Development of radiochemistry in Pakistan – 1960 to 2010

With the inception of Pakistan Atomic Energy Commission (PAEC) in 1956, peaceful uses of atomic energy commenced for the benefit of scientific community as well as masses of Pakistan. Radiochemistry played a vital role right from the beginning. The research and development in this field accelerated soon after the criticality of the first research reactor named as Pakistan Research Reactor (PARR- 1) at the Pakistan Institute of Nuclear Science and Technology (PINSTECH), Islamabad. The first radioisotope produced at PARR-1 for application in nuclear medicine was 131I. Later on, many other radioisotopes were prepared and radiopharmaceuticals were synthesised for their use in industry and hospitals. Besides providing pure radioactive tracers for nuclear medicine, radiochemistry also enhanced the detection limit of impurities at all stages of nuclear fuel cycle for power generation. In 1983, research in the field of nuclear data measurement began. The main aim was to identify suitable conditions for the production of radionuclides for cancer diagnostics, treatment and therapy. With the establishment of a second research reactor (PARR-2) at PINSTECH, research in neutron activation analysis, radioisotope production and separation studies gained more momentum and many research articles were published. Solvent extraction, adsorption and ion-exchange were the main routes of separation in those studies. Separation of heavy metals and treatment of waste generated in a nuclear power plant are other important aspects related to environmental restoration and nuclear waste management, where radiochemistry is required. In future, work in radiochemistry will be continued on similar lines to develop novel radiopharmaceuticals, identify indigenous schemes for nuclear waste management and work out intelligent procedures for material characterization for benefit to mankind, especially the people of Pakistan.

Measurement of natural radioactivity and dose rate assessment of terrestrial gamma radiation in the soil of southern Punjab, Pakistan

Activity concentrations of (226)Ra, (232)Th, (40)K and (137)Cs in soil samples collected from the most populous area of southern Punjab of Pakistan have been measured by gamma-ray spectrometry. The measured activity concentrations for these radionuclides are compared with the reported data from different other countries and it is found that measured activity concentrations are comparable with the worldwide measured average values reported by the UNSCEAR. Subsequently assessed radiological effects show that the mean radium equivalent activity (Ra(eq)) is 96.7 +/- 15.2 Bq kg(-1) and air absorbed dose rate (D) is 46.1 +/- 7.3 nGy h(-1). The values of internal and external radiation hazard indices are found to be less than unity. The annual effective radiation dose is calculated to be 0.28 +/- 0.05 mSv, which is well below the limit of 1.0 mSv y(-1) recommended by the International Commission on Radiological Protection, for the general public.

Measurement of natural radioactivity in bottled drinking water in Pakistan and consequent dose estimates

Natural radioactivity was determined in 11 different brands of commonly sold bottled drinking water in the federal capital Islamabad and Rawalpindi city of Pakistan using gamma spectrometry technique. Mean concentrations of 226Ra, 232Th and (40)K were found to be 11.3 +/- 2.3, 5.2 +/- 0.4 and 140.9 +/- 30.6 mBq l(-1), respectively. The annual cumulative effective doses due to all three natural radionuclides for different age groups of 1-5 y, 5-10 y, 10-15 y and adults (>or=18 y) were estimated to be 4.0, 3.4, 3.1 and 4.1 microSv y(-1), respectively. Among the three natural radionuclides, annual effective doses for all age groups from 226Ra were significant. Children in the age group of 1-5 y appeared to be at risk with respect to the annual effective doses from 226Ra as compared to the other age groups. Results obtained in this study are compared with the reported values from other countries of the world and it was observed that measured activity concentrations of three natural radionuclides in the bottled drinking water were lower than these values. Annual estimated effective doses for all four age groups from the intake of natural radionuclides in bottled drinking water were also found below the World Health Organisation (WHO) recommended limit of 0.1 mSv y(-1) as well as the average radiation dose of 0.29 mSv y(-1) received per head worldwide due to ingestion of natural radionuclides assessed by UNSCEAR (2000).

Crystal structure of picolinic acid hydrazide, C6H7N3O

C6H7N3O, monoclinic, C12/c1 (no. 15), a = 19.222(2) Å, b = 3.8987(4) Å, c = 18.115(2) Å, β = 107.095(2)°, V = 1297.6 Å3, Z = 8, Rgt(F) = 0.038, wRref(F2) = 0.122, T = 293 K.

