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At least 19 recordsLinked to original sources
PubMed1989

Lung cancer mortality among nonsmoking uranium miners exposed to radon daughters.

Radon daughters, both in the workplace and in the household, are a continuing cause for concern because of the well-documented association between exposure to radon daughters and lung cancer. To estimate the risk of lung cancer mortality among nonsmokers exposed to varying levels of radon daughters, 516 white men who never smoked cigarettes, pipes, or cigars were selected from the US Public Health Service cohort of Colorado Plateau uranium miners and followed up from 1950 through 1984. Age-specific mortality rates for nonsmokers from a study of US veterans were used for comparison. Fourteen deaths from lung cancer were observed among the nonsmoking miners, while 1.1 deaths were expected, yielding a standardized mortality ratio of 12.7 with 95% confidence limits of 8.0 and 20.1. These results confirm that exposure to radon daughters in the absence of cigarette smoking is a potent carcinogen that should be strictly controlled.

Adult↗
PubMed1984

Lung cancer in Swedish iron miners exposed to low doses of radon daughters.

In a retrospective study, we investigated lung-cancer mortality from 1951 to 1976 in 1415 Swedish iron miners exposed to short-lived radioactive daughters of radon gas at concentrations leading to annual doses close to the currently accepted occupational limit. Fifty deaths from lung cancer were observed, as compared with 12.8 expected; expected rates were determined by a smoking-specific analysis based on data from a random sample of the Swedish male population. Among nonsmokers 18 deaths were observed, as compared with 1.8 expected; among current smokers and recent exsmokers 32 deaths were observed and 11.0 were expected. The effects of smoking and exposure to alpha radiation from radon daughters were nearly additive. Comparison of lung-cancer risk coefficients from this study and from other cohort studies of underground miners showed good agreement. Exposure to radon daughters is a major medical problem is underground metal mining, but our results also indicate that exposure to radon daughters at home accounts for an appreciable number of cases of lung cancer in the general population.

Adult↗
PubMedDate not supplied

Contamination of individuals by radon daughters: a preliminary study.

Body radon daughter contamination reflects relative individual respiratory exposures to radon daughters; counts can be related both to household radon levels and to lung cancer risk factors such as sex and tobacco smoking. Radon daughters were counted by gamma spectroscopy from 180 adult residents of eastern Pennsylvania. A seven-position, 35-min scan was conducted in a mobile body counter, generally during afternoon or evening hours. Track-etch detectors for household radon were distributed, and were recovered from 80% of the subjects. Over 75% of the population had environmentally enhanced radon daughter contamination. House radon levels were strongly related, as anticipated, to radon daughter contamination in the 112 subjects for whom both sets of measurements were available (p less than .001); basement measurements were as strongly related to personal contamination as were living area measurements; bedroom measurements were slightly more strongly correlated. Both sex (p less than .02) and cigarette smoking (p less than .01) significantly modified the relationships, after nonlinear adjustment for travel times. Using a logarithmic model, a given house living-area radon level was associated in females with body contamination by radon daughters 2-3 times that in males. Nonsmokers had 2-4 times higher levels of contamination than smokers. Results are for the total of internal and external contamination, these being highly correlated in preliminary experiments. Time usage and activity patterns of the subjects are believed to be important in explaining these findings, and may become important variables in radon risk assessment.

Adult↗
PubMed1983

Experiences and concerns on lung cancer and radon daughter exposure in mines and dwellings in Sweden.

A high mortality from lung cancer among miners was reported from Central Europe already in the 19th century. In the 60s and 70s several reports have indicated an increased lung cancer mortality among uranium miners and other metal-miners, e.g. in the US, UK, France and Sweden, but also among fluorspar miners in Canada. The cause is supposed to be the decay products of radon as emanating from the rocks, i.e. the alpha-radiation from short-lived radon daughters. Radon and radon daughter exposure in dwellings have more recently attracted interest as a potential hazard to the general population, especially since radon daughter concentrations seem to have increased due to more effective insulation for energy saving. In many Swedish houses the radon daughter exposures amount to levels similar to that of mines. Some epidemiological evaluations of the relationship between lung cancer and exposure to radon daughters, i.e. residency in stone houses versus wooden houses (with and without consideration of the contribution of radon from the ground underneath the houses), seem to indicate a risk also to the general population and, moreover, the risk of smoking seems to be several times greater in stone houses than in wooden houses, the latter usually having less radon daughters on the average.

