Assessment of age-dependent inhalation doses and population attributable risk from radon exposure in water samples from the industrial area of Igbesa, Ogun State, Nigeria

Abstract Indoor air radon due to radon in potable water results in inhalation radiation exposure. In this study, age-grouped annual effective inhalation doses for infants (15 years), and population attributable risk (PAR) for lung cancer are calculated based on the radon activity in 20 water samples of Igbesa, Nigeria. Radon activity ranged from 5.7 ± 1.3 to 39.7 ± 8.3 Bq/L (mean 13.5 ± 2.5 Bq/L). Indoor air contributions from radon (C R ) with a transfer factor of 0.1 Bq/m 3 air per Bq/L water were 0.6 ± 0.1–4.0 ± 0.8 Bq/m 3 (mean 1.4 ± 0.3 Bq/m 3 ). Doses, computed on the basis of an equilibrium factor of 0.4, occupancy of 0.6, and 8760 h/y, ranged between 0.022 ± 0.005–0.150 ± 0.031 mSv y−¹ for infants and 0.010 ± 0.002–0.068 ± 0.014 mSv y−¹ for adults. Child dose is approximately 1.33 times, and infant dose 2.1 times the adult dose, due to different dose conversion factors. However, at these ambient levels, age-dependent variations are minimal and not a primary concern. PAR ranged from 0.0009 ± 0.0002 to 0.0063 ± 0.0013 (0.09%–0.63%). These low risks, lower than International commission on radiological protection guidelines, show negligible effect, but industrial effects require continued monitoring. PAR values are retained as a benchmark, indicating negligible contribution to lung cancer burden at ambient levels.