Occurrence of Pesticide Residues and Dietary Exposure Assessment in Vegetables from Senegal’s Niayes Horticultural Zone

Abstract

Small-scale horticulture plays a major role in food security in Senegal, particularly in ensuring the supply of vegetables to local populations. The Niayes area represents one of the country’s main horticultural production zones owing to its favourable agroclimatic conditions. However, inadequate pesticide management and poor compliance with good agricultural practices may compromise the sanitary quality of horticultural products and increase consumer exposure to chemical hazards. This study aimed to assess farmers’ agricultural practices, determine pesticide residue levels in vegetables, and evaluate associated dietary risks. A field survey was conducted among 331 vegetable producers using the Wyckhuys and O’Neil approach. At the same time, 90 composite vegetable samples were tested for residues of 20 active pesticide ingredients using gas chromatography coupled with mass spectrometry (GC-MS). Of these substances, 19 were detected in at least one sample. Dietary risk assessment was performed using national vegetable consumption data to estimate contribution to pesticide exposure. The results showed that profenofos (87%) was the most frequently used pesticide, followed by emamectin benzoate (77%), lambda-cyhalothrin (73%), acetamiprid (72%), cypermethrin (51%), dimethoate (48%), and deltamethrin (47%), mainly applied during the pre-rainy season. Caterpillars were identified as the most prevalent pest (80% of citations), while pesticide management practices remained largely inconsistent with recommended agricultural standards. Cabbage was the most cultivated crop, followed by onion, potato, tomato and bitter eggplant. Residues exceeding Maximum Residue Limits (MRLs) were detected in 100% of okra samples, 93% of cabbage, 80% of turnip, 66% of bitter eggplant, and 62% of onion samples, whereas lower exceedance rates were observed for pepper (8%), potato (8%), and tomato (26%). The highest dietary risk was associated with lindane in carrot, onion and bitter eggplant, followed by dimethoate in cabbage, onion, carrot and okra. Overall, carrot and onion were identified as the vegetables posing the greatest potential health risk to consumers.