Adult↗
PubMed1984

Time variation of radon daughters concentration in snowfall.

Time variation of radon daughters concentration in snowfall was measured continuously. The relations of radon daughters concentration in snowfall to the precipitation and to atmospheric radon daughters concentration were investigated. It has become clear that when precipitation is small, radon daughters concentration in snowfall is distributed in a wide range, and that the quantity of radon daughters brought to ground surface by snowfall is proportional to precipitation. Washout effect of the snowfall on atmospheric radon daughters was also investigated.

Atmosphere↗
PubMed1993

The biological effectiveness of radon daughter alpha particles. I. Radon, cigarette smoke and oncogenic transformation.

Epidemiological data from uranium miners have not been able to provide a definitive model depicting the interaction between radiation exposure and smoking in the etiology of lung cancers among miners who also smoke. Using the well-characterized C3H 10T1/2 cell system, the toxicity and oncogenic transforming incidence by either gamma-rays or He4 ions, with or without concurrent exposure to cigarette smoke condensate (CSC), were examined. He4 ions had the same energy spectrum as radon. CSC, extracted from 2R1 cigarettes, induced a dose-dependent toxicity and oncogenic transformation incidence in 10T1/2 cells. CSC, in combination with a 2 Gy dose of gamma-rays, induced a toxicity and transforming response that was largely additive in nature. Similar additive modes of interaction were also observed when CSC was combined with He4 ions at a dose that was equivalent in cell killing to that used for gamma-rays. These results provide evidence that radiation and smoking have an additive effect in oncogenic transforming potential and may provide an experimental handle towards an epidemiological uncertainty.

3T3 Cells↗
PubMed1975

Size distribution of radon daughter particles in uranium mine atmospheres.

The size distribution of radon daughters was measured in several uranium mines using four compact diffusion batteries and a round jet cascade impactor. Simultaneously, measurements were made of uncombined fractions of radon daughters, radon concentration, working level and particle concentration. The size distributions found for radon daughters were log normal. The activity median diameters ranged from 0.09 mum to 0.3 mum with a mean value of 0.17 mum. Geometric standard deviations were in the range from 1.3 to 4 with a mean value of 2.7. Uncombined fractions expressed in accordance with the ICRP definition ranged from 0.004 to 0.16 with a mean value of 0.04. The radon daughter sizes in these mines are greater than the sizes assumed by various authors in calculating respiratory tract dose. The disparity may reflect the widening use of diesel-powered equipment in large uranium mines.

Aerosols↗
PubMed1985

Radon and radon daughter levels in energy efficient housing.

Radon and radon daughter concentrations have been measured in 33 "energy-efficient" homes in a small subdivision in Kanata, Ontario. Integrated radon measurements were determined over three month periods for a year using solid state nuclear track detectors. Radon and radon daughter grab sample determinations were made during corresponding periods and confirm the distributions of the integrated radon measurements. Annual average individual home radon concentrations show an 8 fold concentration range between homes. This variability in radon concentrations is not reflected in the range of air exchange rates for the homes. A distinct seasonal variation is noted for the median values of the radon and radon daughter concentrations and the equilibrium factor F in the dwellings.

Energy-Generating Resources↗
PubMed1989

Lung carcinomas in Sprague-Dawley rats after exposure to low doses of radon daughters, fission neutrons, or gamma rays.

The effectiveness of radon-daughter inhalation and irradiation with fission neutrons and gamma rays in the induction of lung carcinomas in Sprague-Dawley rats at low doses is compared. Earlier reports which compared radon-daughter inhalations and neutron irradiations over a wider range of doses were based on dosimetry for the radon-daughter inhalations which has recently been found to be faulty. In the present analysis, low-dose experiments were designed to derive revised equivalence ratios between radon-daughter exposures, and fission neutron or gamma irradiations. The equivalence is approximately 15 working level months (WLM) of radon daughters to 10 mGy of neutrons (the earlier value was 30 WLM to 10 mGy). The relative biological effectiveness (RBE) of neutrons is 50 or more at a gamma-ray dose of 1 Gy. In these experiments with low doses and exposures, the lifetime incidences can be estimated from the raw incidences, while the derivation of the time dependence of the prevalence is essential for the estimation of RBE values and equivalence ratios.

