Evaluation of excess Lifetime Cancer risk from gamma dose rate in Quarry area of Shira, Bauchi State, Nigeria.

Abstract

Background: Terrestrial gamma radiation is the major source of outdoor radiation exposure to human beings.

Objectives: To obtain baseline data on environmental terrestrial radiation and to assess the corresponding cancer risk in the quarry area of Shira.

Method: 100 measurements of gamma dose rate were taken at 1m above the ground using two survey meters (Inspector Alert manufactured by S.E. International and Radiagem, 2000 Geiger Muller Counter) and the coordinates of each measurement point were recorded using a geographical positioning system (GPS).

Results: The gamma dose rate varied from 72.50 nGyh^-1 to 320.0 nGyh^-1 with a mean value of 148.32 nGyh^-1, which is about two times higher than the world average value of 59 nGyh^-1. The radiological health information which are the total annual effective dose equivalent and lifetime cancer risk is computed from the measured gamma dose rate. The total annual effective dose equivalent due to gamma dose is found to be 1.23 , which is below the worldwide average of 2.4 mSv/y. The excess lifetime cancer risk (ELCR) varies from  to   with a mean value of , which is higher than the worldwide average of  Sv/y. The calculated radiological hazard which is cancer risk is higher than the permissible limits set by (UNSCEAR, 2000).

Conclusion: Measured data could be used to evaluate public radiation exposure and in formulating safety standards and radiological guidelines.