Assessment of food safety and dietary exposure to rice from rotations with different agricultural intensification

Abstract

Rice (Oryza sativa L.) is a global staple, so pesticide residues in grain are a critical food safety issue amid agricultural intensification. Nine paddy-rice samples from a seven-year Uruguayan long-term experiment with six rotations of contrasting intensification and pesticide history were analysed using validated QuEChERS multi-residue methods coupled to LC-MS/MS and GC. Of 41 pesticides and metabolites, 40 were below detection limits (typically 0.005–0.01 mg kg−1). Thiamethoxam was quantified in two samples (0.011–0.012 mg kg−1) and attributed to spray drift from adjacent non-rice crops, not to rice intensification or seed treatment. A conservative deterministic assessment for the most exposed group equalled 0.38% of the acceptable daily intake. Intensification did not impair grain safety after seven years: residues were essentially absent, dietary exposure was far below toxicological thresholds, and the residue profile met more than 95% of US and EU standards.