Nearly two-thirds of non-organic fruits and half of non-organic vegetables contained traces of pesticides between 2017 and 2021. Last February, the association Generations Futures published this state of play of fruits and vegetables sold in France. Until now, it was thought that washing fruits and vegetables could be enough to protect against ingesting these substances. But a new study from Anhui Agricultural University (China) attests to the presence of pesticides beyond the skin of apples, in the flesh.
Thanks to the development of a very precise imaging technique, Dongdong Ye's team managed to identify traces of pesticides in the outermost layer of pulp of the fruit. Their results were published in the journal Nano letters.
Maximum limits for pesticide residues
“ There are thresholds, maximum residue limits (MRLs), defined by a strict regulatory framework", recalls Roger Genet, former director general of Anses, during a interview on pesticides in 2018.
Beyond these thresholds, the marketing of products for humans and animals is prohibited. Limits are established after an assessment of chronic hazards and risks, with a significant margin of safety, " he adds. In its 2024 report, Future Generations warned of the exceeding of these limits.
In first place was passion fruit. Over 5 years, more than 37% of samples of this fruit analyzed exceeded the tolerance thresholds. In fifth place in this ranking of bad students: The apple. It is this fruit that scientists from the Chinese Agricultural University have examined closely.
Read alsoPesticides: “eternal pollutants” increasingly present in fruits and vegetables in Europe
Washing your fruit is not enough
To analyze the apple samples, Dongdong Ye's team relied on an increasingly popular technique: DRES (Surface Enhanced Raman Scattering). It is widely used in the detection of trace substances in the field of food safety because it is simple, rapid, and very sensitive, » summarizes the first author of the study, during an interview for Science and Future.
This method consists of revealing chemical signatures using light. To make them even more visible, the molecules to be analyzed are stuck to a metal surface. The patterns thus created serve as molecular signatures and can be used to identify small quantities of specific compounds, " specify the authors.
But this technique has several flaws, which the researchers have tried to eliminate. Indeed, rigid metal surfaces do not adapt well to the irregularities of the samples. The authors therefore used a flexible substance, cellulose, which they immersed in a silver nitrate solution. This process resulted in an extremely precise technique.
For their tests, the researchers sprayed two known pesticides on the surface of the apples: thiram and carbendazim. Alone, or together. Later, they rinsed them, " in order to imitate everyday practices"But by applying their method of analysis, the researchers realized that the pesticides were still present, at low concentrations. Even more surprising, they were not confined to the skin of the apples, and reached the pulp.
Analysis of the samples revealed traces of pesticides in the flesh of the fruit, less than half a millimetre from the skin. These results suggest that washing alone may not be sufficient to prevent pesticide ingestion and that peeling may be necessary to remove the contaminated skin and thin layer, " conclude the authors.
How to reduce your exposure to chemical risk?
Today, agricultural production is regularly Controlled. Roger Genet, former director of Anses, recalled in 2018: “ The presence of traces of contaminants does not necessarily mean a health risk.“
He added: " For consumers, it should be noted that the main risk is often associated with particular behaviors, such as high consumption of a given food or group of foods."Diversifying your diet therefore helps reduce your exposure to chemical risk.
Concerning children, the National Nutrition Health Program (PNNS) recommends not starting the food diversification only from 6 months. Diversification can lead to exposure to certain contaminants which may be greater than that resulting from the consumption of infant formula, without this being considered a cause for concern,Roger Genet.
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