Annual effective dose from 222Rn in groundwater of a Nigeria University campus area

Abstract

Radon, the heaviest among the noble gases in the periodic table of element is a radioactive nuclide that is naturally available in rocks, soil and water. It has become the subject of many research efforts in recent years due to its leading role in causing cancer. In this study, a total of 68 groundwater samples were collected and assayed using alpha spectrometry with RAD7 radon detector with RAD-H2O accessories manufactured by Durridge CO (USA). The 222Rn concentration measured were in the range of 0.6–36.2 Bq L−1 with an average of 13.33 Bq L−1, 7.0–41.5 Bq L−1 with mean value 23.3 Bq L−1 and 0.6–27.4 Bq L−1 with an average value of 7.4 Bq L−1 for hand dug wells (HDW), hand pumped boreholes (HPB) and motorized boreholes (MBH), respectively. About 54, 86 and 15% of samples from the HDW, HPB and MBH, respectively, exceeded the parametric reference level of 11.1 Bq L−1 suggested by United State of America Environmental Protection Agency but lower than the permissible limit of 100 Bq L−1 by World Health Organization (WHO) and European Union. The average annual effective doses resulting from inhalation and ingestion of radon in water obtained for the three groundwater sources are less than recommended limits by WHO and ICRP. The data obtained from this study are comparable with similar studies conducted in Nigeria and other parts of the world as reported in literature. Continuous radon monitoring in drinking water and indoor environment is however recommended for the study area.

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

“…Each water sample was automatically analyzed by the detector in four cycles of 5 min each, with an initial aeration time of 5 min. This was necessary for quality control purposes and to guarantee reliability of analytical methods [11,18]. Since the counting was not immediately done at the sample collection point, radon concentration in the samples must have reduced due to radioactive decay.…”

“…Direct ingestion results in radiation dose delivery to the human stomach while inhalation pathway delivers dose to the lungs and respiratory track. Annual committed effective dose (ACED) to human stomach from direct ingestion of radon-contaminated water in the studied community was calculated from the equation [11,35]:…”

“…Levels of 222 Rn in water should therefore be measured, checked and controlled consistently in order to protect the human population from internal exposure that may arise from inhalation and ingestion of waterborne radon Isinkaye et al [11],underscores the importance of water to human existence and an expressive indices for radiological, geological and environmental studies. Hence, its purity, accessibility and quality cannot be jeopardized especially from the point of view of human health and protection.…”

Measurement of radon concentration in water within Ojo axis of Lagos State, Nigeria

“…European Commission and the World Health Organization has proposed concentration of 222 Rn in the drinking water, 100 Bq/l as the standard limit [25]. In general, groundwater resources rather than surface water have much higher concentration of radioactive materials such as 222 Rn [21,[27][28][29][30][31][32]. Many of these studies have concluded that there are strong correlations between the concentration of radon and the geology of surrounding environment.…”

“…Consumption of water which contains enhanced activity concentrations of 222 Rn could elevate the effective dose received by man and raise the cancer risk [32].…”