149 8 Radiation from the Gods The U.S. Environmental Protection Agency (EPA) considers indoor radon to be one of the most important causes of cancer in the U.S. 1 The agency estimates that about 20,000 lung cancer deaths annually are caused by radon exposure in homes. 2 Only cigarette smoking (responsible for about 150,000 lung cancer deaths annually) causes more lung cancer deaths. If the EPA is right, the risk of radon exposure could far exceed hazards associated with typical pollutants in outdoor air, drinking water, and certain foods and would approximate hazards of some more common activities such as automobile travel. 3 Because the entire U.S. population is exposed, radon gas would account for more deaths than almost any other agent the EPA regulates. Lung cancer and domestic radon exposure provide a clear example of many of the themes and issues discussed in this book. Federal and state governments have aggressively promoted indoor radon as a serious public health hazard because radon is a major contributor to radiation dose, and we have the technological capabilities to do something about high radon levels in houses and buildings. Much of the debate on the public health consequences of radiation exposure centers on the question of uncer- tainty in risks at small radon levels. Because of the limited data that shows significant risks from epidemiological studies of indoor radon, linear no-threshold theory (LNT) is used to predict risks based on observations made in the occupational (mining) environment where radon levels are thousands of times higher. Communicating radon risks has proven to be a challenging exercise because of the significant public apathy toward radon remediation. Using comparisons of lung cancer deaths from radon and cigarette smoking has proven to be a less than satisfactory communication strategy, in part because smoking and radon exposure are unrelated activities. Public health impacts of radon exposure in homes are not clearly established because risks are highly uncertain. For more than 95% of U.S. homes, risks are either too small to be measured reliably or are essentially zero. The residential radon problem is a clear example of the need to adopt a dose-based system of protection whereby radon levels in homes are compared to natural background levels as a basis for public policy and decision making. A dose-based system avoids the need to quantify risks that are highly uncer- tain. Except for homes that have very high radon levels, decisions to remediate based on risk are highly questionable. Finally, managing radon risks and costs of home remediation highlight the important problem of allocating limited economic resources to manage a public health problem (lung cancer) that has other more significant roots. Radon is the single largest source of human exposure to ionizing radiation background radiation and represents about 40% of the exposure from all sources including medical uses. 4 7977_C008.fm Page 149 Thursday, September 14, 2006 2:44 PM © 2007 by Taylor & Francis Group, LLC (Table 8.1). It accounts for about half of the total average annual dose from natural 150 Radiation Risks in Perspective Doses from medical applications of radiation and from radon have particularly wide ranges. Medical doses depend on the size of the patient and the nature of the diagnostic study. Simple chest x-rays result in doses approximating 0.5 mSv; com- puterized tomography (CT) studies (particularly in children) and fluoroscopic exam- inations may deliver doses of several tens of mSv. Factors contributing to variations in radon levels are related to local geological and housing characteristics. The EPA’s estimate of 20,000 lung cancer deaths annually from domestic exposure to radon comes from extrapolating risks derived from statistically significant data from occupational exposures in uranium and other metal mining environments. Miner stud- ies have clearly established radon gas as a cause of lung cancer, although uncoupling radiogenic risk from smoking risk has been problematic since many miners smoked. The interaction of risks from cigarette smoking and radon exposure appears to be more than additive, but the exact nature of the interaction remains unclear. Demonstrating that lung cancer risk is elevated due to domestic radon has proven to be enormously difficult because radon levels are thousands of time lower than in the mining environ- ment. Communicating radon risks has also been challenging because of public apathy. Radon as a domestic health issue is a relatively new concern. For several decades radon gas has been a known cause of lung cancer. However, the hazard was believed to be restricted to underground mining settings where very high concentrations could accumulate. Radon gas is measurable in homes, but governments and technical experts never realized that high concentrations similar to that found in mines could accumulate in homes. The saga of Stanley Watras and his home in Pennsylvania changed all that. THE WATRAS CASE Stanley Watras lived near Harrisburg, PA, and worked as an engineer at the nearby Limerick Nuclear Power Plant. 