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PubMed1996

Radon in Devon and Cornwall and paediatric malignancies.

Exposure to radon in dwellings may cause cancer including paediatric malignancies. Devon and Cornwall have the highest exposure to radon of the counties of England. However, within these counties there is considerable variation in exposure. Exposure to radon in the 283 postcode sectors of the two counties has been published. The incidence of childhood malignancies between 1976 and 1985 was studied to compare postcode sectors of radon exposures > or = 100 Bq/m3 with sectors < 100 Bq/m3. No significant difference in the incidence rate of 106.7 per million child years in the high radon postcode sectors and 121.7 in the low (P = 0.29) was found. When the incidences of individual tumours were examined, a significantly increased rate of neuroblastoma (P = 0.02) and a non-significant increased rate of acute myeloid leukaemia were found in the high exposure postcode sectors. No association between radon exposure and overall rate of childhood malignancy was found.

Acute Disease↗
PubMed1996

Radon and childhood cancers.

The effective radiation doses received by children living in high radon areas are similar to those which have been associated with an excess risk of malignant disease elsewhere. However, the only cancer known to be associated with radon is lung cancer--a disease which is not a condition of childhood. Thorne and his colleagues have conducted a study which could have demonstrated an excess of childhood malignancy only if the risk associated with radon was very high. The risk to health of high levels of radon in the environment remains uncertain. The United Kingdom Case Control Study of Childhood Cancers, under the chairmanship of Sir Richard Doll, is assessing risk from many factors including measured radon exposure and it is with great interest that we await the results.

Air Pollutants, Radioactive↗
PubMedDate not supplied

Locating a "hot spot" in the lungs when using an array of four HPGe detectors.

Considerable errors in the activity determination in lungs can be induced for the case of a "hot spot". Modern lung counter systems use several HPGe detectors, and the count rate ratios of the detectors can be used to locate the "hot spot" and apply correction algorithms. Some criteria for location determination of a point source in the lungs were investigated, and it is shown that an average error of up to about 10% can be achieved.

Aerosols↗
PubMed2004

Effects of heating on the emanation rates of radon-222 from a suite of natural minerals.

The emanating power of radon provides information on the internal structure of a mineral and the radiation damage caused by the decay of 238U, 235U and 232Th (and their daughters) that are present in the mineral. The concentration of 222Rn in groundwater is primarily controlled by the concentration of U and Th in the underlying rocks, as well as the emanation coefficient for that particular rock. The variations in the emanation coefficient for 222Rn caused when subsurface rocks are subjected to tectonic forces results in changes in 222Rn in groundwater. Increased emanation rates of radon from a mineral grain can potentially alter the 238U-206Pb, 235U-207Pb and 232Th-208Pb chronological clocks. We have measured radon emanation coefficients on a suite of minerals comprised of one oxide (uraninite), three silicates (thorite, zircon, and cerite) and one phosphate (monazite) at room temperature and after heating at 200 degrees C and 600 degrees C. Annealing of some of the nuclear tracks within a mineral significantly reduces the emanation rates of radon in these minerals, suggesting that the tracks created by decay events serve as conduit pathways for the release of 222Rn. Higher emanation rates of 222Rn from mineral grains that are surrounded by liquid as compared to air indicate that a major portion of the escaping 222Rn in air gets embedded into adjacent mineral grains and/or opposite walls of a pore.

Air Pollution, Radioactive↗
PubMed2004

Beryllium-7 and solar activity.

A very low concentration of (7)Be in air at Thessaloniki, Northern Greece (40 degrees 38'N, 22 degrees 58'E) was recorded on November 9, 2003 following a strong event of solar wind that occurred on October 29, 2003.

Air Pollutants, Radioactive↗
PubMed2004

Intercomparison of sampling and measurement of 7Be in air at four high-altitude locations in Europe.

For several years 7Be measurements have been conducted at high-altitude stations in Austria (Sonnblick, 3106 m), Switzerland (Jungfraujoch, 3580 m), Germany (Zugspitze, 2962 m), and Italy (Mt. Cimone, 2165 m) with the aim to support a study on vertical ozone transport in the Alps (VOTALP project). Aerosol samples, collected on filtering media with high volume samplers, are analysed for 7Be by high-resolution gamma-spectrometry. Prior to evaluation of the 7Be time series of the four stations, both sampling and measurement procedures were checked for comparability. The results of an intercomparison exercise performed within the mentioned project are reported.

Air Pollutants, Radioactive↗
PubMed2005

Temporal changes of 7 Be and 210 Pb concentrations in surface air at temperate latitudes 40 degrees N.

