Annual effective dose estimation due to gross alpha and beta activities in groundwater samples from breweries in Nigeria

Abstract

Background: Water makes up about 90 to 95 percent composition of beer products. The presence of natural radionuclides in groundwater samples used in Nigeria breweries' which spontaneously decay with the emission of gross alpha and beta activities (Gα and β RAC) when ingested, may result in internal irradiation of the human body. It is therefore imperative to determine the potential radiation hazard (Annual effective dose). Materials and Methods: Groundwater samples were obtained from fourteen (14) different brewery sites in Nigeria. Fifteen (15) ml/L of 1 mol/dm3 of concentrated Trioxonitrate (v) acid was added into each groundwater sample immediately after collection from the sources to preserve the radionuclides from container wall adsorption. Further sample preparation and analysis were carried out in the laboratory of Ghana Atomic Energy Commission, Accra using Method 900 of the US Environmental Protection Agency. Canberra iMaticTM Automatic low background gas-filled counter was used for determination of Gα and β RAC in groundwater samples. IBM SPSS version 20 was used for statistical analysis. Annual Effective Dose (AED) in groundwater samples were estimated using a mathematical formula: AEDα/β (mSv y-1) = Aα/β x IRw/b x CF.Results: Mean values for Gα and β RAC in Nigeria breweries' groundwater samples were 0.370±0.34 Bq/L and 0.193±0.26 Bq/L respectively. Values for Gα RAC were higher than the WHO recommended safe limits for most brewery sites whereas the Gβ RAC were within the safe limit established by WHO. Highest AED value due to alpha emitting radionuclides in groundwater samples was recorded in Northern Nigeria (1.3240 mSv/y) while south-south region recorded the least value (0.6209mSv/y) but were all above the WHO recommended safeguard of 0.1mSv/y. Conclusion: Results obtained from this study were above the recommended WHO safe level and therefore may pose radiological health hazards to consumers. Radioactivity water treatment plant as well as routine radiation monitoring are recommended for all breweries' groundwater sources in Nigeria.