5 When exit radiation portal monitors were installed at the plant, Watras continuously tripped the exit portal radiation monitor on his way to off-site meetings and at the end of his shift. What made this troublesome was the fact that Limerick was not yet operational. Furthermore, analysis of the radioactive TABLE 8.1 Sources of Radiation Exposure Source Average Annual Effective Dose (mSv) Cosmic rays 0.4 (range: 0.3–1.0) External terrestrial radiation 0.5 (range: 0.3–0.6) Inhalation (mainly radon gas) 1.2 (range: 0.2–10.0) Ingestion 0.3 (range: 0.2–0.8) Medical diagnostic 0.5 (range: 0.1–25.0) Sources: National Council on Radiation Protection and Measurements, Exposure of the U.S. Population from Diagnostic Medical Radiation , NCRP Report No. 100, NCRP, Bethesda, MD, 1989; United Nations Scientific Committee on the Effects of Atomic Radiation, UNSCEAR 2000 Report to the General Assembly, with Scientific Annexes, Volume I: Sources , United Nations, New York, 2000. 7977_C008.fm Page 150 Thursday, September 14, 2006 2:44 PM © 2007 by Taylor & Francis Group, LLC Radiation from the Gods 151 contamination indicated the presence of radon gas and its decay products in con- centrations that could not be accounted for on-site. On December 17 or 18, 1984, in an attempt to further investigate the problem, Watras decided to enter through the exit portal monitor on his way into work and again set the monitors off. At this point, Watras asked plant management to sample his house since he thought that this might be the source of the problem. In fact, it was. Measure- ments by utility consultants indicated radon levels in the house in excess of 100,000 Bq/m 3 — levels frequently found in underground mines. Such levels were unheard of in domestic settings. It was at this point, on December 19, the utility requested that the state look into the problem since the source of radiation was not of nuclear power origin. Alarmed at the high readings, Watras temporarily moved his family out of the home to allow the State of Pennsylvania Radiation Protection Office to conduct its own survey and to investigate the situation more fully. The office arranged to visit the house on December 26. They took several measurements and confirmed the high readings recorded by the utility consultants. Additional surveys reconfirmed these findings. A review of the available literature indicated that, for residential structures, the Watras home had the highest level ever found in a private residence. At the time the high radon levels were discovered in the house, Watras and his family had lived in the home for approximately one year. Based on the exposure measurements in the home, the State Radiation Pro- tection staff estimated that Watras and his family incurred a 10% lifetime risk of lung cancer during the one year they had lived there. On January 5, 1985, the Office of the Secretary of the Pennsylvania Department of Environmental Resources officially rec- ommended that Watras and his family vacate the residence. The Philadelphia Electric Company and Bechtel Inc., the contractor employing Watras, assisted in providing living arrangements for the family until corrective actions in the home could be taken. The house was eventually remediated and made suitable for occupancy although “it was a nightmare medically and financially” according to Watras. The Watras family was able to move back into their home on July 3, 1985, after an absence of six months. During that time extensive remedial action was taken to reduce the radon concentra- tions in the home at a cost of about $32,000. Remedial actions in the home were remarkably successful, reducing the radon concentration almost 700-fold to levels near the EPA-recommended action level of 150 Bq/m 3 . The remedial action program was conducted in four phases over a six-month period. In phase I, a radon barrier was put in place around the foundation to stop radon gas seepage into the home. In phases II and III, all cracks in the basement floor were sealed, and a ventilation system was installed. The last phase consisted of the installation of another subfloor venti- lation system. Radiation monitors were placed in the house to measure