Abstract:
Thc indoor-outdoor radiation dosc Icvels, and radioactivity Icvels of natural radionuelidcs in soil
and watcr samplcs of 56 locations of Bangladcsh wcrc measurcd. Thc radiation dosc Icvcls at thc scabcachcs
of Bangladcsh and thc conccntrations of naturally occurring radionuelidcs in thc sand samplcs of
Cox's Bazar sea-beach' ~nd Kuakata sea-beach were also measurcd. Thc radiation dose Icvels wcre
measured' by a calibrated portable radiation dose ratc survcy-meter PDR I Sv. The assessment of
radioactivity levels in soil, sand, and water sa.mples were pcrformcd by a high-rcsolution low background
HPGe dctcctor. Radiatioil dose due to radioactivity insoi! samples and intake of water samples werc also
assesscd.
111eavcrage indoor dose levels at kntcha-houses, new-buildings, and old-buildings werc found to
be 0.23 :t 0.04 IlSv.hr", 0.25. :t 0:04 IlSv.hr", and 0.27 :t 0.04 IlSv.hr" respectively. The weightcd .
average indoor dose levels in all kinds of houses was found to be 0.24 :t 0.04 ,.Sv.hr'l. Thc average
outdoor dose level was fonnd to be 0.20 :t 0.07 IlSv.hr". The ratio of average indoor dose level to
avcrage outdoor dose level was found to be 1.2. The total average effective dose cquivalcnt due to
external natural radiation was estimated to be :...2 mSv.y". The average conceJitrations of 2J2Th, mU,
40K, and 137CSin soil samples were found to be 83.56:t '17.96 Bq.kg", 44.35 :t 12.65 Bq.kg'l, 630.89:t
173.85 Bq.kg",. and 5.37 :t 4.87 Bq.kg,l respectively. TIle average activities of the mentioned
radionuelides in water sanlplcs were found to be 249.59:t 51.67 mBq.L,I, 156.77:t 30.46 mBq.L'I, 9.08
. :t 3.36 Bq.L,I, and 1.17 :t 1.80 Bq.L,1 respectively. TIlc average al\llual effcctivc dose equivalcnt duc to
ingestion of water was fonnd to be 74.01 :t 21.41 IlSv ranging between 24.20 :t 5.57 IlSvand 134.04 :t
16.10 flSV. The average allllual effective dose equivalent due to terrestrial radiation was found to bc J .26
:t 0.27 mSv with a range from 0.56 :t 0.08 to 1.88 :t 0.09 mSv. TIle average dose levcl in the shiningbrown
colonred smidy area.s in Cox's Bazar sea-beach was found to be 8.94 :t 3.15 mSvfl ranging
betwecn 6.39 :t 2.28 mSvf' and 11.91 :t 4.29 mSvf' whilc !he average dose level in shining-brown
'coloured sandy areas of Kuakata sea-beach was found to be 4.20 :t 0.88 mSvfl ranging from 2.98 :t
0.70 mSv.y,1 to 5.87:t 0.18 mSvf'. The average radiation dose levels in public areas of Cox's Bazar
sea-beach, Potenga sea-beach, and Kuakata sea-bcach were fonnd to be 1.49 :t 0.18 mSvfl, 1.58 :t 0.2'6
mSvf', and 1.58 :t 0.35 mSvf' respectively.
By plotting the cumulativc frcqucncy plots for thc avcrage conccntrations of radionuelides and
average radiation dose levels, the geometric mean and geomctric standard deviation for each type of data
were estimated and compared with the corresponding aritlnnetic mean and standard deviation. Exccpt the
137Csconcentration in water samples, all data were found tt? be distribnted nonnally. A good correlation
between the corresponding concentrations of radionuelides in soil and water smnples of the smnc placc
was found ..
Thc average fatalcancer.risk was found'to be 101 per 106 people with a range from 78 to 144
. cases per million peoplc, based on thc measured average dose levcl.