Pesticide Residues in French Soils: Occurrence, Risks, and Persistence

Contamination ofthe environment by pesticide residuesis a growingconcern given their widespread presence in the environment and theireffects on ecosystems. Only a few studies have addressed the occurrenceof pesticides in soils, and their results highlighted the need forfurther research on the persistence and risks induced by those substances.We monitored 111 pesticide residues (48 fungicides, 36 herbicides,25 insecticides and/or acaricides, and two safeners) in 47 soils sampledacross France under various land uses (arable lands, vineyards, orchards,forests, grasslands, and brownfields). Pesticides were found in 98%of the sites (46 of the 47 sampled), including untreated areas suchas organic fields, forests, grasslands, and brownfields, with up to33 different substances detected in one sample, mostly fungicidesand herbicides. The concentrations of herbicides were the highestin soils with glyphosate, and its transformation product, AMPA, contributed70% of the cumulative herbicides. Risk assessment underlined a moderateto high risk for earthworms in arable soils mostly attributed to insecticidesand/or acaricides. Finally, the comparison with pesticide applicationby farmers underlines the presence of some residues long after theirsupposed 90% degradation and at concentrations higher than predictedenvironmental concentrations, leading to questions their real persistencein soils. Only a few studies have investigatedpesticides in soils.This work highlights the widespread occurrence of multiple pesticidesin soils putting earthworms at risks. Several residues were more persistentthan expected, and new critical pesticides were identified.

Automated summary

The contamination of the environment by pesticide residues is a growing concern. This study monitored pesticide residues in 47 soil samples across France and found that pesticides were present in 98% of the sites, including untreated areas. The persistence of some residues and their potential risks to earthworms were highlighted.