Seasonal variation of radon, thoron and their progeny levels in dwellings of Haryana and Western Uttar Pradesh

Radon and thoron are invisible, odorless, heavy and radioactive gases which are ubiquitously present in dwellings and in the environment. In the present work, seasonal variation of indoor radon, thoron and their progeny concentrations has been studied in the dwellings of industrially polluted cities in District Faridabad, Haryana and District Mathura in Uttar Pradesh. LR-115, Type-II [Kodak Pathe, France], peelable, plastic track detectors commonly known as solid state nuclear track detectors [SSNTDs] were used to measure the radon thoron concentration over long integrated times. The measurements were carried out in the mixed field of radon and thoron and the detectors were exposed for about 90 days. The average value of radon and thoron concentration in the dwellings varied from 23.5 Bq/m[3] to 65.2 Bq/m[3] and 9.8 Bq/m[3] to 18.7 Bq/m3 respectively in different seasons. The average annual exposure and annual effective dose in living rooms due to radon and thoron progeny was estimated to be 0.195 WLM [working level month] and 0.74 mSv respectively. The average life time fatality risk of lung cancer from the chronic radon and thoron progeny exposure was estimated to be 5.8 ' 10[-3] [0.58%]. The seasonal variations of measured radon levels in the environment of LPG bottling plant, radon-thoron levels and inhalation dose due to radon and thoron and their progeny in dwellings indicate that the levels were higher in winter [October to January] than in summer [April to July]

3-Dimensional conformal radiotherapy versus intensity modulated radiotherapy for localized prostate cancer: dosimetric and radiobiologic analysis

To analyze the dosimetric and radio biologic advantages between intensity modulated radiotherapy [IMRT] and 3 dimensional conformal radiotherapy [3DCRT] and selection of optimal photon energy for IMRT treatments. 24 patients with localized prostate carcinoma were planned for 3DCRT and IMRT techniques. Radiation dose of 54 Gy with 2 Gy/fraction, was planned to Planning target volume [PTV1] [prostate + seminal vesicle + 1 cm margin] and 72 Gy to PTV2 [prostate + 1 cm margin] respectively. 3DCRT planning was done using 15 MV photon beam while IMRT plans were created using 6 MV and 15MV photons. Treatment plans were analyzed using mean, median, dose maximum and cumulative dose volume histogram for PTV1, PTV2, bladder, and rectum. Tumor control probability [TCP] was calculated for prostate. Normal tissue complication probability [NTCP] was calculated for bladder, rectum, and head of femur. Mean dose to prostate was 72.79 +/- 0.18 Gy for IMRT 15 MV, 72.16 +/- 0.27 Gy for 3DCRT and 72.48 +/- 0.19 Gy for IMRT 6 MV. TCP was greater for IMRT 15 MV followed by IMRT 6 MV. The mean value of NTCP was significantly lower [p = 0.0015] for IMRT 6 MV compared to 3DCRT for rectum while for bladder all were comparable. IMRT techniques shows superiority in sparing surrounding critical organs, thus reducing normal tissue complication rates while maintaining the same or higher tumor control probability. No significant difference was observed between IMRT 6 MV and IMRT 15 MV techniques.

Alpha radioactivity in Indian cement samples

The essential constituents of cements like lime, silica and alumina are derived from earth's crust in which radioactive elements like uranium, thorium etc are also present in varying amounts almost everywhere. These two elements are considered as the parent elements of uranium and thorium radioactive decay series in which radon and thoron are produced respectively as decay products. In the present study the samples of ordinary Portland cement [OPC], Portland pozzolana cement [PPC] and some other cementious finishing materials like white cement, Plaster of Paris [POP], cement putty etc were collected and analysed for radium and radon concentrations along with radon exhalation rates. Alpha sensitive LR-115 Type II plastic track detectors commonly known as "Solid State Nuclear Track Detectors" were used to measure the radium and radon concentration. The alpha particles emitted from the radon causes the radiation damaged tracks. The Chemical etching in NaOH at 60°C for about 90 minutes was done to reveal these latent tracks, which were then scanned and counted by an optical microscope of suitable magnification. By calculating the track density of registered tracks, the radon and radium concentrations along with exhalation rate of radon, were determined using required formulae. The radon and radium concentration in various brands of cements found to vary from 333 +/- 9.9 to 506 +/- 13.3 Bq m[-3] and from 3.7 +/- 0.1 to 5.6 +/- 0.2 Bq kg[-1] while in various cementious finishing materials used in the construction, these were found to vary from 378 +/- 19.7 to 550 +/- 9.8 Bq m[-3] and from 4.2 +/- 0.2 to 6.1 +/- 0.1 Bq Kg[-1], respectively. Based on the data the mass and surface exhalation rates were also calculated. The measurements indicate that there is marginal variation of the concentration of radium and radon in various brands of cements in India with lower levels in the cement samples having red oxide and higher levels in fly ash based cement samples but overall concentration levels of radon and radium are lower than that of average global values