indoor radon levels and to alert the Watras family of any increases in radon concentrations. Within two years of the discovery of the Watras house, over 18,000 homes were screened by the state of Pennsylvania to estimate the extent of the radon problem. Approximately 59% of these homes had levels in excess of the EPA remediation action level of 150 Bq/m 3 . Consequently, the state embarked on an educational and remediation effort in homes with high radon levels. The Watras home stands as a monument to radon as an indoor air pollutant. Numerous epidemiologic studies of uranium miners in the U.S., Canada, Europe, and Scandinavia have shown that high radon levels in mines are associated with 7977_C008.fm Page 151 Thursday, September 14, 2006 2:44 PM © 2007 by Taylor & Francis Group, LLC 152 Radiation Risks in Perspective increased lung cancer in miners. These high radon levels were never considered an environmental problem. Radon levels in the Watras home were comparable to levels of radon measured in some mine settings. This startling observation suggested that perhaps environmental radon might be a significant public health problem. Although no other homes in the Pennsylvania radon survey, or in any other state surveys, had levels as high as in the Watras home, EPA suggests that about 3 million homes (roughly 5% of the U.S. housing stock) have concentrations high enough to recom- mend that the homeowner take remedial action to reduce indoor radon levels. HUMAN EXPOSURE TO RADON Airborne radon and its decay products are ubiquitous. Radon gas is a product of the radioactive decay of naturally occurring uranium in the Earth’s crust. As a gas, radon is able to migrate through the soil and enter the atmosphere. The major radon exposure pathway for humans is inhalation of radon progeny in indoor air, usually in the home setting. The distribution of radon in homes is lognormal (Figure 8.1). FIGURE 8.1 Distribution of radon in homes. The concentration of radon gas in U.S homes is consistent with a lognormal distribution (i.e., the logarithm of the radon concentration is normally distributed). The lognormal distribution has a long tail at high radon concentrations indicating that the vast majority of houses have radon levels very close to zero. Fewer than 3% of U.S. homes have radon levels in excess of 300 Bq/m 3 . The lognormal distribution was generated assuming a geometric mean radon concentration of 35 Bq/m 3 and a geometric standard deviation of 2.84 (see Nero, A.V. et al., Distribution of airborne Radon-222 concentrations in U.S. homes, Science, 234, 992, November 21, 1986) using the R project for statistical computing statistical 7977_C008.fm Page 152 Thursday, September 14, 2006 2:44 PM © 2007 by Taylor & Francis Group, LLC software R version 2.0.1. http://www.r-project.org/ (accessed March 2006). Radiation from the Gods 153 About 95% of U.S. homes have radon levels below 150 Bq/m 3 , the level recom- mended by the EPA for home remediation. 6 Radon levels in homes can vary by as much as four orders of magnitude. The long tail in the skewed distribution indicates that only a small percentage of homes has high radon levels. Fewer than 3% of homes have levels in excess of 300 Bq/m 3 . The wide range of domestic radon levels is due principally to two factors. The most important factor is the source strength as measured by the rate at which radon gas enters the home from the soil, domestic water, and building materials. The second factor is the ventilation rate in the home or building. In areas where high uranium concentrations in soils exist it is likely that radon levels are also high. If uranium concentrations in soils are very low, then it is also likely that radon in these areas is also low. But soil content alone is not a good predictor of radon levels in homes because of the influence of other key factors. 7 Apparently the only way to determine radon levels in a particular house is to make measurements in that house. Areas with potentially high radon levels are scattered throughout the U.S. The Reading Prong (a large interstate region including Eastern Pennsylvania, New Jersey, and southern New York State), the Colorado plateau region, and central Florida are well-known areas with high soil levels of radon. The Watras home is located in the Reading Prong. Although the house recorded extraor- dinarily high radon levels, surveys of homes in nearby communities indicated sig- nificant variability in indoor radon levels. One home nearby had radon levels several hundred times lower. Such variability in radon measurements, even in areas with geologic settings predicting high radon levels, suggests