But much of this is discredited or discounted by evidence reviewed by the National Research Council (Biological Effects of Ionizing Radiation - BEIR IV). Washington, DC; National Academy Press, 1988, pp. 168-171 and 436-441).

A metabolic ward study showed that tobacco smoking amounted to only a small percentage of the exposure to polonium-210 from ordinary food (RB Holtzman et. al. Health Phys 1963;9:385-400; and Third International Congress of the International Radiation Protection Assoc. AEC CONF-730907-P2. Washington, DC: Atomic Energy Commission, 1974 pp 1406-1411).

Because of this exposure from food, there is little or no difference in overall body tissue alpha emitter concentration between smokers and non-smokers. Measured concentrations in smokers are below the level of biological significance, including in the lungs (JB Little et al. Radiat Res 1964;22:209).

So-called "hot spots" in smokers are speculations, and these "possible hot spots" would only be "possibly biologically significant." But no difference between smokers and non-smokers was actually found at bronchial bifurcations, where most tumours arise (CR Hill. Nature 1965;208:423-428). Lung tumours incidence was dramatically reduced in dogs exposed concomitantly to high levels of alpha emitters and tobacco smoke, compared to those not exposed to smoke (FT Cross et al. Health Phys 1982;42:35-52).

Gladys Block of the National Cancer Institute lied outright by claiming that attachment of radon daughters to secondhand particles increases the risk to non-smokers, because all evidence shows that unattached radon daughters are more hazardous than the attached ones.

With great palpitations, she told the public that if they had high radon levels in their homes, they should never allow smoking there. Tobacco smoke "even attracts radon particles for inhalation," she screeched. Assistant Surgeon General Vernon J Houk proclaimed, "Do not allow smoking in any house that has detectable levels of radon." He also claimed that there were 5,000 non-smoker lung cancer cases from radon, and that smokers' risk is 15 times higher.

Although BEIR IV claimed a multiplicative effect of smoking, it was based on extrapolation from less reliable dosimetry in miners. Residential radon has not turned out to be the danger that they predicted. In an overview of published studies, "The highest percent of positive significant findings was for house type (83.3%); the lowest percent was for radioactive wastes (16%). Only 22.2% of studies involving measured radon levels were significantly positive. The two best studies yield partially conflicting results. One of them shows a positive trend in risk, while the other shows no increase in lung cancer risk with radon levels." And, among the 41 studies cited, "Results of different studies were contradictory with respect to the combined effects of radon exposure and smoking on lung cancer." (JS Neuberger. Cancer Detect Prevent 1991;15(6):435-443).

All house type studies findings risks were from Sweden (7 studies with 883 cases). They are inconsistent regarding smoking. A Maryland study with 298 cases found no risk from radon.

Those two best, in China and in New Jersey with 308 and 443 cases respectively, were case-control studies with measured indoor radon levels. In the first, "No association between radon and lung cancer was observed regardless of cigarette-smoking status, except for a non-significant trend among heavy smokers." Heavy smokers are defined as "those who smoked >/= 20 cigarettes for >/= 30 yr or smoked for >/= 40 yr." (WJ Blot et al. JNCI 1990;82:1025-1030). They added. "Our data suggest that projections from surveys of miners exposed to high radon levels may have overestimated the overall risks of lung cancer."

The other found a trend with high exposure, but this weakened when cumulative radon exposure was calculated, and also when analyses were limited to the 346 cases and 318 controls with actual living area (rather than basement) alpha track measurements (JB Schoenberg et al. MMWR 1989;38:715-718; and Cancer Res 1990;50:6520-6524).

"Taking spouse smoking into account did not result in any changes in the nonsmokers' pattern of radon-related risk." There was a negative trend for smokers of 25+ cigarettes per day, with an OR of 0.4 for the most highly exposed, which is the opposite of the China study. The positive trend for non-smokers is also contrary to the China study.

The largest case-control study, with 25,398 cases, found significant 2.0 and 1.5 RRs for white male non-smokers and ex-smokers in a region of Florida with high radon levels. There was non for either male smokers, or for females regardless of smoking (HG Stockwell et al. Am J Epidemiol 1988;128:78-84).

Several new studies have appeared since the Neuberger review. Swedish case-control studied with 586 female and 774 male cases (G Pershagen et al. NEJM 1994;330:(3):159-164), and of Stockholm only (Health Phys 1992;63(2):179-186) with 210 female cases claimed risks to smokers and non-smokers similar to estimates based on studies of miners, of up to 1.8.

However, house type was used for 27.4% of dwellings which lacked measurements.

An ecological study of 20 Iowa counties (JS Neueberger et al. Health Phys 1994;66:(3):263-269) found a 33.2% reduction in lung cancer in counties with low smoking rates, and a 24% increase in counties with high smoking rates, with increasing radon levels.

An ecological study of 911 US counties (BL Cohen, GA Colditz. Environ Res 1994;64(1):65-89) found that "The data show a very strong tendency for lung cancer rates, corrected for smoking prevalence, to decrease with increasing r, in sharp contrast to the opposite behaviour predicted by the theory."

Contrary to the Swedish studies, they found no confounding between radon levels and smoking rates.

None of the existing studies are considered definitive. But there is little justification for any alarm for any residential radon, including among smokers. Radon researchers themselves are fiercely critical of the EPA. "The Environmental Protection Agency has perpetrated a fraud. Everything is exaggerated -- from the number of homes at risk to the individual's risk from radon," says Anthony V Nero (Parade, Nov 4, 1990, p 10).

Courtesy of Carol Thompson 08/23/93
Smokers' Rights Action Group
P.O. Box 259575
Madison, WI 53725-9575
Phone: 608-249-4568