Radiological risk assessment of use of phosphate fertilizers in soil

The radiological impact of the use of phosphate fertilizers in soil is due to the internal irradiation of the lung by the alpha particles, short lived radon-thoron progeny and the external irradiation of the body by gamma rays emitted from radionuclides in situ. This paper describes the results of gamma spectrometric measurements of the concentration of the natural radionuclides namely [226]Ra, [232]Th and [40]K in the soil samples collected from the fields where a variety of phosphate fertilizers are being used by the farmers to enhance the crop yield. The experimental work utilizes actual measurements of [226]Ra, [232]Th and [40]K using gamma spectrometry and radon concentration and exhalation rates measurements using solid state nuclear track [LR-115, Type- II plastic] detectors to asses a first order exposure risk for the persons working in the fields where lot of fertilizers are being used to enhance crop yield in terms of occupational exposure. The concentration of Radium, Thorium and Potassium in the mixed soil sample from crop fields is 16.2 +/- 0.22, 68.1 +/- 1.44 and 875.0 +/- 9.68 Bq/kg, where as in barren soil sample is 9.1 +/- 0.13, 59.4 +/- 1.45 and 668.4 +/- 8.01 Bq/kg respectively. The radium equivalent activity [Ra[eq]] in the mixed soil sample from crop fields is 225.9 Bq/kg, where as in barren soil sample is 193.1 Bq/kg. The values of absorbed dose and annual effective dose [indoors and outdoors] are found to vary from 90.87 nGyh[-1] to 119.71nGyh[-1], 0.45mSv/y to 0.59mSv/y and 0.11mSv/y to 0.15mSv/y respectively in soil sample from crop fields, whereas the value of absorbed dose and annual effective dose [indoors and outdoors] is 92.29 nGyh[-1], 0.45mSv/y, 0.11 respectively in soil sample collected from barren land. The radon concentration and exhalation rates have also been reported. The activity concentration, exhalation rate and absorbed dose were found to increase substantially with the use of phosphate fertilizers and it varies from sample to sample. The radium equivalent activities in all the soil samples were found to be lower than the limit [370 Bq/kg] set in the Organization for Economic Cooperation and Development [OECD] report and the dose equivalent is within the safe limit of 1mSv/y

Alpha activity in Indian thermal springs

Dissolved radon is contained in natural water due to primordial uranium in rocks and soils with which it comes in contact. There is dual exposure from radon in water i.e. due to inhalation of the radon released from the water into the ambient air and through ingestion when water is used for drinking. As radon contaminated water adversely affects the health, it is therefore fundamental from health and hygiene point of view to measure radium concentration and radon exhalation rates in water. LR-115, Type- II plastic track detectors were used to measure the radium concentration and radon exhalation rate in water samples collected from various thermal springs. The alpha tracks registered were counted by optical microscope at suitable magnification and converted into radium concentration and subsequently radon exhalation rates were measured. The radon concentration emanated from water samples [air borne] varied from 84 Bq m[-3] to 827 Bq m[-3] with an average of 429 +/- 12.72 Bqm[-3] and the dissolved radon concentration varied from 5.65 Bq l[-1] to 55.66 Bq l[-1] with an average of 28.88 +/- 0.85 Bq l[-1]. The radon mass exhalation rates varied from 2.37 mBq kg[-1]hr[-1] to 23.39 mBq kg[-1]hr[-1] with an average of 12.14 +/- 0.36 mBq kg[-1]hr[-1] and surface exhalation rates from 52.34 mBq m[-2]hr[-1] to 515.29 mBq m[-2]hr[-1] with an average of 267.36 +/- 7.93 from different thermal spring water samples. The radium concentration varied from 0.30 Bq l[-1] to 2.93 Bq l[-1] with an average of 1.52 +/- 0.045 Bq l[-1]. Results indicate that the thermal spring water, which is also being used for drinking, is safe as far as radium concentration is concerned with the exception of a few isolated thermal spring sources