that random house measure- ments of radon may be inadequate in determining the radon levels in a specific home. The indoor concentrations of radon are almost always higher than outdoor concentrations mainly because mixing and dilution are minimized indoors. Radon gas can enter houses in a number of ways, including through cracks in solid floors and in walls, particularly below ground level, through gaps around service pipes and suspended floors, and through construction joints and cavities in walls. Cellars in general show higher concentrations because they are near the source and also because ventilation there is poor. Family living spaces show concentrations that are entirely dependent upon the degree of ventilation. About four air changes per hour will reduce the indoor concentrations to values very near outdoor levels. In an effort to conserve energy by making houses tighter, radon concentrations have increased. HEALTH HAZARDS OF RADON The major health effect of exposure to radon is lung cancer. Lung cancer is one of the most common cancers and has a high mortality rate. More people die of lung cancer than from any other type of cancer. Only 10% to 15% of lung cancer patients live five or more years after diagnosis. According to 2005 American Cancer Society statistics lung cancer is responsible for 170,000 deaths annually in the U.S. Smoking accounts for about 150,000 cases, or 90%, of all lung cancer deaths. 8 If radon causes 20,000 lung cancer deaths per year as estimated by the EPA it would appear that the lung cancer burden can be entirely accounted for by smoking and radon. But it is well known that other agents, such as asbestos, also cause lung cancer. The EPA 7977_C008.fm Page 153 Thursday, September 14, 2006 2:44 PM © 2007 by Taylor & Francis Group, LLC 154 Radiation Risks in Perspective gets around this accounting problem by assuming that cigarette smoking and radon interact in a complex fashion in lung cancer development. The interaction is assumed to be more than additive (i.e., cigarette smoking and radon are not independent risk factors). In the EPA’s calculations, 90% of radon-induced lung cancers occur in smokers. Radon is the primary cause of perhaps 2,000 lung cancer deaths annually in never smokers. 9 The mechanism of radon carcinogenesis is now fairly well understood. Lung cancer results from exposure of sensitive broncho-epithelial cells in the lung to alpha radiation from radon and its radioactive progeny. The alpha particles cause extensive damage to the DNA of the target cells. DNA damage is such that the cells are not killed, but their growth characteristics are altered in a way that they begin to proliferate out of control. Although transformational injury is registered instanta- neously when radiation energy is absorbed, the clinical appearance of lung cancer does not occur for many years or decades. This latent period is a well-known characteristic of carcinogenesis. In addition to a long latency, lung cancer induced by radiation exposure is clinically and pathologically indistinguishable from lung cancers produced spontaneously or by exposure to other carcinogens such as ciga- rette smoke. What this means is that on an individual basis radiation exposure cannot be identified with certainty as the causative agent. Epidemiologic studies of large populations must be conducted to identify radiation as an etiologic agent in lung cancer by analyzing the differences in lung cancer mortality in exposed and unex- posed groups. The primary evidence for radon-induced lung cancer comes from extensive studies of uranium miners exposed to very high concentrations of radon gas. Studies have been conducted all over the world under different occupational exposure con- ditions. 10 Lung cancer risk estimates from each of these studies have been remarkably consistent in spite of differences in study populations and methods of analyses. Clearly there are problems extrapolating risks from mines to residential envi- ronments. People in houses are exposed to radon levels that are thousands of times lower than levels in mines. The air in mines is much different from the air in houses. Mines are closed environments characterized by high levels of dust particles, diesel exhausts, and other pollutants. Miners also were smokers, and cigarette smoking is the predominant cause of lung cancer. Separating out the contribution of radon in these populations as a cause of lung cancer has been extremely difficult. The utility of miner-derived risk estimates to predict risks in women and children is also problematic because miner populations were exclusively adult males. A number of epidemiological studies has been conducted in recent years to measure indoor radon risks directly. Major reports include pooled analyses of European, North American, and Chinese residential case-control studies. 