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At least 1,117 records · Page 62Linked to original sources
PubMed1985

Surveys of natural radiation exposure in UK dwellings with passive and active measurement techniques.

A representative sample of over 2,000 UK dwellings was monitored for a year using thermoluminescent and etchable plastic dosemeters to measure gamma-ray dose rates and radon concentrations. The survey was carried out by post. Each householder completed a questionnaire on the type of dwelling and its characteristics. These data will be used in the assessment of the factors affecting indoor exposure. The mean gamma-ray dose rates were 0.062 and 0.057 microGy h-1 in air and the mean radon concentrations were 25 and 18 Bq m-3 for living areas and bedrooms respectively. Other results of the preliminary data analysis are given. More detailed surveys were conducted in areas where the local geology indicated that elevated exposures to natural radiation might occur. Over 800 dwellings were visited and measurements made of several parameters. The mean gamma-ray dose rates varied from 0.05 to 0.10 microGy h-1 in air. The mean radon concentrations varied from 14 Bq m-3 to 520 Bq m-3. Other findings related to equilibrium factors and regional differences are discussed.

Environmental Exposure↗
PubMed1985

Survey of natural radiation in France.

Survey of natural radiation is conducted in France since 1981, with the assessment of the components resulting from external sources (ground and building materials) using thermoluminescent dosemeters. In addition, the internal exposure to Rn-222 and the potential alpha energy due to radon daughters, are estimated by passive track detectors in the first case and active dosemeters in the second one. This paper presents the French program methods and results with an analysis and discussion of the observed levels.

Environmental Exposure↗
PubMed1985

The reduction of indoor air concentrations of radon daughters without the use of ventilation.

The possibility of using filtration and electric fields both separately and in combination to reduce the indoor air concentrations of radon daughters is described in theoretical terms and with reference to investigations in experimental rooms. For energy conservation considerations these investigations were carried out without reducing the radon concentration by ventilation or other means. The importance of aerosols to the effectiveness of these methods is also described. It is demonstrated that it is possible by use of filtration rates of 3 - 4 times per hour to reduce the potential alpha energy concentration by a factor of 4 - 5. In case of low aerosol concentration the corresponding reduction in lung dose may be much smaller, depending upon the dose-exposure model used, due to the filtration-caused change in the partitioning of the radon daughters between the attached and un-attached states.

Air↗
PubMed1985

Estimation of health effects due to elevated radiation exposure levels in structures.

Uranium mill tailings were used as landfill for many years in the United States before the health risk associated with such use was recognized. Occupants of buildings erected on or adjacent to contaminated landfills may experience radiation exposures sufficient to warrant remedial action. Estimates of the cost-effectiveness of the remedial measures may be provided using a combination of occupancy data, appropriate risk coefficients and projected costs. This effort is in support of decisions by the U.S. Department of Energy (DOE) to conduct remedial action at such locations. The methods used in this project, with examples of their application, will be presented in this paper.

Environmental Exposure↗
PubMed1985

Risk assessment for indoor exposure to radon daughters.

Approaches to and results for the estimation of healths risks from indoor exposure to radon and its daughter products are discussed. Particular weight is given to the derivation of exposure-time-effect relationships using a modified proportional hazard model which has been adapted to account for relevant epidemiological data. The results of this analysis indicate that about (10 +/- 5) % of the lung cancer rate observed in the general public might be correlated to the enhanced exposure to radon daughters in dwellings (at 10 - 20 Bq/m3 (Rn-eq] and in outdoor air. A chronic exposure to indoor Rn-levels at home of about 300 - 500 Bq/m3 (Rn-eq) might possibly double the normal lung cancer rates. The relative fractions of radiogenic lung cancer rates might be nearly the same for smokers and non-smokers, and for men and women.

Climate↗
PubMed1985

Principles of protection against natural radiation.

The recent recommendation for limiting the exposure of the public to natural sources of radiation is one of the more important statements of principle by the International Commission on Radiological Protection in recent years. The evolution of the recommendations is traced, the exposition of the recommendations is reviewed, and the execution of the recommendations is explored.

Costs and Cost Analysis↗
PubMed1985

The effects of human activities on natural radiation exposure: health and regulatory implications.

