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Selenium (Se) is an element that, in trace quantities, plays an important role in the normal function of a number of biological processes in humans. Many studies have demonstrated that selenium deficiency in the body may contribute to an increased risk for certain neoplastic, cardiovascular, osseous, and nervous system diseases including retardation of bone formation. However, at higher concentrations Se is cytotoxic. For these reasons it is desirable to have a means of monitoring selenium concentration in humans.This paper presents the outcome of a feasibility study carried out for measuring selenium in humans using in vivo neutron activation analysis (IVNAA). In this technique a small dose of neutrons is delivered to the organ of interest, the neutrons are readily captured by the target nuclei, and the γ-rays given off are detected outside of the body. For the present study, human hand (bone) tissue equivalent phantoms were prepared with varying amounts of Se. These were irradiated by a low energy fast neutron beam produced by the (7)Li(p,n)(7)Be reaction employing the high beam current Tandetron accelerator. The counting data saved using a 4π NaI(TI) detection system were analyzed. The selenium was detected via the neutron capture reaction, (76)Se(n,γ)(77 m)Se, whereas calcium was detected through the (48)Ca(n,γ)(49)Ca reaction for the purpose of normalization of the Se signals to the calcium signals. From the calibration lines drawn between Se/Ca concentrations and Se/Ca counts ratio, the minimum detection limits (MDLs) were computed for two sets of phantoms irradiated under different irradiation parameters.In this study the optimized MDL value was determined to be 81 ng g(-1) (Se/phantom mass) for an equivalent dose of 188 mSv to the phantom. This MDL was found at least 10 times lower than the reported data on Se concentration measured in bone tissues. It was concluded that the NAA technique would be a feasible means of performing in vivo measurements of selenium in humans. Currently the data on in vivo measurement of selenium in humans are limited; the results of the present study would greatly contribute to the present data.

7Be is a cosmogenic radionuclide with a half-life of 53.3 d produced mostly in the stratosphere by cosmic ray spallation of nitrogen and oxygen and entering the lower troposphere by atmospheric circulation processes. 7Be emits gamma rays of energy 477.6 keV and its concentration in the ambient air can be measured by gamma spectrometry. In the present study, the activity concentration of 7Be in outdoor ambient air of Lahore city, Pakistan, has been measured employing two air samplers and using a high purity germanium [HP(Ge)] detector. The 7Be activity concentration was found in the range from 1.6 to 11.3 mBq m(-3) with a mean value of 5.4 mBq m(-3).

In order to assess the degree of radon awareness in the general public in the provincial capital Lahore of Punjab province of Pakistan, a survey was conducted in all nine municipal towns of Lahore city. In this regard, volunteers from three Universities and six Colleges were deputed to collect data from hospitals, educational institutes, business points, markets, residential areas, public offices and private sector organisations. About 400 un-educated and educated persons of various educational background from each municipal town participated in this survey and their responses were recorded on the questionnaire prepared for this purpose. In this way, a total of 3600 persons participated in this survey. Results of this survey imply that on average, only 30.9% participants were scientifically aware of radon. These results suggest that a nationwide mass media campaign may be launched by the Federal Ministry of Environment, Provincial Environment Protection Agency and Community Development Department to educate the general public in this respect at the union council level about hazards of radon to avoid its harmful effects.