Administration, Inhalation↗
PubMed1986

Contribution of radon and radon daughters to respiratory cancer.

This article reviews studies on the contribution of radon and radon daughters to respiratory cancer and proposes recommendations for further research, particularly a national radon survey. The steady-state outdoor radon concentration averages 200 pCi/m3, and indoor levels are about 4 times higher. The primary source of radon in homes is the underlying soil; entry depends on multiple variables and reduced ventilation for energy conservation increases indoor radon levels. Occupational exposures are expressed in units of radon daughter potential energy concentration or working level (WL). Cumulative exposure is the product of the working level and the time exposed. The unit for cumulative exposure is the working level month (WLM). The occupational standard for radon exposure is 4 WLM/year, and 2 WLM/year has been suggested as a guideline for remedial action in homes. Epidemiologic studies show that miners with cumulative radon daughter exposures somewhat below 100 WLM have excess lung cancer mortality. Some 3% to 8% of miners studied have developed lung cancer attributable to radon daughters. All of the underground mining studies show an increased risk of lung cancer with radon daughter exposure. All cell types of lung cancer increased with radon exposure. If radon and smoking act in a multiplicative manner, then the risk for smokers could be 10 times that for nonsmokers. The potential risk of lung cancer appears to be between 1 and 2 per 10,000/WLM, which yields a significant number of lung cancers as some 220 million persons in the United States are exposed on average to 10 to 20 WLM/lifetime.

Carcinoma, Bronchogenic↗
PubMed1992

Measurements of the efficiency of respirator filters and filtering facepieces against radon daughter aerosols.

The filtration efficiencies of respirator filters and filtering facepieces have been tested against radon daughters in a fluorspar mine. The test method involved the use of sampling filters exposed to natural radon daughters in air filtered by the test respirators. Respirators with a filtration efficiency high enough for them to be considered suitable for use against toxic dusts generally reduced radon daughter levels by 90% or more, though nuisance dust masks were ineffective. The measured penetration of radon daughters through the former types of filter correlated reasonably well with the penetration of 0.1 microns neutralized monodisperse aerosols, and with that of the BS 4400 sodium chloride aerosol, measured in the laboratory. To simulate exposure in working conditions mine air containing radon daughters was drawn through the test filters for 8 h, but their performance was not affected and they were not measurably radioactive as a result.

Aerosols↗
PubMed1983

Radon daughter plateout--I. Measurements.

Radon daughter plateout (surface deposition) was measured directly in 1.9 and 20-m3 chambers. To test the effect of different parameters on plateout, measurements were made over a wide range of particle concentrations and sizes. The results indicate that plateout is strongly dependent on particle concentration. The ratio of surface-deposited activity to total daughter activity in the chamber varied from 4% at particle concentrations greater than 10(5)/cm3 to 86% for particle concentrations less than 10(3)/cm3. Comparison for the experimental data with a theoretical model shows that the theory overestimates plateout and underestimates the airborne concentration by factors of about 3.5 and 3.3, respectively.

Aerosols↗
PubMed1996

Enhanced deposition of radon daughter nuclei in the vicinity of power frequency electromagnetic fields.