A decade ago, interest in "enhanced" natural radiation was focused primarily on localized industrial activities, e.g., uranium, radium, thorium and phosphate production. Recognition that all human activities influence natural radiation exposure, and that indoor radon exposure is particularly sensitive to such activities (building construction practices, occupant life-styles) has added a new dimension to the problem. Public health assessments must address the problem of high individual risks of lung cancer as well as substantial population risks that are only minimally ameliorated by reduction of high exposures. In the United States, Federal, State, and local government agencies are collaborating with the private sector in developing the information needed for public guidance. Voluntary standards relating to building construction practices are likely to be developed.

Environmental Exposure↗
PubMed1985

The use of reference levels in the dose limitation procedure.

In this paper the use of reference levels for occupational exposures and for exposures to enhanced natural radiation are compared and related with the annual dose limits. It is concluded that the ICRP recommendations on action levels of indoor exposures to radon and thoron and daughter nuclides suggest a stricter dose limitation for occupational exposures than for exposure of the population to enhanced natural radiation.

Environmental Exposure↗
PubMed1985

Limitation of exposure to natural radioactivity in Canada.

The jurisdictional responsibility for natural radioactivity in Canada is divided between the federal and provincial governments. The desire for uniform standards has resulted in the formation of a scientific group to advise governments concerning the desirability of standards for exposure to natural radioactivity. The various types of exposure are reviewed with emphasis on naturally occurring radon in homes. The scientific Committee could not agree either philosophically or practically on the control level for radon in homes. To resolve this impasse, it undertook a calculation designed to illustrate for Canada, the potential cancers saved each year compared to the actual lung cancer rate, with an estimate of the cost for each limit derived. A second calculation reviewed the cost of modifying the building code and estimated the long term effect by comparing avoided cancers and cost. The calculations are based on cross-Canada surveys, intensive long term investigation of smaller groups of homes and national housing statistics. The results are discussed and serve to illustrate development of the proposed policy.

Canada↗
PubMed1985

The control of indoor radiation exposure.

Surveys of natural radiation indoors permit improved estimates to be made of exposures nationally and of regional variations. In the UK, there are clear indications that individual doses from radon decay products can be more than two orders of magnitude above the national average. A reliable risk factor for lung cancer allows the risks to individuals to be determined, and some members of the public are seen to be exposed to relatively high risks. The feasibility of reducing such risks requires a knowledge of the costs and effectiveness of remedial and preventive measures. There are also social and administrative considerations. The form of standards and the means of implementating them require careful consideration. A systematic approach to these issues is discussed in this paper.

Air↗
PubMed1985

Policy development in The Netherlands concerning enhanced exposure to natural radiation.

Exposure to enhanced natural radiation is treated in terms of the so called "environmental policy life cycle model". The integral policy development is described taking into account environmental, economic and social factors. In the present phase, the policy development is focussed on enhanced levels of radioactivity in building materials. In the following phases, attention will be given to the infiltration of radon from the underground, and to possible enhanced natural radiation due to industrial chemical processes. In each phase the decision process concerning regulations is preceded by a corresponding research programme which forms the necessary scientific basis for the specific regulatory choices. A status report closes the contribution.

Construction Materials↗
PubMed1985

Emissions from unvented kerosene heaters.

Vapor-phase polynuclear aromatic hydrocarbon (PAH) emissions from unvented kerosene heaters were measured. During normal heater operations, tri- and tetra-cyclic PAHs were observed, whereas penta-, hexa- and hepta-cyclic PAHs were not observed. The convective-type heaters had significantly less PAH emissions than the radiant-type heaters. Emissions of particulate soot were also measured. The soot did not contain PAH. A two-compartment model is presented and used to simulate heater operation in a home. Certain simulated PAH levels are similar to that measured in the ambient air of large cities.

Air Pollutants↗
PubMed1986

Organic air pollutants in an aluminum reduction plant.

The content of organic pollutants, other than polycyclic aromatic hydrocarbons (PAH), was determined in air samples collected in the potroom of a Söderberg aluminum reduction plant. The neutral and the basic fractions of the sample extract were analysed, and aza-arenes, carbazoles, 1-nitropyrene and quinones as well as aromatic aldehydes and ketones were identified by gas chromatography and mass spectrometry (GC/MS). Selected compounds were quantified and the results indicate that the concentrations in the potroom atmosphere are high. Some of the identified compounds are known to have adverse health effects, and should therefore be included whenever air quality studies are carried out inside or near aluminum plants.

Air Pollutants, Occupational↗
PubMed1988

Main factors affecting the calculation of radiation dose to the lung from inhalation of radon daughters.

