Health Risk Assessment of Heavy Metals via Consumption of Lettuce (Lactuca Sativa L.) Collected From Selected Open - Markets and Supermarkets In The Accra Metropolis

Abstract

Background: Bioaccumulation of metals in vegetables is known to harm human health. Food contamination by heavy metals has been a major public health concern since the consumption of such foods can cause deleterious effects. The study aimed to measure and compare levels of heavy metals in lettuce sold in selected supermarkets and open markets in Accra Metropolis and their implication on human health. Objectives: The specific objectives of the study were to measure and compare concentrations of heavy metals in lettuce from markets and supermarkets in Accra Metropolis, compare concentrations of heavy metals with FAO/WHO standards and assess the potential human health risks associated with consuming lettuce with the measured heavy metal concentrations. Methods: This was an analytical cross-sectional study conducted in Accra Metropolis. A total of 16 samples of lettuce (approximately 15kg) from two varieties (Eden and Great lakes) were selected for heavy metals analysis where two samples of each of the two varieties were randomly selected across four markets namely the (Palace Mall and Melcom Plus) and two ‘open markets’ (Madina and Kaneshie Markets). All analyses namely; mean, standard deviation, and ANOVA were conducted using IBM Statistical Package for Service Solutions (version 26.0). Results: The study indicates that there were relatively higher levels of metals in open-market lettuce samples than in supermarkets. Studies showed higher levels of copper and zinc in lettuce leaves as compared to Cadmium and Lead. Again, the study showed Iron, zinc, and manganese having concentrations exceeding the threshold (0.70 - Fe, 0.30 -Zn, 0.14 -Mn). Conclusion: Out of the 16-lettuce sampled from the open – markets and the supermarkets the findings revealed that Risk level analysis associated with the use of Lettuce by humans indicates that the concentrations of Pb, Cu, and Cd found in them were below permissible limits, however, Mn, Zn, and Fe were found to have levels of concentration which were above the permissible limit and poses a potential health risk to consumers using various reference guides/standards. Even though almost all the heavy metal levels detected in this study were far below the WHO permissible limits, the essential metals detected had a relatively higher concentration. Therefore, vegetables sampled from the selected supermarkets and open markets in Accra are not hazardously contaminated by heavy metals and are largely safe for consumption.