The contamination of the environment by pesticides is very real, as is their negative impact on biodiversity and ecosystems, according to a report released Thursday by Inrae and Ifremer, two public research institutes specializing in agriculture and of the sea.
Two years and forty experts
Carried out at the request of three ministries (Ecological Transition, Agriculture, Research), this meta-analysis mobilized for two years around forty experts who reviewed some 4,000 scientific studies already published, in a French or comparable context, to summarize knowledge on the impact of plant protection products on biodiversity and ecosystems.
It intervenes in a context of reflection on the use of pesticides. Since the Grenelle Environment Forum at the end of 2007, which had set a target of reducing the use of synthetic pesticides by 50% in ten years, successive plans have failed. At EU level, a proposal is under consideration to halve the use of pesticides by 2030.
A last report in 2008
The last reports of this type dated from 2005 and 2008. Today “the image is much more precise of this contamination, due in particular to the densification of the surveillance networks, but also to the improvement of sampling techniques or analysis”, explains Wilfried Sanchez, Deputy Scientific Director of Ifremer.
The observation: contamination that affects all environments, concerns not only a variety of active substances but also transformation products, adjuvants and co-formulants, even if the latter are less sought after.
Agriculture in the crosshairs
The concentration is found mainly in agricultural areas, where the products are used, and spreads “along the land-sea continuum to reach the oceans, with a decrease in concentrations by a dilution effect”, describes Sanchez. Contamination can persist, even if it decreases over time, as shown by the sometimes persistent presence of products that are currently prohibited (eg DDT, lindane, diuron).
And if there are various factors affecting biodiversity (climate change, exploitation of resources, modification and destruction of natural habitats), “the available studies published over the last 20 years allow us to assert in a robust way that plant protection products are one of the causes major factors in the decline of certain populations”, emphasizes Stéphane Pesce, of INRAE.
Among the species affected, there are, for example, terrestrial invertebrates, including pollinating insects such as bees or beetles that prey on certain pests, as well as birds. Some of the synthetic products “contribute strongly to the risk” of extinction which weighs on 9 to 15% of the species listed in Europe, he insisted. Bats and amphibians are also affected.
The study also highlights the sub-lethal effects – which disrupt the functioning of organisms without causing rapid death – the subject of recent research: loss of orientation, immune deficiencies, but also behavioral changes. The indirect effects are also “better and better characterized”, notes Pesce.