EVALUATION OF EXCESSIVE LIFETIME CANCER RISK DUE TO BACKGROUND IONIZING RADIATION LEVEL OF BLOCK-MOLDING INDUSTRIES IN OSOGBO, SOUTHWEST NIGERIA

Abstract

Studies on radiation levels and radionuclide distribution in the environment provide important
radiological baseline information. This type of information is necessary in understanding human
exposure from natural and man-made sources of radiation. The natural terrestrial gamma radiation
dose rate is an important contribution to the average dose rate received by the world's
population.This study aimed to measure outdoor effective dose from gamma dose rates and to find
out that workers and people around block industries are not exposed to unwanted and high ionizing
radiation. In this study conducted in Osogbo, Osun State, the terrestrial gamma radiation dose rates
were measured in 10 molding locations. Measurements were made with digilert200 a portable survey
meter. The meter displays its reading in milliroentgen/hour (mR/h) which was later converted to
absorbed dose rate in nGy/h and annual effective dose in mSv/h. The study discovered that the
measured gamma dose rate with a mean of 190.00nGy/h ranged from 165.3nGy/h to 252.3nG/y. The
calculated annual effective dose ranged from 0.253mSv/y to 0.389mSv/y with a mean of 0.29mSv/y,
relatively. Higher dose rates were recorded in three of the industries located under the high-tension
transmission.

Keywords: Cancer risk, Absorbed Dose, Ionizing radiation, Gamma, Environment