the Exploitation of the Sea (Ifremer ). The last collective expertise of this magnitude dates back to 2005. The objective, according to Mme Leenhardt: Inform the debate and public action, without giving an opinion or formulating recommendations. » At a time when the French State is wondering how to allocate the millions of euros of the common agricultural policy, this document nevertheless provides damning elements against intensive agriculture.

Widespread contamination of ecosystems

The report highlights widespread contamination of ecosystems » by pesticides, especially in agricultural areas. Each year, between 55,000 and 70,000 tonnes of active phytopharmaceutical substances are sold in France… a large part of which therefore ends up in the environment. This pollution affects all media — soil, air, water — and involves a variety of substancessays Wilfried Sanchez, Deputy Scientific Director of Ifremer. We find the active substances of pesticides, but also their transformation products and their adjuvants. »

For example, glyphosate, one of the best-selling herbicides, is used with additives to enhance its effectiveness. ; and when the product degrades, a new, equally toxic molecule is created, Ampa. Plant protection products are found even in the seas, along the coasts, but also in the seabednotes Mr. Sanchez. We even found DDT [un insecticide interdit en France depuis 1972] hundreds of kilometers away, in areas close to the poles. » Small consolation, the prohibited products see their concentration decreasing little by little.

Involuntary glyphosate pissers displaying the concentration of the herbicide present in their urine, in 2018. © Julie Lallouët-Geffroy/Reporterre

However, the degree of contamination remains difficult to quantify. The diversity of the substances analyzed remains limited with regard to those which are potentially present — 294 active substances and more than 1,500 commercial preparations are currently authorized in Franceinsists the report. Many substances are not researched, especially among the most recently placed on the market. » The only certainty: this widespread pollution interferes in many living organisms – even in human urine.

Amphibians and dolphins would fall ill more easily

Unsurprisingly, this impregnation weakens all living things. First threatened, those who live not far from the fields: bees, bumblebees, ladybugs, butterflies, birds… Available studies confirm that plant protection products are one of the major causes of population decline. » insects, birds, aquatic invertebrates…, summarizes Stéphane Pesce, researcher in ecotoxicology at Inrae. On a European scale, it is estimated that contamination would induce losses of up to 40 % within macro-invertebrates [larves ou mollusques] aquatic. »

These chemicals don’t just kill living beings. They have many sub-lethal effectspoints out Mr. Pesce, that is to say, they disturb the organism », without being fatal. Loss of orientation, immune deficiency, modification of reproduction… More and more unexpected effects with no clear relationship to the known mode of action are highlighted, for example with regard to the nervous, immune, endocrine systems, or even interactions with microbiota. », notes the report. Amphibians and dolphins would fall ill more easily.

Hedge planting and wetland restoration

The researchers also highlight a butterfly effect: by suppressing insects or destroying part of the vegetation, insecticides and herbicides reduce the food resources and habitats of many animals, including certain birds. Pesticides act as an aggravating factor in the state of health of ecosystems, ranked fourth among the factors weighing on nature on a global scale », recalls the report. In 2019, theIPBESthe Biodiversity IPCC », warned of the possible disappearance of a million species, due, among other things, to chemical pollution. Pesticides would also be the first engine » the decline of insects, specified a parliamentary study published last January.

What to do ? The collective expert appraisal does not extend to the subject, other work being in progress. She nevertheless cites a few action levers. The first lever for reducing contamination is reducing the quantities of plant protection products used », reads the report. Alas, the policies implemented so far have proved ineffective in getting rid of pesticides. Researchers list promising avenues, such as planting hedges and restoring wetlands to create buffer spaces » capable of absorbing and degrading some of the substances.

On the regulatory side, the two research institutes point to significant progress to be made. Because, although European regulations in this area are one of the most stringent in the worldexplains Laure Mamy, researcher at Inrae, it has limits ». The authorities responsible for authorizing (or not) products do not sufficiently analyze the cocktail effects — the consequences of combined exposure to several substances — nor the chain effects of a product on an entire ecosystem. Need a more systemic approach »insists Grandma. As European authorities prepare to reauthorize glyphosate, this scientific report should sound like a warning.

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