Evaluation of radiological hazard Indices and Excess Lifetime Cancer Risk in Ishiagu Quarry Site, Ebonyi State, Nigeria

Abstract

A radiometric survey of background ionizing radiation (BIR), estimate the excess
lifetime cancer risk and its radiological hazard indices in Ishiagu quarry site in
Ebonyi State were carried out, using a nuclear radiation monitor (Radalert 200)
and a geographical positioning system (GPS) for location coordinate. The
measured average exposure rates and its equivalent dose rate ranged from
0.0138mRh−1 (1.1605mSvy−1) to 0.0172mRh−1 (1.4465mSvy−1) with mean value of
0.0156mRh−1 (1.3087mSvy−1). The calculated mean outdoor absorbed dose rate
for each area ranged from 119.71 nGyh−1in the Pit Area 1 to 155.21nGyh−1in the
Crush Area 2, with a mean value of 135.44nGyh−1. The estimated mean annual
effective dose equivalent (AEDE) rate for each area ranged from 0.1835 mSvy−1
to 0.2379 mSvy−1, with a mean value of 0.2076 mSvy−1, while the mean excess
lifetime cancer risk (ELCR) for each area ranged from 0.6056 to 0.7852, with a
mean value of 0.6852. The mean BIR values obtained and all the calculated
radiological hazard indices were all higher than the world average permissible
limit as stipulated by the International Commission on radiological Protection in
the entire Quarry site. The calculated dose to organs/tissues of the quarry
workers and residents ranged from the lowest organ dose of 0.076404mSvy−1
(10%) liver to the highest organ dose of 0.136199mSvy−1 (18%) testes. However,
these values indicates that the Ishiagu Quarry site may not be radiologically
healthy for both workers and individuals living in the area as possible chance of
contracting cancer of both workers and residents is insignificant.