Sanitary Quality of Lettuce (Lactuca sativa L.) and Mint (Mentha spicata L.) Grown at the Dogona Market Garden in Burkina Faso

Abstract

Background: Consumption of vegetables irrigated with wastewater from the Houet backwater exposes the population to significant health risks. Using wastewater for irrigation, producers use chemical and organic fertilisers and pesticides to increase agricultural yields and control pests. However, these agricultural practices can harm the health and properties of soil, water resources and crops. Aim: This study was conducted to assess the sanitary quality of vegetables produced at the Dogona site.  Methodology: A total of 24 samples of lettuce (Lactuca sativa L.) and mint (Mentha spicata L.) were taken at random from the Dogona market garden site. Four sampling sites (P1, P2, P3, P4) were selected along the irrigated perimeter. The heavy metal concentrations in the plants sampled were analysed by atomic absorption spectrometry on the dried vegetables. XLSTAT 2016.02.27444 software was used for variance analysis. Results: The results obtained showed a significant accumulation of heavy metals. Indeed, mint accumulated more heavy metals than lettuce. The average concentrations in mg/kg DM of Cr, Fe and Pb in mint were 3.96, 1896 and 0.64, respectively. Meanwhile, the concentrations found in lettuce were 3.25 for Cr, 1522.38 for Fe and 4.04 for Pb. These values greatly exceeded the thresholds recommended by the Codex Alimentarius, set at 2.3 mg/kg for chromium, 425.5 mg/kg for iron and 0.3 mg/kg for lead. Conclusion: The presence of heavy metals in lettuce and mint grown at the Dogona site compromises the safety of these foods. The results obtained from this study reveal that the levels of heavy metals present in lettuce and mint grown on the SMD far exceed the regulatory thresholds for human consumption. In view of the results obtained, there is therefore a need to take appropriate measures to secure the food chain. These findings suggest the need for better irrigation and monitoring practices.