Levels of Chlorine and phosphorus containing pesticide residues on selected vegetables in Zambia

Tomatoes and cabbage samples were analysed for chlorpyrifos and monocrotophos residues by Gas Chromatography (^GC) vntYv electron capture detector. One field o? tomatoes and cabbage was treated for four weeks at the recommended dose of 0.61/Ha monocrotophos and 21/Ha chlorpyrifos. A second field treated twice in seven days with chlorpyrifos and monocrotophos. A
th ird field was not treated at all. The analysis revealed that tomatoes sprayed twice only showed tolerable levels of chlorpyrifos residues while the monocrotophos residues exceeded these
levels. No residues were detected after the twenty first day. The residues detected in the cabbage
that was sprayed twice only rose to a maximum on the twenty first day after the initial spraying and then decreased to levels above the FAO/WHO Maximum Residue Limits (MRL's). Both tomatoe and cabbage sprayed weekly retained residues with cabbage showing higher levels than
tomatoe. The residues detected in the cabbage, sprayed weekly, were as high as 18.268mg/kg for
chlorpyrifos and 29.043mg/kg for monocrotophos i.e. well above the recommended FAO/WHO
MRL's. Twenty percent of the tomatoe and cabbage samples obtained from the markets were found to have residues exceeding the recommended MRL's. This study also showed that despite the same treatment, tomatoe and cabbage responded differently to chlorpyrifos and monocrotophos and as
a result retained their residues in unequal quantities.