A Systematic Review of Arsenic, Lead, and Manganese Occurrence through Drinking Water in East Africa

Toxic metals (TMs) harm human health, causing cancers, irreversible neurocognitive impairment, and cardiovascular disease. Drinking water is an important source of exposure to TMs. However, current peer-reviewed literature does not adequately capture or synthesize the extent of TM occurrence in drinking water in East Africa. The goal of this systematic review is to report and synthesize available evidence on the occurrence of TMs in drinking water across the region. A global systematic review of TMs in drinking water was recently conducted by Fisher et al., and data from East Africa were used for this analysis. A search of studies from PubMed, EBSCO Global Health, and Web of Science was conducted in 2019, with a search update in March 2025. We included studies published in English after 1968 that included a primary measurement of at least one TM of interest in drinking water in the region. In total, 111 studies (of the 3,993 reported in the larger systematic review) met these criteria. Among TMs of health concern, sufficient East African observations were available for Arsenic, Lead, and Manganese, making these the focus of this regional review. For each metal, average concentrations and the percentage of observations exceeding World Health Organization Guideline Values were calculated, with further analysis of observations by Urban and Rural and by Joint Monitoring Programme Improved and Unimproved categorization. 24%, 17%, and 31% of observations of Arsenic, Lead, and Manganese exceeded their respective WHO Guideline Values. Additionally, many urban centers and large portions of the region were geographically underrepresented in the literature. The synthesized data are sufficient to recommend primary prevention and progressive remediation efforts to prevent and minimize exposure to TMs in drinking water across East Africa. Nevertheless, substantive literature gaps remain, indicating a need for further research across much of the region.