We report the attraction of radon daughter nuclei in normal domestic room air to everyday sources of power frequency electromagnetic fields. TASTRAK plastic track detectors were used to measure alpha-emission from the radon (222Rn) daughters 218Po and 214Po close to 50-Hz mains frequency power cables and domestic appliance leads. We observed that wires carrying mains frequency potential attract radon daughter nuclei in a manner visually similar to the attraction of iron filings to a magnet. Increased deposition of up to a factor of 18 was observed. Further experiments designed to simulate the effect of overhead power lines at ground level showed large scale variations in local plateout and airborne concentration of radon daughters. The effects appear to be due to interactions of the electric component of the EM-field with both the ultrafine and attached fraction of radon daughter aerosols. Three mechanisms have been examined. First, aerosols instantaneously polarize in sympathy with the electric component of an applied mains frequency EM-field and as a result may migrate up strong E-field gradients. This effect is however quite weak and may only affect larger aerosols in strong field gradients. Second, charged aerosols oscillate in a 50-Hz field and in the case of the ultrafine fraction this may lead to significantly increased plateout. Third, there is the possibility that oscillation of charged aerosols induces fluctuations in the magnitude of the instantaneous charges carried and this results in a diffusive-like motion along the field lines. The effect on dose to body organs is considered. Enhanced plateout on the skin is likely, increasing the dose to the basal layer. The dose to internal organs is governed initially by inhalation and lung deposition of radon daughters. Therefore increased local concentration in room air could lead to increased dose by inhalation. E-fields are heavily attenuated by the human body and body values in tissue of no more than 10(-4) of the external field strength have been suggested. Nevertheless calculations suggest that under exposure to strong external fields this may still be sufficient to alter the deposition pattern of the charged component of the ultrafine fraction in the bronchial region. In contrast it is unlikely that internal electric fields could significantly affect the attached radon daughters. In this context the lack of measurements of residual E-fields in the cavities of the mouth, pharyngeal and bronchial regions is of considerable importance and should be addressed. We believe that the observations may have implications for the apparent enigma that there is no persuasive biological evidence to show that power frequency electromagnetic fields can influence any of the accepted stages in carcinogenesis. On the contrary, the observations show that EM-fields can concentrate in their vicinity a cocktail of radon daughter nuclei, a known carcinogen, and presumably other potentially harmful agents.

Aerosols↗
PubMed1998

Gamma-spectroscopy investigation of radon daughter deposition on electrostatically charged surfaces.

The effect of static electricity on the deposition of radon daughters onto charged surfaces is determined by a combined experimental and theoretical analysis. Experiments with charged surfaces exposed to the air in a normal working environment are analysed to determine an empirical radon daughter deposition rate. This factor is utilized to estimate the daughter deposition on a human head which is exposed to similar conditions of air quality and static charging. The results indicate that typical levels of static electricity can enhance the deposition of radon daughters by orders of magnitude compared with the uncharged condition. The corresponding yearly alpha dose equivalents to the basal skin layer and to the eye exceed recommended limits. Beside having an important impact from the public health perspective, these results suggest that the obscure and contradictory correlations found between radon concentrations and adverse health effects may arise from a failure to account for the effects of static electricity.

Air Pollutants, Radioactive↗
PubMed1984

Electrets for passive radon daughter dosimetry.

Electrets are demonstrated to collect radon-daughter aerosols with efficiencies which are similar to the efficiencies of aluminum discs held at a potential equal to the surface potential of the electrets. The properties of the electrets are suitable for incorporation of an electret into a radon-daughter dosimeter as the passive collecting element.

Aerosols↗
PubMed2002

Application of pylon radon daughter standard for calibration of radiometers.

Radiometers for measurements of radon daughter potential energy used in the surveillance of the work environment need a systematic calibration. This paper presents how a commercially available device produced by the Pylon Company can be applied. This device allows to produce, simply and directly, standard sources of radon daughters, corresponding with the energy, geometry and properties of radiation originated from an air sample. The calibration yielded the results that proved to be in agreement with those obtained previously by means of radon chamber.

Calibration↗
PubMed1989

Measurement of atmospheric radon daughter concentrations at the campus of Fukushima Medical College.

Radon daughter concentrations in outdoor and indoor air were measured at the campus of Fukushima Medical College. Radon daughters in the air were sampled with a flow rate of 20 L/min through a glass fiber filter or a membrane filter, and the decay of activity on the filter was analyzed with two types of technique, i.e., the gross-beta one-count method using a G.M. tube and the alpha spectroscopic method using a semiconductor detector. The present paper describes principles and techniques of the measurement in detail.

Air Pollutants↗