Cumulative Dietary Risk of Pesticide Mixtures in Plant-Based Foods: Beyond Single-Compound Regulatory Compliance

Abstract

Dietary exposure to pesticide mixtures is recognized as an important food safety challenge worldwide, particularly in countries with intensive agricultural production. Regulatory monitoring programs focus primarily on compliance with maximum residue limits (MRLs), whereas cumulative exposure to pesticide mixtures remains insufficiently addressed. This study investigated the occurrence of eleven currently used pesticides in 20 commonly consumed plant-based foods (60 samples) marketed in Brazil and assessed regulatory compliance and human health risks associated with dietary exposure. Residues were determined by gas chromatography–mass spectrometry, and concentrations were compared with Brazilian MRLs and crop authorization status. Risk characterization included the hazard quotient (HQ), the hazard index (HI), and the carcinogenic risk (CRisk), estimated using cumulative assessment groups based on shared toxicological targets. Multiple residues were detected across all commodities, with chlorpyrifos, pirimiphos, imidacloprid, malathion, and fipronil most frequently associated with non-compliant samples. Several residues corresponded to pesticides not authorized for the respective crops, suggesting misuse, environmental contamination, or compliance failures; imidacloprid exceeded its MRL in zucchini by more than 70-fold. The carcinogenic risk from atrazine remained below accepted thresholds. In contrast, cumulative non-carcinogenic risk identified cassava, strawberry, and spinach as the commodities of greatest concern, with an HI of 3.16 for cassava. Fipronil residues drove these results, accounting for 83–99% of the cumulative hazard. These findings indicate that regulatory compliance alone may not capture the health risks of pesticide mixtures. Strengthened monitoring, improved traceability, and cumulative risk approaches are needed to protect consumer health and support evidence-based regulation.