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PubMed2006

[Radon in Tunisian buildings].

Radon is a natural radioactive gas produced by decay of uranium and radium present in soils. Diluted in air, in confined atmospheres, it may accumulate in high concentrations. Inhalation of radon and its progeny is thought to increase lung cancer risk. For the first time, air radon concentrations were determined in 1151 dwellings situated in all the inhabited regions of Tunisia, using open alpha-track dosimeters exposed during two months. The median of 1864 measurements was 36 Bq m(-3) (with a maximum of 512 Bq m(-3), most of them being less than 100 Bq m(-3). All results were under the International Instances recommended range.

Air Pollutants, Radioactive↗

PubMed2003

Measuring aerosols generated inside armoured vehicles perforated by depleted uranium ammunition.

In response to questions raised after the Gulf War about the health significance of exposure to depleted uranium (DU), the US Department of Defense initiated a study designed to provide an improved scientific basis for assessment of possible health effects on soldiers in vehicles struck by these munitions. As part of this study, a series of DU penetrators were fired at an Abrams tank and a Bradley fighting vehicle, and the aerosols generated by vehicle perforation were collected and characterised. A robust sampling system was designed to collect aerosols in this difficult environment and monitor continuously the sampler flow rates. The aerosol samplers selected for these tests included filter cassettes, cascade impactors, a five-stage cyclone and a moving filter. Sampler redundancy was an integral part of the sampling system to offset losses from fragment damage. Wipe surveys and deposition trays collected removable deposited particulate matter. Interior aerosols were analysed for uranium concentration and particle size distribution as a function of time. They were also analysed for uranium oxide phases, particle morphology and dissolution in vitro. These data, currently under independent peer review, will provide input for future prospective and retrospective dose and health risk assessments of inhaled or ingested DU aerosols. This paper briefly discusses the target vehicles, firing trajectories, aerosol samplers and instrumentation control systems, and the types of analyses conducted on the samples.

Aerosols↗

PubMed1997

Occupational and environmental radiation and cancer.

Epidemiologic evidence on the relation between occupational and environmental radiation and cancer is reviewed. Studies of pioneering radiation workers, underground miners, and radium dial painters revealed excess cancer deaths and contributed to the setting of radiation protection standards and to theories of carcinogenesis. Occupational exposures today are generally much lower than in the past, thus any associated increases in cancer will be difficult to detect. Pooling investigations of these more recently exposed workers, however, has the potential to validate current estimates of risk used in radiation protection. New information on the effects of chronic radiation exposure also may come from studies in the former Soviet Union of Chernobyl clean-up workers and of workers at the Mayak nuclear facilities. Studies of environmental radiation exposures, other than radon, are largely inconclusive, due mainly to the difficulties in detecting the low risks associated with low dose exposures. Thyroid cancer, however, has been linked to environmental radiation from the Chernobyl accident and from nuclear weapons tests. Low-level radiation released during normal operations at nuclear plants has not been found to increase cancer rates in surrounding populations. Radon, a human carcinogen, is the most ubiquitous exposure to human populations; remediating high residential-radon levels is recommended, recognizing that the exposure can never be removed completely because it occurs naturally.

Air Pollutants, Radioactive↗

PubMed2005

Health and environmental impacts of a fertilizer plant--Part II: assessment of radiation exposure.

In the previous paper the authors have studied the radioactive pollution caused by a complex fertilizers production plant. In this paper, the effective doses to the plant workers and to members of the population surrounding the industrial site are estimated. The authors have considered external irradiation, inhalation and ingestion of dust and inhalation of radon and radon daughters as the main occupational exposure routes. After estimating the single contributions, the total effective dose has been calculated as the sum of said contributions. Calculations have been differentiated according to the different tasks of the company employees. The estimated annual effective doses range from 0.6 to 1.4 mSv y(-1). Annual individual effective doses to local residents, resulting from internal and external irradiation caused by particulate matter emitted into the atmosphere by the plant have been estimated. The maximum individual dose rate is estimated to be about 4 microSv y(-1).

