Radiological Risk Estimates Due to Background Exposures in Selected Hospitals in South – East Nigeria

Abstract

Radiation is present everywhere on the Earth and humans are exposed to it without being aware of it. Exposure to natural ionizing radiation is inevitable as long as we live on Earth. An in-situ measurement of indoor and outdoor exposure dose rates of Federal Medical Center Umuahia (FMC Umuahia) and Federal Medical Center Owerri (FMC Owerri) were measured with well calibrated radiation meters (Radalert-100 and Digilert-200). The average indoor and outdoor exposure rates for Federal Medical Center Umuahia were 0.014±0.003 and 0.014±0.003 mRh-1, while that for Federal Medical Center Owerri were 0.012±0.002 mRh-1and 0.013±0.002 mRh-1. The values show that the exposure rates for Federal Medical Center Owerri is within the range of the World threshold value of 0.013 mRh-1, while that of FMC Umuahia is higher. The average indoor and outdoor absorbed dose rate  measured at federal medical centre (FMC) Owerri are 106.7 and 104.7 nGyh-1 respectively while the average indoor and outdoor absorbed dose for Federal medical center (FMC) Umuahia  are 120.1 and 116.8 nGyh-1 respectively. These values exceeded the world average of 89 nGyh-1. Also the results for average excess lifetime cancer risk (ELCR) calculated for indoor and outdoor for the hospitals show that ELCR for both indoor and outdoor exposures were all higher than the world acceptable value of 0.29x10-3, but the annual effective dose levels for the hospitals both indoor and outdoor were all below the 1 mSvy-1 maximum permissible limit for the public set by the International Commission on Radiological Protection (ICRP). Therefore there is need for the management of the hospitals to monitor radiation levels in other to take necessary precautions to avoid radiation levels getting to unacceptable levels.