Abstract:
In this research, the annual effective dose rate (AEDR) due to ionizing radiation in 20 Local
Government Areas (LGA) and 37 Local Council Development Areas (LCDA) in Lagos State,
Nigeria have been determined. Data acquisition was carried out with the use of a Geiger-Muller
counter. A global positioning system (GPS) device was used to take readings of the coordinates
and elevation of each data point. The isolevels of the AEDR in the study area was represented by
using the kriging interpolation technique on ArcGIS 10.1 software. Duncan multiple range test was
performed using Statistical Package for Social Sciences (SPSS) software so as to determine if there
is any significant difference between the distributions of the annual effective doses in the study
area. The result obtained shows that the values of the AEDR ranged from 0.19±0.01 mSv/y to
0.35±0.02 mSv/y with a mean value of 0.27±0.03 mSv/y. This value is lower than the maximum
permissible limit of 1 mSv/y as recommended by ICRP. Comparing the geospatial map of the
AEDR and that of the elevation map in the obtained result, the AEDR was higher in areas with
high elevations and lower in areas with low elevations. The distribution of the AEDR to different
organs (gonad, breast, red bone marrow, lung, thyroid, bone e.t.c) of the body, the excess lifetime
cancer risk (ELCR), the collective effective dose equivalent (SE) and the collective health detriment
(G) were calculated so as to assess the effects of ionizing radiation on the populace of the study
area. The ELCR range from 0.0007 to 0.0012, with an average value of 0.0010. The average value
of the excess lifetime cancer is close to the recommended permissible limit of 1 as recommended
by ICRP. Hence, the populace of the study area are now so much at risk of developing cancer over
a period of time. The total collective effective dose equivalent is 4839.49 person-Sv. This implies
that approximately twenty-eight (28) in every one hundred thousand (100,000) people are at risk
of suffering radiation-induced disease in the State.
