General context:

Plant Protection Products (PPPs) help to keep crops healthy and prevent damage or destruction by disease and infestation. A PPP contains at least one active substance that can be either organic or inorganic, natural or synthetic. Phytopharmaceutical treatment with a PPP may leave residues of the active substance in the form of the parent compound and/or metabolites (breakdown products) in food and/or feed commodities, with possible consumer and/or livestock exposure via ingestion. Consumer exposure to pesticide residues may be of concern depending on the toxicity of the residue compounds, the amount of residue found in food commodities, and the diet of the considered population (Kim, Kabir, & Jahan, 2017). Characterising pesticide residues from a qualitative and quantitative point of view is key to both risk assessment in the framework of pesticide approval and risk management. The number of available publications is a clear illustration of increasing concern around consumer exposure to pesticide residues in food: a rapid search in the Scopus database using the terms “pesticide” AND “residue” AND “food” in titles yielded around 10 000 documents since 1951, with a considerable increase in recent decades. Publications have increased by a factor of seven since the year 2000.

In the European Union (EU), these concerns are addressed during the evaluation or re-evaluation of both active substances at the European level and PPPs at the zonal level (administrative zones) prior to marketing authorisation or re-authorisation. To this end, the residue section of the evaluation focuses on the residue definition in food, the amount of residues to be expected in food, and lastly on consumer exposure. In the framework of this project, we will focus on one specific item of this residue section, namely the effect of process (industrial or domestic transformation of the raw commodities) on the nature of the residue in food. Currently, if use of a PPP leads to significant residue levels in a raw agricultural commodity (RAC), a study investigating the degradation pathway of the residue during the process, called a hydrolysis study, is required. These types of studies are carried out on buffer solutions fortified with radiolabelled active substance that undergo different hydrolysis processes (OCDE, 2007c). The use of radiolabelling studies makes it possible to monitor every potential breakdown product that may form during the process. A limited number of hydrolysis conditions defined by three parameters (temperature, pH and time) are set to be “representative of the most widely used industrial and domestic food processing technologies”. These hydrolysis conditions, however, do not cover processes at temperatures higher than 120 °C, such as cooking with a conventional oven or in a pan, frying or using a microwave oven. Since further degradation is expected with increasing temperatures, one can assume that certain metabolites may form above 120 °C. As an example, the active substance pyraclostrobin breaks down into several transformation products during deodorisation of olive oil (240 °C), while pyraclostrobin parent compound remains stable at temperatures ranging from 90 to 120 °C (Germany, 2018).


The purpose of the CRD PhytoCuisson is:

(1)  to review academic research literature (referred to as public literature) as well as literature submitted by pesticide manufacturers in the framework of pesticide evaluation. Comparing the two sets of literature aims at discussing the need for future studies to investigate the pesticide degradation pathway during high temperature processes (>120 °C) in the regulatory framework of pesticide evaluation as well as conducting hydrolysis studies with high-temperature hydrolysis conditions (>120 °C). We have published the review in Food Chemistry: review

(2) to prioritize pesticides that may be susceptible to degradation at temperatures above 120°C - an article on this prioritization list will be released soon

(3) to build a methodolgy based on HRMS and thermogravimetric approaches in order to discover unreferenced by-products - an article is in preparation

(4) conduct the research in order to detect and characterize pesticides by-products by using the prioritization list and the methodology built previously - new results will come soon



ANSES Laboratory of food safety, ANSES Direction of regulated products, University of Creteil, CNRS and INERIS