Second-largest cause of lung cancer is right under your feet

Ask people what causes lung cancer and they’re likely to correctly reply “smoking.” But chances are, they won’t know the second-leading cause of lung cancer: radon. This odorless, invisible gas is responsible for about 21,000 lung cancer deaths annually, according to the Environmental Protection Agency (EPA).

“To place this into perspective, this is twice the number of deaths annually from drunk driving (10,497) and exceeds that of many other, more-publicized causes of death, eg, homicides (17,250),” researchers wrote in a recent meta-analysis in the Journal of Environmental Radioactivity.

Although most people are aware of radon, many segments of the population—particularly people under age 30 and those with less education—don’t know what radon really is. Of those who have heard of radon, most reported that they didn’t know radon causes lung cancer.

“Rates of radon testing and mitigation are correspondingly low and appear to reflect cognitive defense mechanisms by which individuals believe that their risks from radon are lower than the risks faced by others,” wrote the authors of the meta-analysis, Nancy Vogeltanz-Holm, PhD, and Gary G. Schwartz, PhD, MPH, PhD, both of University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND.

Danger in the ground

Radon is a naturally occurring radioactive gas produced by decaying uranium and thoron in the earth. The gas enters homes through cracks in foundations, and breathing it for prolonged periods causes health consequences. According to the EPA, about 1 in 15 homes in the United States has radon that is at or above dangerous levels.

For their review, the researchers included 20 studies that assessed whether individuals had heard of radon and knew it caused cancer—and, if they did know, whether they tested for it or mitigated it.

“In many reports we reviewed, the answer to both these questions is ‘No’,” wrote Drs. Vogeltanz-Holm and Schwartz.

“For example, among the nearly 1,000 individuals who had ‘heard about radon’ in New York State between 1995 and 1997, only 21% knew that it causes lung cancer,” they added. “In Washington State in 2004, more than 70% of individuals had heard about radon but an equal percentage did not know how to test for it, and in Vermont in 2007, half of the respondents who had tested for radon and had actionable radon levels apparently did not know that it causes lung cancer.”

A survey among a random sample of Florida homeowners who lived in a high radon county found that 64% reported concern about radon and as many as 70% knew that it caused lung cancer. Yet only 7% reported testing for it. Their main reasons for not testing were “not having gotten around to it” (43%) and that they believed that radon wasn’t present in their homes (43%).

About half of respondents in many studies said they think radon causes headaches (which it doesn’t). People are likely confusing it with the effects of carbon monoxide, the researchers speculated.

“Since radon and carbon monoxide are both invisible, toxic gases, this confusion is understandable. However, because headaches are rarely fatal, this misunderstanding may contribute to the mistaken belief that the threat of radon is not serious,” Dr. Vogeltanz-Holm and Dr. Schwartz wrote.

What can be done

Given the public’s unawareness of and/or indifference to the health effects of radon, the authors offered several public health recommendations.

1. Standard sources of information about radon (eg, brochures published by the EPA) need to be revised. At the very least, educational efforts should emphasize that household smoke and carbon monoxide detectors do not detect radon.
2. Home buying can be used as a window of opportunity to encourage radon testing and remediation. Indeed, radon testing is required in 29 states for the sale of a home.
3. Newer technology that makes radon testing less complicated may increase remediation. For example, digital radon detectors that provide measurements in real time (and don’t require mailing a test kit to a laboratory) are affordable to many home owners at a cost of $150 or less.

“We speculate that home placement of radon detectors that produce visible or audible alarms to signal high radon levels could promote remediation by providing the missing sensory cues that hitherto have hindered radon remediation,” the authors concluded. “The feasibility and effectiveness of such approaches may be a promising area for future research.”