Measurement of 222Rn gas Concentrations and Radon Exhalation Rates in Some Cigarettes Tobacco Samples

Twelve cigarette tobacco samples of various brands and origins were gathered from local markets of Iraq. . The CRn was determined utilizing CR-39 track detectors which were exposed to the various brands of cigarettes tobacco for 45 days. The results demonstrated that the highest value of 222 Rn concentration was )157 Bq/m 3 ( in Macbeth cigarette sample of Brazilian origin and the lowest value of CRn was (76.3 Bq/m 3 ( in Sumer cigarette sample of Iraqi origin,with an average value of (106.53±22.3 Bq/m 3 ). The outcomes have demonstrated that cigarettes of a Brazilian origin contain higher CRn than other studied samples, however, it is still less than some other average values given in the literatures.


Introduction
Numerous sorts of tobacco are grown for a variety of uses. The sorts of tobacco vary according to tobacco classes according to plant density, manipulation of nitrogen fertilization, height, time of topping, harvesting and curing which is normally and favorably influence the usability of the cured leaves for the specific products [1]. It has been known for more than twenty years that a wide scope of tobacco contains radioactive 210 Pb which emits negative beta particles and radioactive 210 Po which emits alpha particles. Soil contains radioactive elements that could be due to phosphate ore which is used as a fertilizer in tobacco fields and 210 Pb. [2].Thus the current work is concerned with the determination of the 222 Rn concentrations (C Rn ) and the radon surface exhalation rates in some cigarettes tobacco samples accessible in the local Iraqi markets.

1-Materials and Method
Twelve cigarettes samples of various brands were gathered from local Iraqi markets . The samples were grinded and sifted with special sieve of a grain size of approximately 650µm.The samples were weighted to about (ten g) ) approximately 25 cigarettes( and placed in a cylindrical plastic cup. Figure 1 shows the dimensions of this plastic cylinder. Pieces of (1cm²) CR-39 track detector were fixed in the top cover of the plastic cylinder . The detectors will be exposed to 222 Rn produced from the samples for 45 days,so as to measure the radioactivity from the samples. The 222 Rn concentration (C Rn ) in the studied cigarettes tobacco samples were obtained utilizing the usual method,i.e. ,by the comparison between (ρ) registered by the detectors of the samples and that of the standard cigarettes tobacco samples [4] :

2-Determination of the 222 Rn exhalation rate (RER) in cigarettes tobacco samples
The radon exhalation rate (RER) was calculated utilizing the relation [5]: C: integrated radon exposure. V: volume of air in the cylinder ,λ: decay constant for 222 Rn ,A : surface area of the sample , T : exposure time .

3-Results and Discussion
In the present work, the (C Rn ) from cigarettes tobacco samples for 12 various cigarettes brands were measured utilizing CR-39 track detector. The outcomes of the measurements for C Rn in the studied tobacco samples which were collected from the local Iraqi markets are presented in Table 1 and demonstrated in Figure 2. The obtained data revealed that Macbeth sample, which is of Brazilian origin, recorded the highest C Rn with the value of (157 Bq/m³).. While, Sumer sample, which is an Iraqi cigarette brand, recorded the lowest C Rn with the value of (76.3 Bq/m³).The radon exhalation rate (RER) was found to be (4255.79 µBq/m 2 h)for the Macbeth sample, while that for Sumer sample was (8756.99 µBq/m 2 h). The scope of outcomes (76.3-157 Bq/m³) for C Rn in tobacco samples obtained in the present work, was found to be within the scope of outcomes (20.2-364 Bq/m³) given Ridha and Hasan [6] . The present average value of (106.53 Bq/m³) was obtained in this work.

4-Conclusion
The present work have demonstrated that the C Rn of the studied cigarettes tobacco samples were in the scope of (76.3-157 Bq/m 3 ), with an average value of (106.53 Bq/m 3 ) which is, in general, lower than the outcomes of some other similar studies given in the literatures. Nonetheless, it is well known that 222 Rn is the essential reason lung cancer, and for smokers the risk is higher, since it was previously observed a strong synergism between smoking and 222 Rn exposure.