Radon exposure

Care must be taken in handling radon, as with other radioactive materials. The main hazard is from inhalation of the element and its solid daughters which are collected on dust in the air. Good ventilation should be provided where radium, thorium, or actinium is stored to prevent build-up of the element. Radon build-up is a health consideration in uranium mines. Recently radon build-up in homes has been a concern. Many deaths from lung cancer are caused by radon exposure. In the U.S. it is recommended that remedial action be taken if the air in homes exceeds 4 pCi/1. 

Effects of indoor air pollutants on humans are essentially the same as those described in Chapter 7. However, there can be some additional pollutant exposures in the indoor environment that are not common in the ambient setting. From the listing in Table 23-1, radon exposures indoors present a radiation hazard for the development of lung cancer. Environmental tobacco smoke has been found to cause lung cancer and other respiratory diseases. Biological agents such as molds and other toxins may be a more likely exposure hazard indoors than outside. 

Siniscalchi, M.S., Rothney, L.M., Toal, B.F., Thomas, M.A., Brown, D.R., van der Werff, M.C., and Dupuy, C.J., Radon exposure in Connecticut Analysis of three statewide surveys of nearly one percent of single family homes, in The 1990 International Symposium on Radon and Radon Reduction Technology, Atlanta, GA, February 1990. 

Reubel, B., C. Atzmuller, F. Steinhausler, and W. Huber, Biophysical Effects on Human Lung Cells Due to Radon Exposure, this volume (1987). 

On the basis of a conversion coefficient of 5.5 mSv WLM"1, occupants of the vast majority of dwellings in the UK receive annual effective dose equivalents less than 2 mSv. Even in the areas surveyed because of their potential for high radon exposures, the annual effective dose equivalents are unlikely to exceed a few tens of mSv. However, in certain areas of Cornwall and Devon, annual effective dose equivalents higher than 25 mSv may be received in a small percentage of dwellings. In some dwellings more than 50 mSv per year may be received. 

In the radon surveys the primary quantity determined is the indoor air mean radon activity concentration. From a radiological health perspective it is the dose arising from the inhalation of radon daughters that is of interest. The conversion from radon exposure to annualised effective dose equivalent for the survey was carried out using the factors given in Table I which are similar to those being used in other European surveys. The occupancy and equilibrium factors given in this table are assumed mean values for Irish... 

Some of the 220 detectors recently recovered have been analysed not only for radon exposure but also to determine the value of F (the equilibrium factor) in the houses. A preliminary set of such F factor results, obtained by analysing the inner and outer LR- 115 track densities of each detector, are presented in Table III for 12 houses with mean indoor radon concentrations greater than 200 Bq/nP. In Table III are also presented radon daughter doses estimated using the individually determined equilibrium factor values F together with the doses estimated on the basis of an assumed mean F factor value of 0.45. 

Steinhausler,F. and E. Pohl, Lung Cancer Risk for Miners and Atomic Bomb Survivors and its Relevance to Indoor Radon Exposure, Radiation Protection Dosimetry Vol.7, No.1-4 389-394 (1983). 

There is little indication here of any correlation between radon exposure and educational level. 

Problems in Inferring Past Radon Exposure from Present Measurements... 

Any study of lung cancer-radon exposure correlations, including both case-control studies and the one considered here, must infer radon exposures many decades ago from measurements made at present. 

Some of the data presented above indicate that average radon levels are now only half as large in summer as in winter. Thus the summer air conditioning season contributes only 10-15% of our annual radon exposure, and the correction due to this factor is less than 10%. 

Investigations with Animals. A further support of the hypothesis described above can be found in investigations carried out with animals Leonard et al. (1979) found in an area with high natural radioactivity in France a small but significant increase of chromosome aberrations in the lymphocytes of rabbits. The rabbits were kept in a hut for 12 months, and received up to 0.7 Gy/year from gamma rays together with more than 6 Gy alpha doses from radon and daugthers. Further experiments with rabbits at radon exposure under controlled conditions have shown that the chromosome... 

Biophysical Effects of Radon Exposure on Human Lung Cells... 

Cross, ET. 1990. Health effects and risks of radon exposure. Pages 223-237 in S.K. Majumdar, R.F. Schmalz, and E.W. Miller (eds.). Environmental Radon Occurrence, Control and Health Hazards. Pennsyl. Acad. Science, Easton, PA. 

Underground hematite mining, when radon exposure exists... 

Radon is another example of a very curious and toxic compound that many of us regularly inhale, hopefully in small amounts. For those regularly exposed to radon, there is an increased risk for lung cancer and, for those that smoke, radon exposure results in a three-fold increase in the incidence of lung cancer. In the United States it is estimated that indoor radon exposure causes between 7000 and 30,000 lung cancer-related deaths each year, second only to tobacco smoking. Radon-222 is a colorless and odorless radioactive gas that results from the decay of radium-226, which is widely distributed in the earth s crust. Radon decays with a half-life of 3.8 days into solid particles of polonium. It is actually the breakdown of... 

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