Assessment of Heavy Metals and Microbial Pollution of Lettuce (Lactuca sativa) Cultivated in Two Sites (Paspanga and Tanghin) of Ouagadougou, Burkina Faso

Environmental pollution can have detrimental effects on crop yield and its consumers. The current study was designed to investigate the potential human health risks associated with the consumption of lettuce crop contaminated with toxic heavy metals and microbiological status. Irrigated water, soil and lettuce were analyzed by AAS technics for heavy metals including Cd, Cr, Cu, Mn, Ni, Pb and Zn. Transfer factor (TF), daily intake of metals (DIM) and health risk index (HRI) were also calculated. Microbial analysis was carried out for the presence foodborne pathogens. The results showed that the heavy metals contents were higher in the soil than wastewater and the vegetables. Heavy metals ranged (mg·Kg-1) for Cd (1.27 to 2.93), Cr (7.28 to 7.38), Cu (0.91 to 1.70), Mn (0.29 to 6.60), Ni (1.74 to 2.16), Pb (1.32 to 1.69), Zn (3.08 to 3.79); and were higher than the WHO maximum limit permissible (ML) in vegetables. HRI < 1 indicates minimal risk. TF values designated an enhanced bio-contamination. Microbial numeration revealed the presence of spoiler and pathogenic microorganisms. The lettuce tested was not safe for human use, especially for direct consumption by human beings.