Activity Concentration of 137Cs in soil samples from Punjab province (Pakistan) and estimation of gamma-ray dose rate for external exposure

Punjab is one of the most populated provinces of Pakistan having 34 districts. There is always a need to have baseline background level information about 137Cs and the corresponding gamma-ray doses to the population. In this respect, soil samples were collected to a depth of 30-50 cm from all 34 district headquarters of the Punjab province of Pakistan and 137Cs activity concentrations were measured. 137Cs activity concentration was found to be in the range from 1.1 +/- 1.0 to 5.3 +/- 2.5 Bq kg(-1). The average value of estimated external gamma-ray dose rate from all 34 districts of Punjab province was computed to be 0.18 +/- 0.07 nSv h(-1) from 137Cs in soil samples. The measured 137Cs activity concentration range was compared with the reported ranges in the literature from some of the other locations in the world. Results obtained in this study show that 137Cs concentration is of a lower level in the investigated area. The average value of estimated external effective dose rate is found far below the dose rate limit of 1.0 mSv y(-1) for members of the general public recommended by the International Commission on Radiological Protection (ICRP) as well as the external gamma radiation dose of 0.48 mSv y(-1) received per head from the natural sources of radiation assessed by UNSCEAR (2000). It is concluded that 137Cs soil contamination does not pose radiation hazards to the population in the investigated areas.

Measurements of activity concentrations of naturally occurring radionuclides in soil samples from Punjab province of Pakistan and assessment of radiological hazards

The natural level of radioactivity in soil is one of the major causes of external gamma rays exposure. It was considered imperative to measure gamma-ray activity concentrations due to naturally occurring, potentially hazardous radionuclides from 232Th, 226Ra and 40K in soil samples from Punjab, the most populated province of Pakistan. The activity concentrations were measured in soil samples collected from all 34 district headquarters of Punjab province using a P-type coaxial high purity germanium (HPGe)-based gamma-ray spectrometer having a relative efficiency of 60%. The mean activity concentrations for 232Th, 226Ra and 40K were found to be 41 +/- 8, 35 +/- 7 and 615 +/- 143 Bq kg(-1), respectively in soil samples from all 34 district headquarters of Punjab. The mean values of radium equivalent index (Ra(eq)) and total annual external gamma radiation dose were found to be 141 +/- 27 Bq kg(-1)and 0.38 mSv, respectively. Since these estimated radiological impact assessment factors are lower than the recommended values there seems to be no potential radiological health hazard associated with the soils from the district headquarters in the Punjab province of Pakistan. Geological studies show that most of the soils in Punjab have developed on the extensive fluviatile deposits of five rivers and a stable ratio of natural activity concentrations is observed in soil samples of the areas under study.

Determination of natural radioactivity in building materials used in the Rawalpindi/Islamabad area by gamma-ray spectrometry and instrumental neutron activation analysis

Samples of sand and manufactured building materials collected from the Rawalpindi/Islamabad area have been analyzed for the primordial natural radionuclides 238U, 232Th and 40K using gamma-ray spectrometry. The uranium and thorium contents have also been determined by instrumental neutron activation analysis (INAA). The specific activities of these radionuclides in the samples are compared with those of the world averages for soil. The comparison shows that, of the nine samples analyzed, only the three brick samples have higher activities than the world averages for soil. The specific activities in these materials, having a radium equivalent activity of less than 370 Bq kg-1, when evaluated for radiological effects show that all materials meet the external gamma-ray dose limitation of 1.5 mSv y-1. The gamma-spectrometric and INAA techniques complemented each other well in this study.

Cholinergic agents structurally related to furtrethonium. 3. Synthesis and antimuscarinic activity of a series of N-(5-methyl-2-furfuryl and-tiophenyl)-dialkyl amines and of 2-dimethylamino methyl-4-(1'-substituted-acetoxy-methyl)-1,3-dioxolanes

The introduction of an homologous series of cyclic amines at position 2 of 5-methylfurane and its isoster 5-methylthiophene induced a weak antagonist behaviour, probably depending on the steric hindrance of the substituents at the nitrogen, in the case of the cardiac tissue. Surprisingly, when evaluated on guinea-pig ileum preparatons, these compounds showed non-muscarinic effects, not-related either to nicotinic or istaminergic effects, the nature of which awaits to be explained. Substitution of the furane ring on the structure of the lead 2a, b, obtained in a previous study, with the bioisoster 1,3-dioxolane moiety gave potent but not selective analogues (17 and 18).

Health evaluation of an aerosol formed in the fumes from mild steel welding electrodes

Welding is one of the processes which cause multivarious problems to health. It requires considerable attention because of its severe hazards. During welding very harmful fumes and heat are emitted which have adverse effects on the health of the welder and people working in his vicinity. In the present work microfibre glass filter paper (GF/A) was found to be the preferable media for sampling of the fumes from mild steel electric welding electrodes for the evaluation of the trace elemental composition of the fumes. Using neutron activation analysis considerable amounts of the most harmful elements such as Ba, Co, Cr, Sb, Rb, Sc, As and Fe were observed.