11 These are difficult studies to conduct and interpret because radon levels are orders of magnitude lower than in mines (except for a small percentage of homes that have very high radon levels), and associated lung cancer risks are very small. Accordingly, risk uncertainties are quite large. Meta- analysis of indoor radon studies indicates that an LNT dose-response provides a good fit to the indoor radon data and that a significant association exists between radon concentration in homes and lung cancer mortality. But the uncertainties in indoor radon risks, particularly at low radon concentrations, are large enough to include the possibility 7977_C008.fm Page 154 Thursday, September 14, 2006 2:44 PM © 2007 by Taylor & Francis Group, LLC Radiation from the Gods 155 of zero risk. When combined effects between radon and smoking are considered, almost all of the radon risk accrues to smokers. Accordingly, it is unclear whether the domestic environment poses a significant health risk. The large background rate of lung cancer mortality due to cigarette smoking dwarfs any radiogenic risks. The EPA’s population estimate of about 20,000 lung cancer deaths per year due to radon contains substantial uncertainty because of the confounding effects of cigarette smoking and because the estimate is the product of mapping a highly uncertain radiogenic risk onto the entire U.S. population. 12 Figure 8.2 shows data from a pooled analysis of 11 miner studies and meta-analysis of residential radon studies. An LNT dose response can be fit to the miner and residential data with a positive risk coefficient. 13 However, it is also reasonable to conclude that the slope of the linear dose response is consistent with zero and that radon has no effect on lung cancer risk for radon concentrations up to about 400 Bq/m 3 because statistical uncertainties are large. Fewer than 2% of U.S. homes have radon concentrations greater than 400 Bq/m 3 . The large statistical uncertainties in the indoor radon data do not preclude zero health risk for radon concentrations less than 400 Bq/m 3 . In spite of the somewhat consistent findings of miner and residential radon studies, questions have been raised about whether radon is actually harmful at low levels. Bernard Cohen, a physicist at the University of Pittsburgh, argues that low levels of radon do not increase lung cancer deaths and instead appear to be beneficial by lowering death rates. Hormesis proponents used Cohen’s findings to support their position that the LNT theory is wrong and that low-level radiation is beneficial to health. Cohen’s approach differed significantly from more traditional epidemiolog- ical methods by using an ecological method to correlate residential radon levels and lung cancer mortality in 1600 U.S. counties. 14 This represents the single largest source of data on health effects of radon. FIGURE 8.2 Lung cancer risks and radon. Mortality risk from lung cancer is a linear function of radon concentration. Relative risks (RR) are derived from the meta-analysis of indoor radon studies and pooled analysis of underground miner studies. The light line (and accompanying light data points with 95% confidence limits) is the fitted exposure response from indoor radon studies; the dark line (and accompanying dark data points with 95% confidence limits) is the fitted exposure response from miner studies. The line at RR = 1 indicates no health effect from radon exposure. (Modified from Lubin, J.H. and J.D. Boice, Jr., Lung cancer risk from residential radon: Meta-analysis of eight epidemiological studies, Journal of the National Cancer Institute, 89, 49, 1997.) 7977_C008.fm Page 155 Thursday, September 14, 2006 2:44 PM © 2007 by Taylor & Francis Group, LLC 156 Radiation Risks in Perspective Cohen’s data clearly predict outcomes paradoxical to miner and residential stud- with a biphasic dose-response function characterized by an initial negative slope (low concentrations of radon reduce the risk of lung cancer) followed by a positive slope at higher concentrations of radon (high concentrations of radon increase the risk of lung cancer). Subsequent analyses of Cohen’s data showed that cigarette smoking was not completely accounted for and the initial negative slope of the dose response could be explained by the overwhelming confounding of cigarette smoking. 