Two and a half decades of radioactivity studies in Tanzania: A systematic review of progress and perspectives (2000–2025)

Radioactivity studies provide critical data for assessing natural radiation exposure to humans and the environment. In Tanzania, numerous investigations have been conducted to quantify natural radionuclides in building materials, soils, rocks, food and water in order to establish baseline levels and ensure radiological safety. This study presents a systematic review of 33 research articles on environmental radioactivity in Tanzania and their associated environmental implications. Relevant studies published in English between 2000 and September 2025 were identified through targeted searches of major databases, including Scopus, Web of Science, Google Scholar, ScienceDirect, PubMed and ResearchGate. The results indicate that activity concentrations of natural radionuclides vary widely among different environmental matrices, reflecting the combined influence of geological formations and human activities. Overall, the reviewed data suggest that natural radioactivity levels in Tanzania are generally comparable to global averages; however, several studies report clearly elevated activity concentrations and radiological hazard indices in specific regions and samples, particularly in rocks and soils from mining areas, indicating the presence of localized high-radiological-risk zones rather than uniform national comparability. Methodologically, all reviewed studies employed high-purity germanium (HPGe) detectors for gamma spectrometric analysis, ensuring high accuracy and reliability for gamma-emitting radionuclides; however, this approach limits the detection of alpha-emitting radionuclides such as 210 Po and 210 Pb. The lack of complementary techniques, including alpha spectrometry and liquid scintillation counting, therefore constrains a comprehensive assessment of radiological risk, highlighting the need for future studies incorporating advanced analytical methods and broader geographic coverage to achieve a more complete understanding of environmental radioactivity in Tanzania.