Assessment of heavy metal contamination in fish, fruits, and vegetables in Southwest Nigeria: A systematic review

Abstract

<ns4:p> Background The aim of this systematic review was to investigate the prevalence of heavy metal contamination in fish, fruits, and vegetables in Southwest Nigeria. The review focused on studies published over a ten-year period, between 2014 and 2024. Methods Articles used for the study were obtained by conducting a comprehensive literature search using several databases, including ResearchGate, Scopus, Google Scholar, ScienceDirect, and PubMed using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). To identify relevant studies, a plethora of keywords were utilized to search for articles in the selected databases, including. Articles reporting heavy metal contamination in specified food products within the last decade were included. Results Of the 10,212 initially identified articles, 64 met the inclusion criteria after thorough screening. The selected studies were predominantly conducted in Lagos (30), Ondo (8), and Ogun (7) states, with few studies in Oyo, Ekiti, and Osun states. The majority of the research focused on fish (40 studies), followed by vegetables (20) and fruits (4). The commonly studied fish species were observed to be <ns4:italic>Tilapia zilli</ns4:italic> , <ns4:italic>Chrysichthys nigrodigitatus</ns4:italic> , <ns4:italic>Clarias gariepinus</ns4:italic> , and <ns4:italic>Oreochromis niloticus</ns4:italic> , with heavy metal concentrations frequently exceeded WHO limits. Conclusions Therefore, this review highlights the significant risks posed by the presence of heavy metals in food products and underscores the importance of stringent environmental monitoring and the adoption of appropriate regulatory mechanisms for health and environmental risk mitigation. This could help in the formulation of appropriate policy implementation strategies geared towards mitigating heavy metal contamination in the region’s food supply. </ns4:p>