Atmospheric concentrations of (7)Be and (210)Pb were measured for 15 years (1987--2001) in ground-level air at Thessaloniki, Northern Greece (40 degrees 38'N, 22 degrees 58'E). Mean activity concentrations of (7)Be and (210)Pb were 5.02 mBqm(-3) and 664 microBqm(-3), respectively, characteristic of the latitude of 40 degrees N. Monthly atmospheric concentrations of (7)Be showed a strong seasonal trend with the highest values being observed in the summer and the lowest in the winter period. Multiple regression analysis of the data of (7)Be concentrations and a number of meteorological parameters revealed that the sunspot number and temperature are the most significant parameters affecting the concentrations of (7)Be in surface air. The observed strong positive correlation between the mean monthly concentrations of (7)Be and the temperature confirms that the increased rate of vertical transport within the troposphere, especially during the warm months, has as a result to carry down to the surface layer air masses enriched in (7)Be. Highest values of the mean monthly atmospheric concentrations of (210)Pb were observed in the autumn and lowest in the spring period. The positive correlation that was observed between (210)Pb and (7)Be concentrations during the summer months suggests that these two radionuclides could be used together as tracers of environmental processes.

Air Pollutants, Radioactive↗
PubMed2005

Atmospheric 14 C CO 2 variations in Japan during 1982--1999 based on 14 C measurements of rice grains.

(14)C in rice grains is a useful tracer of atmospheric (14)C(CO(2)). (14)C measurement in rice grains for 17 years during 1982--1999 reveals the following. There is negative correlation between Delta(14)C and the population densities of localities in Japan. Under-populated areas in the northern area of Japan and Okinawa remained clean in the 1990s. The (14)C(CO(2)) decline rates at those areas are near to that of Shauinsland. A latitudinal effect due to Chinese nuclear tests is observed in 1982. Small Seuss effects is observed at the middle latitudes in East Asia after 1995.

Air↗
PubMed2005

Concentration and characteristics of depleted uranium in water, air and biological samples collected in Serbia and Montenegro.

During the Balkan conflicts, in 1995 and 1999, depleted uranium (DU) rounds were employed and were left in the battlefield. Health concern is related to the risk arising from contamination of the environment with DU penetrators and dust. In order to evaluate the impact of DU on the environment and population in Serbia and Montenegro, radiological surveys of DU in water, air and biological samples were carried out over the period 27 October-5 November 2001. The uranium isotopic concentrations in biological samples collected in Serbia and Montenegro, mainly lichens and barks, were found to be in the range of 0.67-704 Bqkg(-1) for (238)U, 0.48-93.9 Bqkg(-1) for (234)U and 0.02-12.2 Bqkg(-1) for (235)U, showing uranium levels to be higher than in the samples collected at the control sites. Moreover, (236)U was detectable in some of the samples. The isotopic ratios of (234)U/(238)U showed DU to be detectable in many biological samples at all examined sites, especially in Montenegro, indicating widespread ground-surface DU contamination, albeit at very low level. The uranium isotopic concentrations in air obtained from the air filter samples collected in Serbia and Montenegro were found to be in the range of 1.99-42.1 microBqm(-3) for (238)U, 0.96-38.0 microBqm(-3) for (234)U, and 0.05-1.83 microBqm(-3) for (235)U, being in the typical range of natural uranium values. Thus said, most of the air samples are DU positive, this fact agreeing well with the widespread DU contamination detected in the biological samples. The uranium concentrations in water samples collected in Serbia and Montenegro were found to be in the range of 0.40-21.9 mBql(-1) for (238)U, 0.27-28.1 mBql(-1) for (234)U, and 0.01-0.88 mBql(-1) for (235)U, these values being much lower than those in mineral water found in central Italy and below the WHO guideline for drinking water. From a radiotoxicological point of view, at this moment there is no significant radiological risk related to these investigated sites in terms of possible DU contamination of water, air and/or plants.

Air Pollutants, Radioactive↗
PubMed2005

About the effectiveness of the ABPD methods in air-borne alpha-activity monitoring.

A modified version of the alpha-beta-pseudo-coincidence-difference (ABPD-M) method is proposed with a view to suppressing natural background radiation when measuring the transuranium radionuclide (TRU) content in aerosol samples. It is shown that complementing the traditional "pseudo-coincidence" method with a treatment of (comparatively) fast beta-alpha coincidences provides a means to significantly improve the suppression of background fluctuations and the accuracy of measurement results in comparison with the traditional method.

Air Pollutants, Radioactive↗
PubMed2005

A geographic information systems (GIS) and spatial modeling approach to assessing indoor radon potential at local level.

This study integrates residential radon data from previous studies in Southern California (USA), into a geographic information system (GIS) linked with statistical techniques. A difference (p<0.05) is found in the indoor radon in residences grouped by radon-potential zones. Using a novel Monte Carlo approach, we found that the mean distance from elevated-radon residences (concentration>74 Bq m(-3)) to epicenters of large (> 4 Richter) earthquakes was smaller (p<0.0001) than the average residence-to-epicenter distance, suggesting an association between the elevated indoor-radon and seismic activities.

