Effects of per-household processes on the levels of chlorpyrifos residues in lettuce (Lactuca sativa)

Abstract

The study was organized to evaluate residue levels of chlorpyrifos on Lactuca sativa that are likely to have accumulated on crop during cultivation and also examine the effect some pre-household treatment procedure on residue levels on the crop grown in a tropical and humid environment. Chlorpyrifos residue was extracted using acetonitrile. Subsequent detection and a quantification were done using GC with PFPD. Concentrations of Chlorpyrifos applied at different stages of growth of lettuce were examined at different time intervals of 1 h, 24 h and 7 days after pesticide application. The results showed that residue levels detected at 1 h and 24 h after application were all above the MRL of 0.05 mgkg-1 and can pose health risk to consumers while that recorded 7 days after application were far below the MRL. Accumulation of chlorpyrifos on crop during cultivation was not observed since no significant differences were observed 7 days after application at all the different stages. There is therefore the need for farmers to allowed 7 days’ re-entry intervals before harvesting. The results also showed that, all the pre-household treatment procedures caused significant reduction in residues levels of chlorpyrifos on the crop. Mild detergent treatment was however more effective compared with the other treatments. Hence to reduce the risk associated with intake of chlorpyrifos through lettuce, mild detergent washing procedures should be followed before consumption.