Contamination of air by pesticides

There is a need to define a national monitoring scheme for pesticides in air

Air pollution caused by pesticides, one of the components of atmospheric pollution, remains less well documented than pesticide contamination of other media (water, food, etc.). For example, there is currently no national surveillance plan or regulatory value for pesticide contamination of outdoor and indoor air.

Concerning the air inside homes or public buildings, a few initiatives, mainly as part of the Indoor Air Quality Observatory (OQAI), have revealed the presence of some substances in this environment.

For outdoor air, since the early 2000s, the approved air quality monitoring associations (AASQAs) have been carrying out regional measurements of pesticides. They have collected more than 450,000 items of data, which are available in the PhytAtmo database. As partners in the phytopharmacovigilance (PPV) scheme, they have also been forwarding all these data to ANSES since 2015.

Establishing national surveillance of pesticide residues in air is therefore a priority defined in the framework of the Government's action plan on plant protection products and the 2017-2021 national plan for the reduction of atmospheric pollutant emissions (PREPA). This second plan sets objectives for characterising the presence of pesticides in air.

In an expert report published in 2017, ANSES made recommendations on how to implement and conduct an exploratory campaign to establish permanent national monitoring of pesticides in air.

The CNEP: an essential prerequisite for defining a national surveillance scheme

This national exploratory campaign to measure pesticides in outdoor air (CNEP) was conducted jointly by ANSES, Ineris and the AASQA network. Over a 12-month period and according to a harmonised protocol for the very first time, 75 substances were measured at 50 sites representing both rural and urban areas. In one year, more than 112,000 items of data were collected and 1,300 samples were analysed for each substance. The scope and duration of the project were unprecedented, both at national and European level.

The CNEP therefore provided a snapshot of the substances found in outdoor air, along with their concentration levels. In addition to the data collected by the AASQAs, this inventory could be added to the data collected as part of specific studies to assess the exposure of populations living near emission zones in particular (PestiRiv, for example, which was launched jointly by ANSES and Santé Publique France at the end of 2019 and whose results are expected in late 2023).

Among the 75 targeted substances, data were collected for 12 substances not listed in the PhytAtmo database, including glyphosate, fluopyram and pentachlorophenol. Of the 75 substances screened for, 70 were detected at least once during the campaign. Five substances (carbetamide, chlordecone, dieldrin, oryzalin and tebuthiuron) were never detected.

The 57 substances quantified during the CNEP included some, such as lindane, which are nevertheless prohibited. A greater number of substances were quantified in metropolitan France (56 substances) than in the French overseas territories (19 substances), reflecting the differences in the various uses between these territories. The substances frequently quantified were broadly similar in metropolitan France and the overseas territories, and corresponded to the following nine substances: chlorothalonil, chlorpyriphos-methyl, folpel, glyphosate, lindane, pendimethalin, prosulfocarb, S-metolachlor and triallate.

In metropolitan France, eight substances – chlorothalonil, chlorpyriphos-methyl, fenpropidine, folpel, pendimethalin, prosulfocarb, pyrimethanil and triallate – had annual average concentrations above 0.1 nanograms per cubic metre of air. Of all the substances measured in metropolitan France, folpel and prosulfocarb stand out from the others due to their significantly higher concentration levels and an annual average of around 1 and 2.6 nanograms per cubic metre of air, respectively.

Temporal variations in concentrations were also observed. These are consistent with known treatment periods and different agricultural profiles (arable crops, viticulture, arboriculture). On the other hand, the measurement campaign did not reveal any significant differences in the concentration levels of substances from one type of residential area to another ("rural", "suburban" and "urban").

On the basis of the CNEP results, ANSES carried out initial interpretation work to assess the health impacts of 70 substances confirmed in outdoor air. This analysis identified 32 substances requiring further investigation, which will ultimately contribute to the definition of a national surveillance scheme for pesticides in air.