Lifetime cancer risks of radon and heavy metals levels in groundwater wells around limestone quarry in Ogun State, Nigeria

Background: Radon ( 222 Rn) and carcinogenic metals are major contaminants in groundwater wells.This research aimed on evaluating the possible lifetime cancer linked with the presence of radon and carcinogenic metals in groundwater wells situated close to a limestone quarry in Ewekoro, Ogun State, Nigeria.Materials and Methods: Twenty (20) groundwater wells near a limestone quarry were sampled for water sample collection.Radon levels in water were assessed utilizing CR-39 detectors, whereas concentrations of carcinogenic metals were analyzed via atomic absorption spectrometry.The resultant data facilitated the estimation of potential lifetime cancer risks for adults exposed to water from these wells.Results: The measured radon concentrations varied between 2.161.7 and 11.881.6Bql -1 , with an average of 6.67 2.15 Bql -1 across the 20 samples.A significant portion, 81%, of the samples exhibited radon concentrations below the permissible limit of 11.1 Bql -1 fixed by the United States Environmental Protection Agency (USEPA).The annual effective dose (AED) attributable to inhaled and ingested radon ranged from 5.444.3 to 29.944.0Svy -1 and 15.7713.9 to 86.7211.7 Svy -1 , respectively.The collective AED across all water sample sources varied from 21.2116.7 to 116.6715.7 Svy -1 , with average values of 65.43410.4Svy -1 .The cumulative incremental lifetime cancer risk related to the ingested carcinogenic metals adults ranged from 9.70 10 -5 to 1.0310 -4 with a mean value of 9.72 10 -5 .Conclusion: Water wells situated closer to the limestone quarry exhibited higher mean radon concentrations, while those farther away from the quarry maintained mean radon concentrations below the acceptable limits provided by the World Health Organization (WHO) and the USEPA.