Air Pollutants, Radioactive↗
PubMed2006

Retrospective estimation of the concentration of 241Pu in air sampled at a Belgrade site following the Chernobyl accident.

The surface air activity concentration of 241Pu for the period May 01-15, 1986, for a monitoring site in Vinca, Belgrade was retrospectively estimated. The results were obtained by re-measurement of plutonium fraction alpha-spectrometric sources, with 236Pu as a tracer, used almost 13 years earlier for the determination of (239,240)Pu concentration in surface air immediately after the Chernobyl accident. The estimated 241Pu concentration, based on the 241Am in-growth method for air samples, ranged from 240 to 7800 microBq/m3. The average activity ratio 241Pu/(239,240)Pu originating from the Chernobyl accident at Belgrade site was approximately 100 at the collection time.

Air Pollutants, Radioactive↗
PubMed2006

Radon measurements with a PIN photodiode.

Silicon photodiodes are well suited to detect alphas coming from different sources as neutron reactions or radon daughters. In this work a radon in air detecting device, using an 18x18 mm silicon PIN photodiode is studied. The ionized airborne decay products formed during radon diffusion were focused by an accelerating high voltage to the PIN surface. Several conducting rings were disposed inside a cylindrical PVC vessel in such a way that they reproduced the electric field created by a punctual charge located behind PIN position. Alpha spectra coming from the neutral and ionized species deposited on the PIN surface, dominated by 218Po and 214Po progeny peaks, were recorded for varying conditions. Those include radon concentration from a Pylon source, high voltage (thousands of volts) and PIN inverse bias voltage. Different parameters such as temperature and humidity were also registered during data acquisition. The increase in the particle collection efficiency with respect to zero electric field was compared with the corresponding to a parallel plates configuration. A discussion is made in terms of the most appropriate voltages for different radon concentrations.

Air Pollutants, Radioactive↗
PubMed2006

Optimization of counting times for short-lived gamma-ray emitters in air filter samples.

A methodology for the optimization of the counting times in a series of measurements of gamma-ray emitters in air filters is presented. In the optimal measurement regime in measurements of all the filters in a batch, the same minimum detectable activity is attained. It is shown how the number of filters, the properties of the gamma-ray emitter and the equipment influence the measurement time of the batch of filters and the minimum detectable activity attained.

Air Pollutants, Radioactive↗
PubMed2006

Radon activity concentration--a Euromet and BIPM supplementary comparison.

For the first time, a comparison of radon activity concentration in air has been performed within the scope of Euromet. In the project 657, 'Comparison of calibration facilities for the radon activity concentration,' 12 participants from 9 countries compared different radon reference atmospheres at 1, 3 and 10 k Bq m-3 via a transfer standard. The comparison was listed as BIPM supplementary comparison EUROMET.RI(II)-S1. The results of most participants are correlated due to common traceability to one single radon gas standard producer. This makes a careful correlation analysis necessary to achieve an appropriate comparison reference value. The results of the comparison as well as the complex analysis of the correlated set of data is presented and discussed.

Air Pollutants, Radioactive↗
PubMed2006

Low-level activity measurement of 131Xem, 133Xem, 135Xe and 133Xe in atmospheric air samples using high-resolution dual X-gamma spectrometry.

High-resolution dual X and gamma spectrometry has been optimized to improve the sensitivity in analyzing radioxenon from environmental samples, especially for the metastable isotopes (131Xem and 133Xem). The full-energy peak (FEP) efficiency curve in the 20-700 keV range has been established with a global uncertainty better than +/-3% using a Monte Carlo simulation. The minimum detectable activity concentrations (MDC) achievable at the laboratory for 131Xem, 133Xem, 133Xe and 135Xe are presented and the influence of 133Xe activity on the metastable radioxenon MDCs is evaluated.

Air Pollutants, Radioactive↗
PubMed2006

Impact of phosphate industry on the environment: a case study.

This paper presents results obtained from studying the impact of the Syrian phosphate industry on the environment. This work is based on evaluating naturally occurring radionuclide concentrations in the surrounding environment at the locations of this industry, viz. mines, phosphate fertilizers factory and phosphate export platforms. Air particulates, soil, water (river, lake and sea water), biota and plant samples were collected and analyzed. Natural radionuclides ((226)Ra, (nat)U, (210)Po, (210)Pb) were determined by means of low background gamma spectrometry and alpha spectrometry. The results showed that the distribution and enhancement of natural radionuclides in the surrounding environment in these three locations are mainly due to fallout of phosphate dust generated during loading and processing of phosphate ore. The extent of contamination was related to climate conditions. Radon gas and its daughters generated from phosphate ores were found to be the main source of enhanced concentrations of (210)Po and (210)Pb in soil and leafy plants. These results can be considered as baseline data and can be used to prove the effectiveness of any future pollution controls adopted.

Air Pollutants, Radioactive↗