Air Pollutants, Radioactive↗

PubMed2006

Towards the use of small amounts of activated charcoal along with well-type NaI(Tl) detector for indoor radon measurements.

The feasibility of using small quantities of activated charcoal and a 7.6 cm x 7.6 cm NaI(Tl) well-type detector was investigated for indoor radon measurements. Vials, filled with 10 g of charcoal, were exposed for different indoor radon concentration levels typical of Kuwait dwellings. After exposure, the vials were sealed and kept for 3 h to allow radon to come into radioactive equilibrium with its progenies and were then analysed by gamma-ray spectrometry using the well-type NaI(Tl) detector. The variation of radon absorption by the vials filled with charcoal with exposure time was also studied. A comparative study of the present technique with the standard technique of using 70 g charcoal canisters and flat NaI detector was also performed. After establishing the suitability of the technique, the charcoal vials were then used to investigate the effect of air-ventilation on the concentration levels of the indoor radon. Results show that there is a reduction in the radon concentration level (up to 25%) when the air-ventilation system was switched on. The paper presents the results of the study on the feasibility of combining small amounts of activated charcoal with a well-type NaI(Tl) detector in the measurement of indoor radon concentrations.

Air Pollutants, Radioactive↗

PubMed2001

[Exhalation of I-131 after radioiodine therapy (RIT): time dependence and chemical form].

AIM: The change of both amount and chemical forms of radioiodine exhaled in the air of rooms with patients on the therapy ward should be investigated depending on radioactivity applied, time after application, and kind of thyroid disease. METHODS: The air of ward-rooms of 62 patients with thyroid carcinoma, Graves' Disease, and autonomy which received different therapy doses, was investigated with an portable constant air flow sampler. Different chemical iodine species (organic, elemental, aerosol bound) were collected during 8 hr in various filters until 3 days after application of the radioiodine capsule, according to their chemical form. The radioactivity in the filters was measured with a well counter on defined time points after application. RESULTS: The radioactivity exhaled was between 0.008 and 0.03% related to activity of radioiodine applied. The percentage of radioiodine exhaled related to the activity applied, differed significantly depending on disease and changed as follows: Grave's Disease > autonomy > carcinoma. The exhalation of radioiodine became stronger with increasing applied activities and showed an exponential decrease with time. The most part of radioiodine was present in organic bound form. This organic portion decreased with time in favour of the other iodine species. CONCLUSION: The degree of accumulation of radioiodine orally applied within thyroid seems to be in direct proportion to the extend of its exhalation. Further measurements directly in the breathing air of RIT-patients are necessary, in order to clarify the relationship between degree of thyroid uptake and quantity as well as chemical form of radioiodine exhaled.

Air Pollutants, Radioactive↗

PubMed2004

Modeling of an industrial environment: external dose calculations based on Monte Carlo simulations of photon transport.

External gamma exposures from radionuclides deposited on surfaces usually result in the major contribution to the total dose to the public living in urban-industrial environments. The aim of the paper is to give an example for a calculation of the collective and averted collective dose due to the contamination and decontamination of deposition surfaces in a complex environment based on the results of Monte Carlo simulations. The shielding effects of the structures in complex and realistic industrial environments (where productive and/or commercial activity is carried out) were computed by the use of Monte Carlo method. Several types of deposition areas (walls, roofs, windows, streets, lawn) were considered. Moreover, this paper gives a summary about the time dependence of the source strengths relative to a reference surface and a short overview about the mechanical and chemical intervention techniques which can be applied in this area. An exposure scenario was designed based on a survey of average German and Hungarian supermarkets. In the first part of the paper the air kermas per photon per unit area due to each specific deposition area contaminated by 137Cs were determined at several arbitrary locations in the whole environment relative to a reference value of 8.39 x 10(-4) pGy per gamma m(-2). The calculations provide the possibility to assess the whole contribution of a specific deposition area to the collective dose, separately. According to the current results, the roof and the paved area contribute the most part (approximately 92%) to the total dose in the first year taking into account the relative contamination of the deposition areas. When integrating over 10 or 50 y, these two surfaces remain the most important contributors as well but the ratio will increasingly be shifted in favor of the roof. The decontamination of the roof and the paved area results in about 80-90% of the total averted collective dose in each calculated time period (1, 10, 50 y).