15 The National Research Council’s (NRC) BEIR VI committee’s estimate of 15,400 lung cancer deaths per year attributable to radon is the committee’s best assessment based on currently available data from miner studies. Uncertainty anal- ysis indicates that the number of cases could range from as few as 3,000 to as many as 32,000 (95% confidence limits) lung cancer deaths per year. 16 However, because of the large uncertainties the lower limit of uncertainty should include zero. 17 The BEIR VI report conclusions are entirely consistent with the current EPA radon policy by suggesting that: (1) radon exposure in the domestic environment is a substantial public health hazard, and (2) reduction of indoor radon concentrations to levels at or below the EPA action guide (150 Bq/m 3 ) may avoid a significant number of lung cancer deaths. However, epidemiological evidence to support these conclu- sions is either absent or not convincing. A more reasonable conclusion is that lung cancer risk is insignificant for radon concentrations below 400 Bq/m 3 (Figure 8.2). The EPA’s own estimates are based on the BEIR VI report. According to the EPA, radon accounts for about 13% of all lung cancer mortality. About 26% of all lung cancers in never smokers is radon related. EPA further estimates that 26% of the total risk would be avoided if all homes above 150 Bq/m 3 were reduced to 40 Bq/m 3 . 18 In spite of the fact that indoor radon is now recognized as the most hazardous pollutant in the indoor environment, there is a great deal of uncertainty underlying the severity of the so-called “radon problem.” There are no epidemiologic studies that provide direct, unequivocal evidence of increased lung cancer mortality at environmental levels of radon. The health hazard of indoor radon is primarily inferred from epidemiologic studies of miners exposed to high radon levels. IS THERE REALLY A PUBLIC HEALTH HAZARD? P UBLIC H EALTH Twenty thousand lung cancer deaths per year is a very large number and suggest that radon is a serious public health hazard. But is it? How realistic is the EPA’s estimate of lung cancer mortality? The EPA uses LNT theory to predict the number of cancer deaths based on the size of the population and risks derived from uranium miner studies. Multiplying a very large population by a small individual risk yields a large number of cancer deaths, even though only a very small residential radon be considered a public health hazard because the entire U.S. population is exposed to radon, even though average individual risks are very small? At average residential levels (approximately 50 Bq/m 3 ), radon is associated 7977_C008.fm Page 156 Thursday, September 14, 2006 2:44 PM © 2007 by Taylor & Francis Group, LLC ies. Instead of a positive slope (as shown in Figure 8.2), Cohen’s data are consistent percentage of people are subject to high radon exposures (Figure 8.1). Should Radiation from the Gods 157 with a lifetime risk of lung cancer death of about 0.2%. 19 This theoretical risk is small compared to health risks of smoking and obesity but is larger than the risks of many agents regulated by the EPA, including benzene, chloroform, and ethylene dibromide. The EPA’s radon responsibilities are codified in the Indoor Radon Abatement Act of 1988. The legislation establishes a long-term goal that indoor air be as free from radon as the ambient air outside buildings. This is a laudable goal but is technically not feasible — home construction cannot entirely eliminate suboptimal ventilation rates and differences in indoor and outdoor air pressure. The law autho- rizes funding for radon-related activities at the state and federal levels. 20 Individual states such as Pennsylvania and New Jersey now have extensive experience working with communities to provide home radon tests and to assist with remedial action programs. The EPA also established standards for radon testing and home remedi- ation to provide some assurance to homeowners that radon companies use govern- ment-approved methods. The EPA has established an indoor air action guideline of 150 Bq/m 3 . 