Pesticide residues in fruits and vegetables: exposure and health risks among consumers from farm-to-fork in Kampala Metropolitan Area in Uganda

Abstract

Background: Dietary exposure to pesticides is associated with adverse health effects. This study determined pesticide residue concentrations, potential human health risks and consumers percep\tions towards risk in fruits and vegetables from farm-to-fork in Kampala Metropolitan Area (KMA) in Uganda. Methods: Pesticides were measured in 160 fruit and vegetable samples and analysed using liquid chromatography – tandem mass spectrometry and gas chromatography – mass spectrometry. Fruits and vegetables consumption information was collected from 2,177 consumers. Pesticide concentrations were compared with European Union maximum residual limits (EU MRLs). Mean values of pesticide concentrations; and fruits and vegetables intake and body weight were used to calculate the estimated daily intake (EDI) of pesticide residues. EDI values were compared with acceptable daily intakes (ADI) to calculate the hazard quotient (HQ) by age group, and stage of consumption along the chain. A hazard index above 1(HQ > 1) indicated that exposure to pesticides has the potential to induce health risks among the consumers. Semi-structured questionnaires (50), in-indepth interviews (16) focus group discussions (8) were used to collect data on post harvest processing and consumers’ perceptions on potential health risks due to exposure to pesticide residues. Qualitative data was coded deductively and inductively, with recurring ideas organized into categories to form sub-themes and consequently overarching themes. Results: The major pesticides classes found in the produce (% detection frequency) were organophosphates (91.3%), carbamates (67.5%), pyrethroids (60.0%) dithiocarbamates (48.1%), and neonicotinoids (42.5%). Twenty-seven pesticides either decreased or increased along the chain, with dioxacarb decreasing and methidathion and quinalphos increasing with statistically significant trends. Washing, wiping, peeling and cooking were the post-harvest processing methods that explain the increasing trend for methidathion and quinalphos and descreasing for dioxacarb. Concentrations of fonofos, fenitrothion and fenhexamid were above the European Union MRLs. Hazard quotients based on dietary ingestion scenarios for eighteen pesticides exceed 1, including dichlorvos (444) alanycarb (314), fonofos (68), fenitrothion (62), dioxacarb (55) and benfuracarb (24), indicating possibility of chronic health risk, that decreased with age. Consumers were aware of the potential health risks due to dietary exposure to pesticides, and relied on washing, peeling, drying and cooking or a combination to reduce the risk. Conclusion: Fruits and vegetables on the KMA markets were found to be contaminated with pesticide residues that have potential to cause chronic health risks from ingestion especially among children. There is urgent need to reduce consumer exposure to pesticide residue in fruits and vegetables.