Annual E_ective Dose and Excess Lifetime Cancer Risk due to Ingestion and Inhalation of Radon in Groundwater of Bosso Community Minna, North-Central Nigeria

Abstract

Radon in potable water has become an issue of public health concern, especially when consumed or used directly from source for domestic purposes without any pre-treatment. In this study, 222Rn concentration in 22 water samples collected from 2 groundwater sources (open wells, 12 samples and boreholes, 10 samples) in Bosso town, North central Nigeria were measured using Durridge RAD-7 radon detector with RAD-H2O accessories. 222Rn concentrations in open wells varied from 2.1_0.7 to 27.9_2.5 Bq L􀀀1 with a mean of 10.2_1.5 Bq L􀀀1, while that in boreholes ranged from 2.8_1.1 to 39.2_1.5 Bq L􀀀1 with a mean value of 14.3_1.7 Bq L􀀀1. These values are lower than the 100 Bq L􀀀1 upper limit proposed by the European Union Commission, above which any practical intervention may be necessary. Mean annual committed e_ective dose to adults, children and infants from ingestion of water were 74.64, 71.58 and 53.17 _Sv y􀀀1 respectively for the open wells and 104.24, 99.96 and 74.26 _Sv y􀀀1 respectively for borehole water samples. Mean whole body dose due to ingestion and inhalation of waterborne radon from open wells and boreholes are 27.56 and 38.48 _Sv y􀀀1 respectively, which are below the reference level of 0.1 mSv y􀀀1 for potable water recommended by the World Health Organization for public safety. The excess lifetime cancer risk were 0.10 _ 10􀀀3 for the open wells and 0.13 _ 10􀀀3 for the boreholes, which are lower than the world safety limit 0.29 _ 10􀀀3. Water from the two groundwater sources investigated is therefore fit for consumption and other domestic usage from the point of view of radiation protection.