The radiation dose to the lung due to inhalation of radon daughter products has been computed with improved data on lung models, aerosol parameters, deposition and clearance mechanisms. The effects of the following factors on the dose calculated for dwellings have been considered in detail: (a) the diffusion coefficient of the unattached daughter products; (b) the activity median diameter (AMD) of the aerosol size distribution; (c) room ventilation rate; (d) air flow rate in the respiratory tracts; (e) lung morphometry; and (f) effect of phase of the tissue-equivalent medium on the stopping power and range for alpha particles. It has been found that realistic changes in values of some factors change the dose rate by a factor of 2. By adopting likely values, it is calculated that annual dose rates in the fifth bronchial generation are typically 4.3 and 1.8 mGy year-1, at the epithelial surface and 20 microns depth, respectively, for a person exposed to a radon concentration of 23 Bq m-3, the average value for U.K. dwellings.

Aerosols↗
PubMed1988

Polydimethylsiloxanes associated with indoor and outdoor airborne particles.

Electrical contacts are subject to damage by interaction with silicone oils. These oils, which can cause catastrophic failure of electrical contacts, can arise as vapors or aerosols from components of the environment in which the contacts operate. To assess the potential environmental burden of silicones which could be transferred from source to sink (electrical contact), an aerosol sampling methodology was developed which collects silicone-bearing aerosols. These aerosols, collected with impactors and Teflon filters, are then analyzed by a pyrolysis/mass spectrometric method. As little as 0.1 ng of a given viscosity silicone fluid may be detected using this analytical approach. The fingerprint pyrolysis fragments in this study are cyclic dimethylsiloxanes such as hexamethylcyclotrisiloxane (molecular weight = 222), the detection of which is characteristic of polymeric silicone-bearing contaminants in the atmosphere surrounding the silicone-vulnerable electrical contacts.

Air Pollutants↗
PubMed1988

Effects derived from long-term low-level chromium exposure in ferro-alloy metallurgy. Study of absorption and renal function in workers.

Ferro-chromium production is based on the use of chromium oxide (III) and it is generally accepted that chromium in this form is not able to cross biological barriers. However, the data on the toxic and carcinogenic effects of hexavalent chromium in man are now firmly established. Some studies have questioned these data, calling for a clarification as to whether exposure to trivalent chromium can also produce human effects, perhaps with different latency time. A study was carried out on the exposure conditions (type and degree) in a ferro-chromium foundry that had been in operation since 1972. The absorption levels in the working population of the foundry, and the possible toxic effects on the kidney have been investigated. A total of 236 workers (142 employed in production departments, 33 office workers and 61 sub-contractor employees) were examined with measurement of the indicators of dose (urinary-chromium) and of effect on the kidney (albumin, retinol binding protein, and renal tubular epithelium antigens in the urine). Environmental hygiene measurements showed relatively low values of total chromium in the air (always less than 0.160 mg/m3). Hexavalent chromium was absent or, if present, at levels below the sensitivity of the analytical method used (0.001 mg/m3). The values of urinary chromium measured at the beginning and at the end of the working day and at the end of the work shift were always less than 5 micrograms/g creatinine, which has been proposed as a biological limit in chromium exposure. However, differences were observed between groups of subjects employed on different jobs, which is indicative of an absorption process varying according to the degree of exposure. The indicators of effect did not reveal any renal impairment, even early, that could be attributed to the toxic action of chromium.

Adult↗
PubMed1988

Element concentrations in the air of an indoor shooting range.

Elemental emissions during firing in a shooting range were measured for different types of ammunition. When using Hirtenberger bullets, lead, barium, antimony and to a lesser extent copper and arsenic were the primary metal pollutants. Stationary sampling at three locations in the range did not reveal large concentration gradients. Large concentration variations were observed by sampling before, during and after shooting. Lead and antimony concentrations peak at 5060 and 119 micrograms m-3, respectively. Soil elements such as aluminium, sodium and calcium are enriched during shooting, probably due to soil resuspension by the shooters and the bullets hitting the sand backstop. After shooting has ceased the concentrations fall to within pre-shooting levels within a couple of hours. Measurement of the aerodynamic particle size shows low mass median diameters for the elements emitted during firing and larger diameters for the soil-associated elements. The peak airborne concentrations measured by stationary sampling, and human exposure measured by a personal sampler carried by an instructor were compared with threshold limit values. During the shooting the TLV is significantly exceeded for lead.

Air↗