Malathion residues on selected fresh vegetables produced by small scale farmers of Chinsali district,Muchinga province,Zambia

Abstract

Vegetables are a vital source of fiber and vitamins which also support disease prevention. To increase the efficiency of vegetable production; Farmers use chemical pesticides so that losses of vegetable growth to pests are minimized. However, these pesticides are poisons that can adversely affect human health if residue quantities are beyond permissible limits. Therefore, a study was conducted with the aim of assessing the presence of Malathion residues on selected fresh vegetables sold in markets of Chinsali district. A cross sectional study involving forty (40) small scale farmers from three Agriculture camps of Chinsali district were randomly selected and a structured questionnaire was administered. Forty vegetable samples were collected from the same farmers of which 19 were rape and 21 were tomato samples that were taken to laboratory with the aim of determining the presence and quantity of Malathion pesticide residues. Chemically analysis was conducted on collected vegetable samples using gas chromatograph with selective Electron Capture Detector (ECD). A total of 40 vegetable samples were collected and sent for analysis at Zambia bureau of standards in Lusaka. The 40 samples consisted of 21 tomato and 19 rape samples. Analysis showed that 31 (78%) of the 40 samples had Malathion. Residue contamination ranging from 0.65mg/kg to 19.34mg/kg. Twenty one (21) fresh tomato samples analyzed, 19 (90%) were found to be contaminated with malathion of which 9 (43%) were heavily contaminated above recommended maximum residue limit value of 8mg/kg according to the Food and Drugs Act Chapter 303 of the Laws of Zambia. Out of the 19 vegetable samples of rape, 12 (63%) were found to be contaminated with malathion residues of which 3 (16%) were heavily contaminated above recommended threshold limit value of 8mg/kg Food and Drugs Act Chapter 303 of the Laws of Zambia. Studies showed that gender, level of education, location of the farm (Agriculture camp), farm size, source of pesticides, farmers source of information, pesticide information source, vegetable type, able to read label instructions were not significantly associated with malathion residue contamination of tomatoes and rape, (p value > 0.05). However, age of a farmer was significantly associated with Malathion contamination of tomatoes and rape. Farmers between the age 41 and 50 years old were 1.5 more likely to produce Malathion residue contaminated vegetables (P 0.0001, CI 1.67-3.332) while farmers above 51 years of age were 40% less likely to produce malathion contaminated vegetables than younger farmers (P 0.001, CI -1.37, -0.43). The study also showed that farmers who had poor knowledge of pesticide environmental effects were 60% less likely to have their vegetables contaminated with pesticides. Vegetables produced in Chinsali by small scale farmers had Malathion pesticide residues above maximum residue limits. The main factors associated to pesticide residue concentration on fresh vegetables include age and inadequate knowledge on environmental effects of pesticides. Keywords: Malathion, Maximum Residue Limit (MRL), pesticide residues