Lung cancer radon

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. 

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. 

No immediate symptoms but estimated to contribute to between 7,000 and 30,000 lung cancer deaths each year. Smokers are at higher risk of developing radon-induced lung cancer. 

The known health effect associated with exposure to elevated levels of radon above the action or guidance level is an increased risk of developing lung cancer. The guideline levels for radon in existing homes are as follows ... 

The array of proposed standards differ in details, but the approaches are the same in two important ways (a) no account is taken of possible technological or medical advances during the next millennia (b) the level of harm to be avoided in the distant future is miniscule compared to the level of harm that society accepts with a shrug today - for example, the dose of about 2 mSv per year that the average person in the US. now receives from indoor radon, with projected lung cancer fatalities in excess of 15,000 per year. 

Steinhausler (1987) and Martell (1987) review the dosimetric models and related model studies. Their view is that there are still very large uncertainties in the existing data and in the extrapolation from the exposure and response data for underground miners and experimental animals to the health effects of the radon progeny levels to which the general public is exposed. B.L. Cohen (1987) describes his work to relate radon measurements with lung cancer rates for various geographical areas to test the concept of a dose threshold. 

Steinhausler, F., On the Validity of Risk Assessments for Radon Daughters Induced Lung Cancer, this volume (1987). 

Harley, N.H., Radon and Lung Cancer in Mines and Homes, New England Journal of Medicine, 310 1525-1526 (1984). 

Sevc J., Kunz E. and Placek V., 1976, Lung Cancer in Uranium Miners and Long-Term Exposure to Radon Daughter Products, Health Phys.,... 

Hofmann, W., Cellular Lung Dosimetry for Inhaled Radon Decay Products as a Base for Radiation - Induced Lung Cancer Risk Assessment. Radiat. Environ. Biophys. 20 95-112 (1982). 

Radon (Rn-222) daughter exposure at home is a potentially significant contributor to background lung cancer rates. In western countries, an increase in the number of energy-efficient homes threatens to increase the exposure of the occupants to radon and its decay products by reducing ventilation rates. This is also true in Japan, especially in winter. Japan is situated in the temperate zone, which results in a rather long hot and humid summer climate. Consequently,... 

The risk of lung cancer from exposure to radon daughters in homes is derived by assessing lung dose, either absolutely by evaluating an effective dose equivalent (UNSCEAR, 1982 NEA, 1983) or by scaling the... 

The histological types of lung cancer seen to excess in uranium miners reflect those in the population at large (Masse, 1984). These occur almost entirely in bronchial airways. Approximately 207 are adenocarcinomas which occur in peripheral bronchioles (Spencer, 1977) where there are no basal cells. Squamous cell cancers predominate in miners exposed early in life to relatively low concentrations of radon daughters (Saccomanno et aJL., 1982). These are considered likely to arise from the secretory small mucous granular cells which undergo cell division and extend to the epithelial surface (Masse, personal communication). Division of these cells is accelerated after irritation by toxicants such as cigarette smoke or infectious diseases (Trump et a L., 1978). 

The lung cancer risk from radon daughter exposure is known only for occupationally exposed males. In order to determine the risk in environmental situations it is necessary to determine whether the bronchial alpha dose, which confers the risk, is similar to that in mines. 

The normal or average risk from whole body gamma-ray exposure in the environment is only about 10% of that from average radon daughter exposure and much less in elevated indoor environments. Considering that the radon daughter lung cancer risk can be derived directly from exposure in most cases, effective dose equivalent is an unnecessary step. 

The Validity of Risk Assessments for Lung Cancer Induced by Radon Daughters... 

Edling,C., Lung Cancer and Radon Daughter Exposure in Mines and Dwellings study no. V. Linkoping University, Medical Dissertation No. 157, Dept, of Occup. Med., Linkoping, Sweden (1983). 

Radford,E.P., and K.G. St.Clair Renard, Lung Cancer in Swedish Iron Miners Exposed to Low Doses of Radon Daughters, The New England Journal of Medicine, 310 1485 (1984). 

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). 

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