Adolescent↗

PubMed1997

Radon in residences: influences of geological and housing characteristics.

222Rn is a radioactive gas emitted during the decay of 238U. 222Rn is a recognized lung carcinogen in humans and a common indoor air contaminant. This paper describes the results of research undertaken in 894 residences of the Province of Quebec (Canada), in which one of the objectives was to evaluate the influence of geological and housing characteristics on 222Rn levels. After a random selection of homes, 222Rn concentrations were measured with alpha track detectors in the basement and the main bedroom during two consecutive 6-mo periods. Geological subsoil characteristics were determined from various sources (e.g., geological maps, databanks on uranium sampling in lake and stream sediments), and housing characteristics were documented with a questionnaire. Statistical variance analysis of data indicates that geological factors only explain 5% and 4.5% of the variations in 222Rn concentrations, respectively, in the basement and on the first floor. When variables relative to housing characteristics are added, the analysis explains only 18% and 15% of the variations in 222Rn concentrations in the basement and on the first floor. These results illustrate the difficulties in predicting 222Rn concentrations in homes.

Air Pollutants, Radioactive↗

PubMedDate not supplied

[Importance of studying exposure of the population to radon and its daughters].

INTRODUCTION: Radon and thoron are naturally-occurring radioactive gases, which are products of uranium and thorium decay series, respectively. Uranium and thorium occur widely in the environment, in rocks, soil, air, water, building materials, humans, etc. Radon daughters in the air are predominantly attached to aerosols. A minor part, normally less than 10%, occurs as unattached atoms or ions. The relative distribution of attached daughters in indoor air and equilibrium factor depend on many variables, such as the decay constant, the concentration and size distribution of aerosols and ventilation rates. Increased ventilation decreases the concentration of radon and daughters in the air. OCCURRENCE: Concentration of radon, thoron and their decay products in the air indoors, in mines or houses, is higher than outdoors. In houses, the level of radon daughters may be enhanced by radon from radium rich building materials, landfill, soil and bedrock under the house, radon rich water and by poor ventilation. CONCLUSION: In recent years, several evaluations of human health risks and estimations have been made in regard to the dose-response relationship and lung cancer risk attributable to inhaled radon daughters. Inhalation of radon and thoron daughters leads to deposition in the human respiratory tract and consequent irradiation. Deposition depends on various factors, such as the size distribution of aerosols to which the daughter products of radon are attached, and fraction of unattached daughters. On average, the dose to the basal cell layer in the lung is about 5 to 8 times higher than the dose in the pulmonary region.

Air Pollutants, Radioactive↗

PubMedDate not supplied

[Role of the number of stories in the radiation-sanitary assessment of residential buildings].

Upon long-term exposure, the radioactive gas radon-222 and its decay products in increased doses adversely affect human health. Since the human being spends about 65% of his time in the buildings, it is necessary to evaluate air radiation purity in the rooms, which can be obtained by making a sanitary radiological survey of residential buildings. The scope of the rooms in many-storeyed buildings to be examined can be considerably reduced if the regularities in radon distribution are known. This paper deals with searches for regularities in the distribution of radon levels by the floors of many-storeyed buildings in Tomsk. The room air concentrations of radon were measured for 18 residential buildings with tract detectors upon 1-3--month exposure. The findings showed a different pattern in the distribution of radon levels by the floors in relation to the structural features of a building and to the type of a building material. The wooden and slag-concrete buildings show a 2-3--fold increase in radon levels on the lower floors as compared to the upper ones. A statistical analysis of measurements in the bearing-wall and brick buildings revealed no association of the concentration of radon with the level of a floor, the distribution is near-uniform with 15-30% standard deviation, which is within the limits of measurement error.