21 The EPA’s action level was based on guidelines established by the U.S. Department of Energy (DOE) to remediate high radon homes located on uranium mill tailings in Grand Junction, Colorado. The level was also established based on considerations of what is technologically feasible in home radon remediation. Above the action level, EPA recommends that the homeowner consider possible remedial actions to reduce radon levels. The urgency in doing this depends on the radon levels found in the home. Unfortunately, the EPA guide is interpreted incorrectly as law or as a bright line indicating safety. The EPA guideline is just that — a guideline. The EPA recommends remediation if radon concentrations are above the recommended level, but homeowners are not required to do anything except in localities where real estate laws require home sellers to test their home and remediate as a necessary part of a real estate transaction. Homeowners have also assumed that the EPA has determined that homes with radon levels above 150 Bq/m 3 are unsafe. The guideline in no way implies safety or an unhealthy atmosphere. It is strictly an action threshold whereby renovations of the home may be advisable to reduce the radon concentrations further. There are no epidemiologic studies indicating that the 150 Bq/m 3 action level is detrimental to the public health. Comparing radon levels in homes to natural background levels is a useful metric for remediation decision making. A dose-based system avoids the need to estimate highly uncertain risks. 22 Guidelines for remediation are easily expressed as dose proportions where the EPA action guide of 150 Bq/m 3 is equivalent to a dose proportion of about 4, assuming a natural background level of radon of 40 Bq/m 3 . According to EPA policy, homes with dose proportions greater than 4 would be candidates for remediation. It should be reemphasized that the EPA action level of 150 Bq/m 3 was based on technical feasibility rather than any consideration of health risks. Remediation is not likely to provide public health benefit for homes with dose home radon concentration in air (in Bq/m 3 ) divided by the U.S. average residential radon level in homes (assumed to be 40 Bq/m 3 ). 7977_C008.fm Page 157 Thursday, September 14, 2006 2:44 PM © 2007 by Taylor & Francis Group, LLC A simple decision framework is shown in Table 8.2. Dose proportions are the proportions less than 10 (Figure 8.2). 158 Radiation Risks in Perspective Dose proportions are somewhat subjective but based on current dose-response about 400 Bq/m 3 (a dose proportion of 10). Any remedial action at radon concen- trations of 400 Bq/m 3 or lower is not likely to have measurable benefit in terms of reduced lung cancer risks. On the other hand, a dose proportion of 20 or more indicates significant radon concentration that would justify remedial actions. Dose proportions between 10 and 20 represent a gray area and decisions to remediate would be made on a case-by-case basis. Only a few percent of U.S. houses fall in the high-dose proportion category. Regardless of the dose proportion, the decision to remediate is a personal one. Dose proportion information provides important guidance, but the homeowner’s perception of the risk and willingness and ability to pay remediation costs are important drivers. P ERCEPTIONS AND F EARS There is widespread public apathy regarding radon exposure in homes. 23 The public response is perplexing because the public health implications of indoor radon expo- sure would appear to be serious, according to EPA estimates. Part of the problem is that radon is odorless, colorless, tasteless, invisible, and exposure causes no proximal health effects. It does not cause visible damage to the home — no discol- oration of walls or collection in piles like loose asbestos. Public and EPA perceptions of environmental problems differ. In 1992, the EPA considered radon, ozone, and air pollution as the worst environmental problems. The public cited local problems such as hazardous waste sites, exposure to toxic chemicals, and water pollution as the most serious problems. 24 Perhaps the reason for this general apathy is the fact that radon is a natural problem resulting from the decay of radioactive material in the earth’s crust. It is unrelated, for the most part, to technological activities. Other environmental prob- lems associated with hazardous waste sites are directly related to technologic activ- ities. The general public perceives these problems as very serious. If technology created the problem, then technology ought to solve it. With radon there is no one to blame for high radon levels. No specific business or industry can be targeted to seek relief from high radon levels. Since 1984, radon has received considerable public attention. But the public continues to deny the seriousness of the radon problem in spite of the EPA’s national TABLE 8.2 Remediation Based on Dose Proportions Dose Proportion Likely Effects Action > 20 Observable risk of lung cancer Remediation recommended 10–20 Low risk of cancer Consider remediation < 10 Risk is either zero or too small to be measured reliably No action necessary 7977_C008.fm Page 158 Thursday, September 14, 2006 2:44 PM © 2007 by Taylor & Francis Group, LLC data summarized in Figure 8.2. There is little justification for remediation below [...]