Diazinon residues levels in farm-gate Brassica oleracea var. Acephala of Kimira-Oluch Smallholder Farm Improvement Project, Kenya

Abstract

Pesticides use in vegetable production often has residual effects on the plants and environment with potential health risks. Diazinon, though associated with human health impacts, is a popular pesticide in the production of Brassica oleracea var. acephala at the Kimira-Oluch Smallholder Farmers Improvement Project (KOSFIP), Kenya. The long pre-harvest interval (PHI) of diazinon application may not be observed by farmers with inadequate appreciation of Good Agricultural Practices (GAP). It is not documented whether diazinon residues levels in the farm-gate Brassica oleracea var. acephala of KOSFIP could be a health risk to the consumers. The diazinon residues levels and corresponding health risks in farm-gate Brassica oleracea var, acephala at KOSFIP were determined. Cross-sectional survey based on snowball sampling identified 40 farms applying diazinon on the vegetable. Triplicate samples were collected from each farm for residue analysis, using the QuEChERS method, and LC-ESI-MS/MS analysis. Standard normal distribution function f(z), revealed 78% of farm-gate samples had detectable residual diazinon levels and 70% were above the Codex MRL of 0.05 mg/kg. The farm-gate Brassica oleracea var. acephala are exposing consumers to health risks. Efforts must be intensified to ensure GAP are adopted. The estimated farm-gate samples with health risk indices for children and adults (HRIc and HRIA) >1.0 were 64% and 26%, respectively. Farm-gate Brassica oleracea var. acephala diazinon levels are therefore causing high health risks to both children and adults. Farm-gate residual levels and HRI were comparatively higher than findings of most previous studies. Inappropriate label PHI and malpractices against GAP may be responsible for high residual levels. There should be regular surveillance and trainings of farmers on GAP for sustainable production of Brassica oleracea var. acephala in the Lake Victoria region. Use of diazinon on Brassica oleracea var. acephala should be discouraged and alternative approaches including integrated pest management practices should be encouraged.