Air Pollutants, Radioactive↗

PubMedDate not supplied

[Indoor radon pollution in houses in the Apulian Region of Italy and evaluation of the probability of lung cancer in the population].

BACKGROUND: Radon-222 is a gaseous radioactive chemical which can be transformed into other radioactive chemicals, defined as "products of decay" or "radon's daughter". The modality of radon penetration into the buildings depends on the convection motion created in the ground, which suck it back, so causing the penetration. The principal effect on human health is the increase risk of lung cancer, in proportion to the concentration and the time people spend indoors with exposure to radon. OBJECTIVES: The study proposed to estimate the expected cases of radon-induced lung cancer in the population of Apulia due to contamination by indoor radon. METHODS: The study used the data obtained in a national survey made by ANPA (National Environmental Protection Agency) and ISS (High Health Institute), with the collaboration of the Regional Reference Centres for the Control of Environmental Radioactivity (CRR). In the Apulia Region 310 families (5000 nationwide) were involved, which were selected so as to constitute a representative sample both of the region and the country. Appropriate instruments for the measurement of mean concentrations of indoor radon (passive nuclear trace monitors were installed in the homes of the sample families in two different periods of year). We evaluated the variations of indoor radon concentration in the houses during spring-summer and autumn-winter periods, observing a predictable increase in the latter period. We assessed concentrations in relation to: 1. architectural features and location, 2. construction year, 3. building material, 4. presence of windows. RESULTS: We found higher contamination in the oldest non-cement buildings and on the lower floors. In Lecce and Castrì di Lecce we found a mean radon concentration higher than the national and the regional mean, which is equivalent to annual exposure of 0.54 and 0.46 WLM respectively. For these levels we estimated that the expected cases of radon-induced lung cancer will be 1.5 in Lecce and 1.3 in Castrì per 10,000 inhabitants. CONCLUSION: The results of our investigations confirm that indoor radon pollution is a significant problem as it is one of the main causes of lung cancer. Hence, precautionary measures to reduce as much as possible exposure to indoor radon are highly recommended.

Air Pollutants, Radioactive↗

PubMed2006

A combined analysis of North American case-control studies of residential radon and lung cancer.

Cohort studies have consistently shown underground miners exposed to high levels of radon to be at excess risk of lung cancer, and extrapolations based on those results indicate that residential radon may be responsible for nearly 10-15% of all lung cancer deaths per year in the United States. However, case-control studies of residential radon and lung cancer have provided ambiguous evidence of radon lung cancer risks. Regardless, alpha-particle emissions from the short-lived radioactive radon decay products can damage cellular DNA. The possibility that a demonstrated lung carcinogen may be present in large numbers of homes raises a serious public health concern. Thus, a systematic analysis of pooled data from all North American residential radon studies was undertaken to provide a more direct characterization of the public health risk posed by prolonged radon exposure. To evaluate the risk associated with prolonged residential radon exposure, a combined analysis of the primary data from seven large scale case-control studies of residential radon and lung cancer risk was conducted. The combined data set included a total of 4081 cases and 5281 controls, representing the largest aggregation of data on residential radon and lung cancer conducted to date. Residential radon concentrations were determined primarily by a-track detectors placed in the living areas of homes of the study subjects in order to obtain an integrated 1-yr average radon concentration in indoor air. Conditional likelihood regression was used to estimate the excess risk of lung cancer due to residential radon exposure, with adjustment for attained age, sex, study, smoking factors, residential mobility, and completeness of radon measurements. Although the main analyses were based on the combined data set as a whole, we also considered subsets of the data considered to have more accurate radon dosimetry. This included a subset of the data involving 3662 cases and 4966 controls with a-track radon measurements within the exposure time window (ETW) 5-30 yr prior to the index date considered previously by Krewski et al. (2005). Additional restrictions focused on subjects for which a greater proportion of the ETW was covered by measured rather than imputed radon concentrations, and on subjects who occupied at most two residences. The estimated odds ratio (OR) of lung cancer generally increased with radon concentration. The OR trend was consistent with linearity (p = .10), and the excess OR (EOR) was 0.10 per Bq/m3 with 95% confidence limits (-0.01, 0.26). For the subset of the data considered previously by Krewski et al. (2005), the EOR was 0.11 (0.00, 0.28). Further limiting subjects based on our criteria (residential stability and completeness of radon monitoring) expected to improve radon dosimetry led to increased estimates of the EOR. For example, for subjects who had resided in only one or two houses in the 5-30 ETW and who had a-track radon measurements for at least 20 yr of this 25-yr period, the EOR was 0.18 (0.02, 0.43) per 100 Bq/m3. Both estimates are compatible with the EOR of 0.12 (0.02, 0.25) per 100 Bq/m3 predicted by downward extrapolation of the miner data. Collectively, these results provide direct evidence of an association between residential radon and lung cancer risk, a finding predicted by extrapolation of results from occupational studies of radon-exposed underground miners.

