Estimating Indoor Radon Exposure

Application of Uncertainty Analysis to Ecological Risk of Pesticides 

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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... 

It should be noted that there is intense controversy as to the health effects of radiation doses below about 100 mSv per year. This estimate of 15,000 annual cancer deaths from indoor radon, as well as estimates of tens of thousands of eventual cancer deaths from Chernobyl exposures, is obtained by applying the linearity hypothesis. This hypothesis has been adopted by most regulatory agencies but is strongly contested by some scientists who believe it overestimates the effects of radiation at low dose levels. Of course, if calculations based on this hypothesis overestimate the deaths from indoor radon, they also overestimate the effects of potential radiation from a waste repository. 

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. 

Radon is a carcinogen present in indoor air that is estimated by some studies to be responsible for about 1% of all lung cancers. 40 41 Other studies, however, question whether it is radon alone or radon in combination with cigarette smoke exposure that is responsible for the cancers. Even those studies that question the effect of radon exposure as a cause of... 

Abstract— The aim of this study is to estimate risks of inhalation dose (543 26.87B/m of indoor radon gas on a lung cancer for the exposed Rabbits by using a histological method. For this purpose, new exposure technique equipped with the nuclear track detectors type CR-39 (CR-39NTDs) has been designed to expose the Rabbits for 90 days. To get an optimum time of exposure the make damage on the lugs, it has been classified into three times 30,60 and 90 days. 

For exposure indoors of the general population, it is more useful to work in terms of the concentration of radon than the concentration of decay products. Brown et al. (1986) found the average concentration of 222Rn in Cornish houses to be 300 Bq m-3, and Nero (1988) has estimated that 2% of homes in the USA have similar or higher concentrations. Assuming an annual effective dose equivalent of 80//Sv... 

The occupational, accidental, and wartime experiences have provided the basis for the estimation of risk to humans following radiation exposure. However, cosmic, cosmo-genic, inhaled, and in-body radiation deliver total body effective doses of 3 becquerel per year total effective dose. The average radon concentration indoors is 40 becquerel... 

Lubin JH, Boice JD Jr., Edling C, et al. 1995. Lung cancer in radon-exposed miners and estimation of risk from indoor exposure. Journal of the National Cancer Institute 87(11) 817-27. 

The studies just cited address the risk of developing lung cancer following exposure to radon, asbestos, and tobacco. Though estimating these risks are complicated by human exposures to other environmental pollutants, both indoors and outdoors, I42 44 these and other similar studies do definitively establish the enhanced effects of exposure to mixtures on the development of lung cancer and other cancers. This subject is discussed further in Chapter 21. 

Substances that are chemically unreactive are generally not thought to be dangerous to one s health. However, radon, a colorless, odorless, chemically inert noble gas, is considered to be a serious health risk because it is radioactive. It is believed to be the leading cause of lung cancer among nonsmokers. It has been estimated by U.S. officials that up to 8% of the annual lung cancer deaths in the United States can be attributed to indoor exposure to radon-222. 

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