Original Research Article
Year: 2020 | Month: December | Volume: 10 | Issue: 12 | Pages: 70-79
Determination of Excess Relative Risk of Radon from Residential Buildings in Some Selected Cities in Southwestern, Nigeria
Olukunle Olaonipekun Oladapo1, Olatunde Micheal Oni2, Emmanuel Abiodun Oni3, Adetola Olufunke Olive-Adelodun4, Abraham Adewale Aremu5
1Lecturer I, Department of Science Laboratory Technology, Ladoke Akintola University of Technology, P.M.B. 4000 Ogbomoso, Nigeria.
2Professor, Department of Pure and Applied Physics, Ladoke Akintola University of Technology, P.M.B. 4000 Ogbomoso, Nigeria.
3Lecturer II, Department of Physics with Electronics, Oduduwa University, Ipetumodu, Ile Ife, Nigeria.
4Lecturer II, Dept. of Physics, Hallmark University, Ijebu-Itele, Ogun State, Nigeria.
5Lecturer II, Department of Physics with Electronics, Dominion University, Ibadan.
Corresponding Author: Olukunle Olaonipekun Oladapo
ABSTRACT
Background and Purpose: One of the major causes of lung cancer has been traceable to the inhalation of radon (222Rn) emanating from indoor residential and workplace buildings. Extensive measurements of radon concentrations in homes have shown that although concentrations vary widely, radon is universally present, raising concerns that radon in homes has a finite possibility of increasing lung-cancer risk for the general population.
Method: A total of 210 residential buildings (30 per city) with commonest combination of covering materials for walls, ceilings and floors in some cities in South-western Nigeria were investigated using RAD7 radon detector. The commonest combination of covering materials were (A): paint, paint, carpet; (B): paint fiber board, plastic tiles; (C): paint, fiber board, ceramic tiles for walls, ceilings and floors respectively.
Result: The mean indoor radon concentration measured ranged from 54.03Bq m-3 to 65.01 Bq m-3 for all the combinations investigated from city to city and were found to be higher than the world average of 40 Bq m-3 but lower than the recommended action level of 200 Bq m-3 set by International Committee on Radiological Protection(ICRP). A test of significance carried out using analysis of variance (ANOVA) revealed that there is significance difference (p < 0.05) in the radon concentration from one location to another and among different combinations of covering materials. The estimated lung cancer risk which lie between 13 per million person per year (MPY) to 63 MPY for USEPA, ICRP and UNSCEAR risk models were very low and comparable with data from many countries of the world according to UNSCEAR (1993). The excess relative risks (ERR) increases cumulatively with age up to 54 years and declines discontinuously for ages 55 upward for both the duration and concentration models. At age 75 and above, there is no noticeable difference in the increase in death rate between the duration and concentration models adopted by BEIR VI for all the combinations of covering materials.
Conclusion: This result showed vividly that the risk of developing lung cancer from radon exposure in residential buildings investigated increases with radon concentration and exposure duration with no known threshold concentration below which radon exposure presents no risk.
Key words: lung cancer risk, indoor radon, covering materials, buildings, excess relative risk, radon concentration.