Monitoring and dietary risk assessment of 81 pesticide residues in 11 local agricultural products from the 3 largest cities of Cameroon

This study monitored 81 pesticides residues in 160 samples of 11 dry agricultural products collected in the 3 largest cities of Cameroon, extracted using QuEChERS method and analysed by liquid chromatography tandem mass spectrometry (LC-MS/MS). Residues of 58 (71.6%) compounds were found in the samples, the most distributed pesticides were Imazalil, Triadimenol and Pyrimethanil, and those with the highest average concentrations were Cymoxanil, Thiamethoxam and Thifensulfuron. Half of the positive pesticides were above their European Union maximum residue limits (MRLs) among which Carbaryl, Carbofuran, Malathion, Metalaxyl and Propoxur are pesticides banned in the country. All the 11 food items contained pesticides, the highest contamination rates (12.8%-5.0%) were found in white pepper, maize, Egusi seeds and groundnuts, while groundnuts, Egusi seeds, maize and soybeans showed the highest residue concentrations (1.46-1.37 mg/kg). Pesticide contamination rates were similar in the 3 sampling cities, but Bafoussam and Yaounde had more samples above the MRLs than Douala. Using the food consumption data for Cameroon from the recent SubSaharan Africa Total Diet Study, dietary exposure was calculated and potential health risk of Cameroonian consumers was evaluated. Hazard quotient of Carbofuran in groundnuts was 22% above the safe value, the remaining food items could be considered safe for individual pesticide residues, although Triazophos and Metribuzin in maize were of concern. Groundnuts (0.531) and maize (0.443) showed high hazard index, with 17 highly contributing compounds, but there is no reason to be concerned about cumulative exposure to residues from the food items. While the food items are in general safe to eat, to minimize the increasing human health risk of consumers and ensure approval of Cameroon export produces on international market, this study suggests that authorities must regulate the usage of agrochemicals, strengthen the controls for effective implementation of the pesticide bans and implement strong control of obsolete pesticide stocks in the country.