Study on the effect of grain storage and processing on chlorpyrifos-methyl and pirimiphos-methyl residues in post-harvest treated wheat with regard to baby food safety requirements

Anna Balinova (1) , Rosica Mladenova (2) , Doncho Obretenchev (2)

1 Toxicology
2 Toxicology

A study was undertaken to assess the effects of storage intervals and of milling procedures on dissipation of chlorpyrifos-methyl and pirimiphos-methyl residues in post-harvest treated wheat grain with the aim to obtain scientific data on compliance of the processed products with the safety requirements concerning baby foods. The insecticide formulations were applied on stored wheat at recommended rates (20 ml.t-1). The initial concentration levels in whole grain were determined in samples taken 1 h after treatment. The dissipation of residues and their distribution in different fractions of the milled grain were studied after various storage intervals, from 7 to 270 days after treatment. Samples of treated grain were milled in fractionating laboratory mill and 8 fractions - bran, semolina, 3 types of groats and 3 types of flour were collected and analyzed for determination of pesticide residues. The residues were determined by an analytical method based on acetone extraction, graphitized carbon clean-up and GC-ECD, respectively GC-NPD determination of residues. The limits of determination of both pesticides were 0.005 mg.kg-1 - high enough for enforcement of the European Commission (EC) Directive that established a maximum residue level (MRL) of 0.01 mg.kg-1 for any pesticide in cereal-based baby food. The results showed that the pesticides chlorpyrifos-methyl and pirimiphos-methyl applied post-harvest on wheat as grain protectants were distinguished by relatively low rates of degradation in the grain under practical storage conditions. Milling did not reduce significantly the bulk of the chemicals but resulted in distribution of residues in various processed products. The main part of the insecticides deposited on the grain remained in the bran and partly in semolina fractions. 270 days after treatment the residues of chlorpyrifos-methyl were within the range of 0.8 – 2.1 mg.kg-1 and of pirimiphos-methyl - between 0.6 and 3.7 mg.kg-1 in the various types of flour. Keywords: chlorpyrifos-methyl, pirimiphos-methyl, post-harvest treatment, wheat grain, processing products, residues, baby food

Mots clés: Life Sciences

Anna Balinova, Rosica Mladenova, Doncho Obretenchev. Study on the effect of grain storage and processing on chlorpyrifos-methyl and pirimiphos-methyl residues in post-harvest treated wheat with regard to baby food safety requirements. Food Additives and Contaminants, 2006, 23 (04), pp.391-397. ⟨10.1080/02652030500438035⟩. ⟨hal-00577572⟩