Measurement of inhalation dose due to radon and its progeny in an oil refinery and its dwellings

Radon, an invisible, odorless, heaviest [nine times heavier than air] and radioactive gas is an aberration [the only gas in the long decay chain of heavy metal elements]. It is ubiquitously present in dwellings and in the environment. Humans receive the greatest radiation dose in their homes. That's where they spend most time - typically 70%, more for small children. Recent worldwide surveys reveal that an average person receives each year more radiation from radon than from all other natural or man-made sources combined. Over the years, the radiation exposure accumulated at home may exceed the exposure of uranium miners and lead to lung disorders. Therefore it is fundamental and justified to make a quantitative assessment of the radon in dwellings and the environment of work place. In this study, measurement of radon and its progeny levels was carried out in the environment of an oil refinery. Besides, radon and its progeny levels were also measured in the dwellings situated on the refinery premises and the dwellings in the city for comparison. Materials and LR-115, Type- II [Kodak Pathe, France], plastic track detectors commonly known as solid state nuclear track detectors [SSNTDs] were used to measure the radon concentration over long integrated times. Alpha particles emitted from radon cause radiation damage tracks, which were subsequently revealed by chemical etching in NaOH. These alpha tracks registered were counted by optical microscope at suitable magnification and converted into radon concentration. The geometric means [GM] of potential alpha energy concentration [PAEC], Equilibrium Equivalent Concentration of radon [EEC value], annual exposure and annual effective dose in the environment of refinery premises was 10.09 mWL, 93.43 Bq m-3, 0.41 WLM and 1.61 mSv, in refinery dwellings 12.21 mWL, 112.96 Bq m-3, 0.50 WLM and 1.94 mSv and in city dwellings 8.24 mWL, 76.23 Bq m-3, 0.34 WLM and 1.31 mSv respectively. The dose levels in the refinery premises were found to be marginally below the ICRP recommendations. The radon and its progeny levels were higher in the dwellings of refinery township as compared to the city dwellings. While studying seasonal variation, it was found that the measured values of radon and its progeny levels were higher in winter [November to February] than in summer [May to August]. This study showed that the presence of fossil fuels like natural gas, LPG etc. in the environment had resulted into higher levels of radon and its progeny in the refinery dwellings

Radon monitoring in gas turbine and thermal power station: a comparative study

In this study, measurement of indoor radon and its progeny levels was carried out in Gas Turbine Power Station in Haryana [India], where natural gas is used as fuel. For comparison, the results of a study carried out in thermal power plant in Haryana are also presented. Radon being a ubiquitous air pollutant has global impact and its monitoring in the environment at work places is essential from health and hygiene point of view. Materials and LR-115, Type- II [Kodak Pathe, France], plastic track detectors commonly known as solid state nuclear track detectors [SSNTDs] were used to measure the radon concentration over long integrated times. Alpha particles emitted from radon cause radiation damage tracks, which were subsequently revealed by chemical etching in NaOH. These alpha tracks registered were counted by optical microscope at suitable magnification and converted into radon concentration. The radon levels measured at various locations were moderate to high and thus unsafe from health point of view. The potential alpha energy concentration [PAEC], radon levels [EEC], annual exposure, annual effective dose in the Gas Turbine Power Plant varied from 4.14 mWL to 26.7 mWL, 38.3 Bq m-3 to 247.6 Bq m-3, 0.17 WLM to 1.10 WLM and 0.66 mSv to 4.25 mSv respectively. In gas turbine power plant, the radon levels were found to be lower as compared with thermal power plant. In thermal power plant a lot of coal is being burnt which contains radionuclides. Coal fired plants release more radioactive waste which is hazardous into the air than gas power plants of equivalent capacity