Background: Presently, the British-American
Tobacco Company (BAT) located in Ibadan, Oyo State
is the only tobacco producing company in Nigeria
accounting for about nine different brands of cigarette
tobacco smoked in the country. The tobacco
leaves are produced from some farmlands located in
Oke-Ogun area of Ibadan where special fertilizers are
used for the growing of the tobacco leaves. The use
of this fertilizer may enhance natural radionuclide
contents in the farm soils and through root uptake be
accumulated in the leaves. In this study, soil samples
from three farmlands used for the production of the
tobacco leaves were collected in order to determine
the activity concentrations of 226Ra, 232Th and 40K in
the farm soil. Materials and Methods: Measurements
for the determination of the activity concentrations
were carried out using gamma-ray spectrometry
comprising a lead-shielded 76 mm × 76 mm NaI(Tl)
detector crystal (Model 802 series, Bicron NaI)
coupled to a Canberra series 10 plus multichannel
analyzer (MCA) (model 1104) through an preamplifier
base. Results: Results of measurements showed that
the average activity concentrations of the natural
radionuclides in the soil samples across the three
farms varied from 2550.4± 154.6 to 3208.9 ± 188.7
Bq kg-1 for 40K, 33.1±11.9 to 39.9±9.3 Bq kg-1 for
226Ra, while for 232Th it varied between 51.98± 8.4
and 56.08±17.51 Bq kg-1. The activity concentrations
of these radionuclides and gamma absorbed dose
rates due to the concentration of these radionuclides
were found to be higher than world average values
while those of the control farm values were lower to
world averages and the tobacco leaf farms.
Conclusion: From the results obtained the fertilizer
type used on the farmlands for the tobacco leaf
production was very rich in 40K with typical values
greater 2000 Bq kg-1. Also there may be possible high
signatures of 210Pb and 210Po in the tobacco leaves
and the cigarette samples smoked in the country.
This is a subject for future research consideration
given the fact that alpha radiation plays a major role
in the etiology of lung cancer. Iran. J. Radiat. Res.,
2011 8 (4): 201-206
Jibiri N, Biere P. Activity concentrations of 232Th, 226Ra and 40K and gamma radiation absorbed dose rate levels in farm soil for the production of different brands of cigarette tobacco smoked in Nigeria. Int J Radiat Res 2011; 8 (4) :201-206 URL: http://ijrr.com/article-1-681-en.html