Adult↗

PubMed1998

Some aspects of measurement error in explanatory variables for continuous and binary regression models.

A simple form of measurement error model for explanatory variables is studied incorporating classical and Berkson cases as particular forms, and allowing for either additive or multiplicative errors. The work is motivated by epidemiological problems, and therefore consideration is given not only to continuous response variables but also to logistic regression models. The possibility that different individuals in a study have errors of different types is also considered. The relatively simple estimation procedures proposed for use with cohort data and case-control data are checked by simulation, under the assumption of various error structures. The results show that even in situations where conventional analysis yields slope estimates that are on average attenuated by a factor of approximately 50 per cent, estimates obtained using the proposed amended likelihood functions are within 5 per cent of their true values. The work was carried out to provide a method for the analysis of lung cancer risk following residential radon exposure, but it should be applicable to a wide variety of situations.

Adolescent↗

PubMed1999

Radon-smoking synergy: A population-based behavioral risk reduction approach.

BACKGROUND: Radon and cigarette smoking have a synergistic, multiplicative effect on lung cancer rates. Smokers, and perhaps nonsmoking residents, of smoking households are at increased risk for lung cancer even when radon levels are relatively low. A behavioral risk reduction strategy emphasizing smoking cessation is proposed and data are presented from pilot studies and a short-term evaluation of a randomized intervention trial. METHODS: Pilot studies, including radon testing, interviews, questionnaires, and focus groups, led to a three-arm randomized intervention trial comparing two kinds of written materials and telephone counseling. Smoking households were recruited by offering free radon test kits through an electric utility companies billing system. Three-month follow-up data were obtained by mail and phone. RESULTS: Of an estimated 2,600 smoking households in the utility district, 1,220 requested a radon test kit, and 714 were randomized into three treatment conditions. Brief phone counseling (up to two short calls) significantly increased smoking quit rates, compared to written materials only, and was also related to other risk reduction behaviors (e.g., household ban on smoking). CONCLUSIONS: Offering free radon testing through a public utility billing system is an effective recruitment tool for reaching households at risk due to radon-smoking synergy. Brief telephone counseling is superior to written materials in reducing smoking and encouraging indoor smoking bans. Methods are needed to better inform smokers of their additional risk from exposure to even low levels of radon.

Adult↗

PubMed1994

Radon exposure in residences and lung cancer among women: combined analysis of three studies.

