RISK ASSESSMENT OF EXCESS LIFETIME CANCER RISK (ELCR) IN FEDERAL MEDICAL CENTER, OWERRI, IMO STATE, NIGERIA

Abstract

Excess Lifetime Cancer Risks, Activity Concentrations, Radium equivalent activity (Ra_eq), absorbed gamma dose rate (D_r), annual effective dose equivalent (AEDE), external hazard index (H_ex), and annual gonadal dose equivalent (AGDE), were measured and evaluated from primordial radionuclides (²²⁶Ra, ²³²Th and ⁴⁰K) in 10 Soil samples collected from Federal Medical Center (FMC), Owerri, Imo State, Nigeria. Radioactivity measurements were carried out by the method of gamma-ray spectroscopy with a Thallium-doped Sodium Iodide [NaI (Tl)] detector. The mean activity values obtained for the radionuclides ²²⁶Ra, ²³²Th, and ⁴⁰K  in Federal Medical Centre (FMC), Owerri are: 20.56 ± 4.73, 14.96 ± 3.42, and 105.65 ± 31.40 Bqkg^-1, respectively.  These values were below the worldwide average values: 32 Bqkg^-1 for ²²⁶Ra, 45 Bqkg^-1 for ²³²Th, and 412 Bqkg^{- 1} for ⁴⁰K as documented by UNSCEAR. ⁴⁰K recorded the highest mean activity compared to ²²⁶Ra and ²³²Th in the studied soil samples, as shown in the table below. The mean computed values of the Excess Lifetime Cancer Risk are 0.08 x 10^-3 ± 0.03. The mean values of these hazard parameters were within the acceptable safe limits provided for human safety and environmental protection. This simply means that the Excess Lifetime Cancer Risk is insignificant or minimal from the studied samples.