Assessment of groundwater quality, irrigation suitability, and health risks from radon and heavy metals near Ilokun dumpsite, Ado-Ekiti, Nigeria

Concentrations of 222Rn and other toxic metals (Ni, Cu, Fe, Cd, Zn, Pb, Cr, and Mn) have been measured by alpha spectrometry using Rad7 and atomic absorption spectrophotometry, respectively, in the water samples taken around the Ilokun dumpsite, Ado-Ekiti, Nigeria. The physicochemical parameters of the groundwater were also assayed to determine its suitability for drinking and irrigation purposes. While the physicochemical parameters met the World Health Organization (WHO)-safety standards, Cu, Fe, Cd, Pb, Cr, and Mn exceeded the respective threshold limits. The hazard index (HI) values for adults (8.40) and children (39.23) indicated heightened susceptibility to non-carcinogenic health risks among both age group populations. The levels of Rn-222 contents present in the studied samples range from 5.4 to 23.1 Bq l(-1) with an average of 13.9 Bq l(-1). Approximately 60% of the samples have radon concentrations above the US Environmental Protection Agency (EPA)-maximum contaminant level of 11.1 Bq l(-1). The evaluated radiation doses to the stomach and respiratory tract due to radon content in the water are well below the WHO-specified individual dose criterion of 0.1 mSv year-1. The result of this study suggests a need for groundwater resource management strategies and measures to protect human health from radiological and toxicological risks associated with groundwater consumption around the Ilokun dumpsite.