... at the time of testing, and length of the testing period Basement readings are higher than readings on upper floors; readings tend to be higher in winter than in summer; long-term readings are more reliable than short duration tests If initial testing results are above the EPA action level, followup testing should be performed to verify earlier results Surveys of single-family homes indicate that homes... 7977_C0 08. fm Page 160 Thursday, September 14, 2006 2:44 PM 160 Radiation Risks in Perspective times lower than the EPA action level of 150 Bq/m3, and at least ten times lower than levels associated with measurable health risks These are meaningful comparisons that put a particular house reading into perspective for the homeowner without having to calculate uncertain risks ECONOMIC IMPACTS According to... radon Drunk driving Fall in the home Fire Drowning 15,000–22,000 12,200 9,300 3,200 900 Sources: U.S Environmental Protection Agency, A Citizen’s Guide to Radon, 2nd ed., EPA Air and Radiation Report ANR-464, U.S EPA, Washington, DC, 1992; U.S Environmental Protection Agency, EPA Assessment of Risks from Radon in Homes, EPA 402-R-0 3-0 03, U.S EPA, Office of Radiation and Indoor Air, Washington, DC, June... possible to determine who in the group has the disease in question and what their exposures were Furthermore, the contributions of confounding factors such as cigarette smoking cannot be fully evaluated See Cohen, B., Test of the linear nothreshold theory of radiation carcinogenesis in the low dose, low dose-rate region, Health Physics, 68, 157, 1995 15 Puskin, J., Smoking as a confounder in ecological... benefit to be gained by remediating these homes since health risks are already very small and there is little change in risk with decreasing radon levels (Figure 8. 2) Clearly homes that far © 2007 by Taylor & Francis Group, LLC 7977_C0 08. fm Page 164 Thursday, September 14, 2006 2:44 PM 164 Radiation Risks in Perspective exceed the EPA action level (for example homes with radon levels at 80 0 Bq/m3 or higher)...7977_C0 08. fm Page 159 Thursday, September 14, 2006 2:44 PM Radiation from the Gods 159 radon campaigns The EPA has used aggressive tactics to scare the public into taking action Billboard messages such as “Call 1 -8 00-RADON!,” and “Radon is a health hazard in your home,” have appeared, as have Ad Council messages in broadcast and print media In 1 988 , together with the U.S surgeon... Exposure to Ionizing Radiation, BEIR V report, National Academy Press, Washington, DC, 1990 18 Supra note 2 19 EPA report presents new radon risk estimates, Health Physics News, 32(1), 1, January 2004 © 2007 by Taylor & Francis Group, LLC 7977_C0 08. fm Page 166 Thursday, September 14, 2006 2:44 PM 166 Radiation Risks in Perspective 20 The Indoor Radon Abatement Act of 1 988 authorizes the EPA to administer grants... Indoor Air, Washington, DC, June 2003 3 Nero, A.V., Controlling indoor air pollution, Scientific American, 2 58, 42, 1 988 4 National Research Council, Health Risks from Exposure to Low Levels of Ionizing Radiation, BEIR VII Report, National Academies Press, Washington, DC, 2005 5 This description of the Watras case was taken in large part from Reilly, M.A., The Pennsylvania Experience with Indoor Radon,... registered in this mining population 11 Lubin, J and Boice, J.D., Lung cancer risks from residential radon: Meta-analysis of eight epidemiological studies Journal of the National Cancer Institute, 89 , 49, 1997; Krewski, D et al., Risk of lung cancer in North America associated with residential radon, Epidemiology, 16, 137, 2005; Lubin, J et al., Risk of lung cancer and residential radon in China: pooled... and will incur additional, more expensive testing to verify accurate radon levels The EPA uses risk comparisons to put residential radon risks in perspective Risk comparison can be a powerful means of communicating risks to the public if the comparisons are valid To indicate the seriousness of the radon problem, the EPA compared radon risks with other risks familiar to the public (Table 8. 3) Risks are . the time of testing, and length of the testing period. Basement readings are higher than readings on upper floors; readings tend to be higher in winter than in summer; long-term readings are more. Test of the linear no- threshold theory of radiation carcinogenesis in the low dose, low dose-rate region, Health Physics, 68, 157, 1995. 15. Puskin, J., Smoking as a confounder in ecological. variability in radon measurements, even in areas with geologic settings predicting high radon levels, suggests that random house measure- ments of radon may be inadequate in determining the radon