Lung cancer risk in relation to indoor radon was examined in three case-control studies in Stockholm (Sweden), New Jersey (United States), and Shenyang (People's Republic of China). Year-long measurements of radon gas were made in current and past homes of 966 women who developed lung cancer and of 1,158 control women, included in the combined analysis. Nearly 14 percent of the participants were estimated to have a time-weighted, mean, radon concentration in their homes of more than 4 pCi/l (150 Bq/m3) during the period from five to 35 years prior to the date of lung cancer diagnosis (or comparable date for controls). There was a tendency for risk to increase with increasing levels of radon in NJ and Stockholm, but the trends for individual studies and overall were not statistically significant. The estimates of the excess relative risk for indoor exposure per pCi/l were 0.18 (95 percent [CI] = -0.04-0.70) in NJ, 0.06 (CI = -0.05-0.34) in Stockholm, and -0.02 (CI = -infinity-0.03) for Shenyang; these estimates did not differ significantly from each other. The overall excess RR per pCi/l was 0.00 (CI = -0.05-0.07); the confidence limits were sufficiently broad, however, that the overall estimate was still compatible with extrapolations of risks from miners. Cigarette smoking was the predominant cause of lung cancer with the RR significantly elevated in all studies. Within smoking categories, the trend in risk with increasing mean radon concentration was inconsistent. Analyses of data from several studies are complicated by the possibility that there may exist important differences in study bases which might affect results, and which may be controlled only partially through adjustment procedures. Future efforts to combine various residential studies will need to be attentive to the intrinsic limitations of studies to detect low levels of risk as well as the unique uncertainties associated with estimating, accurately, cumulative exposure to indoor radon.

Adult↗

PubMed2005

Radon exhalation rate of some building materials used in Egypt.

Indoor radon has been recognized as one of the health hazards for mankind. Common building materials used for construction of houses, which are considered as one of the major sources of this gas in indoor environment, have been studied for exhalation rate of radon. Non-nuclear industries, such as coal fired power plants or fertilizer production facilities, generate large amounts of waste gypsum as by-products. Compared to other building materials waste gypsum from fertilizer production facilities (phosphogypsum) shows increased rates of radon exhalation. In the present, investigation solid state alpha track detectors, CR-39 plastic detectors, were used to measure the indoor radon concentration and the radon exhalation rates from some building materials used in Egypt. The indoor radon concentration and the radon exhalation rate ranges were found to be 24-55 Bq m(-3 )and 11-223 mBq m(-2) h(-1), respectively. The effective dose equivalent range for the indoor was found 0.6-1.4 mSv y(-1). The equilibrium factor between radon and its daughters increased with the increase of relative humidity.

Air Pollutants, Radioactive↗

PubMed2006

A methodology for assessing the maximum expected radon flux from soils in northern Latium (central Italy).

Northern Latium (Italy) is an area where the Rn risk rate is potentially high because of the extensive outcropping of Neogene U-rich volcanics and the presence of major active tectonic lineaments. The lack of data on Rn risk rates in that area, which is undergoing major urban and industrial development, has prompted this study. It proposes a methodology to evaluate the maximum potential diffusive Rn flux from soils based on the measurement of (226)Ra, (232)Th and (40)K activities by gamma-ray spectrometry, and the measurement of main soil parameters influencing the Rn emanation. This methodology provides a simple, reliable and low-cost tool for drawing up radon flux maps useful to both public planners and private individuals, who want to operate safely in the study area. The proposed methodology may also be applied to other geographic areas outside the prescribed study area.

Air Pollutants, Radioactive↗

PubMed1994

Chromosome aberrations in peripheral lymphocytes from occupants of houses with elevated indoor radon concentrations.

Chromosome analyses were performed in blood lymphocytes of 25 subjects continuously living in houses with indoor radon (222Rn) concentrations exceeding 4-60-fold the German average of 50 Bqm-3. The mean frequency of cells containing dicentrics + ring chromosomes (1.3 +/- 0.3/1000 cells) and the incidence of dicentrics + ring chromosomes per cell (1.5 +/- 0.4 x 10(-3)) were significantly increased compared to the control levels (0.54 +/- 0.11 x 10(-3) for both endpoints). Taking into account the individual radiation history over the last 10 years prior to blood sampling and the life time of peripheral lymphocytes, weighted cumulative radon exposures at the time of blood sampling between 700 and 6300 Bqm-3a were derived. Although individual exposures could not be inferred from the aberration rates, a tendency for an exposure-effect relationship became apparent for two groups of subjects with a mean weighted cumulative radon exposure above and below 1800 Bqm-3a.

Adolescent↗