The content of pesticide residues in fruit and vegetables is influenced by washing, peeling and cooking. Processing factors, reflecting the change in concentration of these residues following processing, help to refine the risk assessment for consumers. Four commodities (carrot, celery, spinach and melon) were selected in combination with a panel of pesticides (acetamiprid, azoxystrobin, boscalid, carbendazim, chlorpyrifos, lambda-cyhalothrin, cyromazine, deltamethrin, difenoconazole, dimethoate, imazalil, iprodione, linuron, mancozeb, maneb, phenmedipham, pirimicarb, propamocarb, tebuconazole, thiamethoxam), on the basis of most frequently consumed matrices and of the high frequency of detection for these pesticides. For some combinations pesticide-commodity-processing, significant reductions in residue levels were observed up to 90% during washing and peeling, 70% during blanching and 99% during sterilization. However, other combinations did not lead to any reduction, or occasionally lead to the production of more toxic compounds. Indeed, during the sterilization of spinach, maneb degradation has led to the emergence of ethylenethiourea. The variability, which was sometimes very strong for processing factors determined for the same combination, leads us to question the current regulations, which are currently based on the evaluation of only two processing factors. Although the physico-chemical properties of pesticides may explain the processing factors obtained for leaves vegetables like spinach, our work illustrates that a broad range of parameters actually influence the processing factors, as for example the application time of pesticide or the choice of variety. These elements support the relevance of a reassessment of agricultural practices in order to limit further risks for the consumer.