Radiological and related chemical health impact assessments of uranium in pipe borne water from some waterworks in Lagos metropolis, Nigeria

Abstract

The common purifying technique of water for public (human) consumption in Nigeria is by chlorination which only eliminates the microbial contaminants, but the radioactive contaminants remain unaffected. There had been no serious radiological and related chemical health impact assessments of pipe borne water in the country. Water samples were collected from five waterworks across Lagos Metropolis and a single crystal NaI (Tl) detector was used to determine the activity concentration of 238U radionuclide in the water. The radiological health impact assessment determined includes annual effective dose rates and risk of incurring cancer. Using activity concentrations obtained and the relation from United State Environmental Protection Agency (USEPA), the chemical health impact such as life average daily dose (LADD) and hazard quotient (HQ) due to ingestion of ²³⁸U in water were determined and data were analyzed using descriptive statistics. The mean ²³⁸U activity concentrations were 15.3±4.1 Bql^-1, 14.6±5.2 Bql^-1, 9.7±2.0 Bql^-1, 11.0±2.9 Bql^-1 and 11.3±1.8 Bql^-1 for Agege, Shomolu, Iju, Saka and Amuwo respectively. The least mean effective dose, 0.3±0.1 mSvy^-1 was obtained in Iju while the highest, 0.5±0.2 mSvy^-1 was obtained in Agege and Shomolu. The least mass concentration of 174.2±35.7μgl^-1 was obtained in Iju and the highest of 274.9±73.3 μgl^-1 was obtained in Agege. The highest mean cancer mortality and morbidity risks, (0.6±0.2) x10^-3 and (0.9±0.2) x10^-3 respectively were obtained in Agege. The activity concentrations of radionuclide in the water were low hence the morbidity and mortality risks in the study were low when compared to the world average value of 1.0x10^-3. The result showed high radioactivity and chemical levels therefore caution and control should be taken to avoid any health crisis later in future.

Keywords: uranium impact assessment, pipe born water, water works, Lagos metropolis, Nigeria