Strange Glow

by Timothy J Jorgensen

  The EPA’s well-publicized claim that radon is the second leading known cause of lung cancer, after smoking-related causes, was also misleading. Although the statement is strictly true, it implies that the leading cause of lung cancer among nonsmokers is radon exposure. This interpretation is false. Radon is estimated to account for 26% of lung cancers among nonsmokers. The other known causes are second-hand smoke (27%), occupational exposures to airborne carcinogens (4%), or breathing outdoor air pollution (2%). The largest proportion of lung cancers among nonsmokers is actually due to other causes that are currently unknown (40%).24 In fact, cigarette smoke, even when breathed second hand, is taking its toll on the nonsmokers too. And the only reason that radon ranks second among the so-called known causes is because the bulk of the causes of lung cancer in nonsmokers remains unknown. So, lung cancer among nonsmokers is rare, and radon-induced lung cancer among nonsmokers is rarer still. See any pattern here? Smoking is extremely bad for your health. If you want to prevent lung cancer, get rid of smoking, and the radon problem will largely resolve itself.

  Many of the scientists and risk assessors felt that the EPA had twisted the facts to advance its own agenda and were using scare tactics as public policy. This resulted in some pretty ugly fighting between the agency and the scientific community. The controversy spilled over into the public arena and led many people to the erroneous conclusion that the risks from home radon were not real; this was similar to the way climate controversies have led many to conclude global warming is a myth. Radon risks, like global warming, are not myths. They are real. But the level of the radon risk to homeowners was certainly overstated by the EPA, at least in the early years.25

  Why the EPA became obsessed with eradicating residential radon exposure is not completely clear. Some have suggested there were political motivations. For example, it has been charged that home radon eradication was a convenient foil for the Reagan administration because it allowed the administration to appear aggressive in fighting environmental hazards without having to confront industrial polluters.26 Some have cited personal interests of the politicians who pushed for strong anti-radon regulations, including Senator Frank Lautenberg. His home in Montclair, New Jersey, was on a lot that included radon-emitting landfill, generously provided years earlier by US Radium’s dial painting factory in nearby Orange, New Jersey. The landfill was a half-century-old “gift” to Montclair that kept on giving. It released radon to the overlying homes long after the company and all its workers were gone.27 Regardless of the political motivations, it clearly wasn’t the science that was driving the EPA’s radon scare campaign. In fact, many of the scientists who had helped write the reports that the EPA was citing believed that the agency’s national radon policy was misguided.28

  The EPA’s actions caused some scientists, including Philip H. Abelson, former science advisor to the American Association for the Advancement of Science and editor of the journal Science, to lose faith in the agency. In 1991, Abelson published a particularly vitriolic attack on the EPA’s radon policy and the agency itself, in which he suggested that risk assessment studies for radon should be taken out of the EPA’s hands and given to the National Institutes of Health. He rightly claimed that the EPA’s radon policy caused “needless anxiety for millions of people,” and that it was “inexcusable [that the EPA] did not differentiate between radon’s effects on smokers and nonsmokers.”29 Abelson’s contempt for the agency was palpable: “One of the weaknesses of the EPA is that it seems to be unable to learn.”30

  Thirty years later, the rhetoric has died down and the EPA is still responsible for protecting the public from radon risk, but it does seem to have learned its lesson. A visit to the EPA’s public radon website today reveals that it is doing a better job at accurately characterizing the risk of radon, and it is more candid about the fact that radon is primarily a problem for smokers. The EPA has not, however, relaxed the 4 pCi/L (150 Bq/m3) action level for radon in homes, which remains in line with the most recent report of the World Health Organization (WHO) that recommends home radon concentrations worldwide not exceed 8 pCi/L (300 Bq/m3), and preferably be reduced to 2.7 pCi/L (100 Bq/m3).31 The WHO report, at least, acknowledges it is “important information to communicate [to the public that] the majority of radon-related lung cancer deaths occur in current and former smokers.”32

  ANOTHER KIND OF HARM

  The Watras family members were probably the main victims of the EPA’s gross miscommunication of risk. They were led to believe that their lives were in serious peril, and they carried that psychological stress with them even as they left their home for a safer environment. The truth is they suffered a moderate increase in cancer risk from their radon exposure, which was hardly a death sentence. If this had been a medical diagnosis, their erroneous prognosis would have been called a false-positive result (i.e., falsely determined to test positive for a fatal disease). Presently, we’ll learn how diagnostic radiology is grappling with the problem of false-positive diagnoses, which often result in very high financial and psychological costs for both the individuals misdiagnosed and for the health care system in general. The environmental protection community has not been held accountable in a similar way for the consequences of their overly conservative risk predictions. But the societal costs are equally as large.

  Whatever happened to the Watras family? Once the family moved out of the house, the EPA used it as a testing laboratory for various radon remediation technologies. After many months, the agency was able to lower the radon levels to 4 pCi/L, the recommended limit, and the Watras family moved back in. Stanley and his wife Diane are still living in the house (as of 2015). Their children are now grown. After 30 years, none of them has died of lung cancer, although the EPA risk estimates for the one year that they had lived in the house suggested that nearly all of them would have done so by now. How could the dire predictions for the Watrases have been so off the mark?

  This is one of the trade-offs of using multiple, highly conservative assumptions in risk assessment. It may seem prudent to inflate the risk in order not to underestimate it. Nevertheless, by adopting high-end estimates for every uncertain risk parameter, the cascade of high-end risk assumptions can compound to the point where the final predicted risk levels become incredulous and may even defy common sense.33 For example, according to the EPA’s risk estimates, just one year of living in the Watras house (16 WL) would put a smoker’s lifetime lung cancer risk from radon exposure at 56%,34 in addition to his lung cancer risk from the smoking (15 to 50%, depending upon his smoking level), making his overall lung cancer risk as high as 100%. But as Naomi Harley, a professor in the Department of Environmental Medicine at New York University has pointed out, the lung cancer death rates for miners with the highest radon exposures ever recorded (nearly all of whom were smokers) were never greater than 50%.35 Thus, estimates of lung cancer risk from radon in homes that exceed 50% must be considered suspect.

  WHERE TO NEXT?

  In this first chapter of Part Three, we began our journey into weighing radiation’s risks and benefits by considering radon in homes. Why start with radon? We did this for three reasons: (1) radon was among the very first radiation hazards identified; (2) the exposed populations have been recognized—miners and residents of radon-contaminated homes—and their exposures have been measured; and (3) nearly a century of cohort studies defines the dose ranges where human health problems would be expected to occur. These are three legs of a four-legged table that professional risk assessors use to evaluate health risks and draw conclusions. The fourth leg is to accurately characterize the risk level to the people who have some interest in the risk assessor’s findings; they are often referred to as the stakeholders, whether they are health professionals, government regulators, or the public at large. It is this fourth leg of the table that has proved to be the biggest challenge to professional risk assessors and risk managers. Even when the professionals get it right, their message is often terribly mangled by the time it reache
s the public arena. That was the situation with radon.

  Without a strong fourth leg, the risk assessment table wobbles, and all the legislation, regulation, and public safety initiatives that table supports are in jeopardy. There is also a danger of spawning exaggerated fear and even panic, which further exacerbates the problem.

  Another reason to start with radon in homes as a first example of a risk-benefit analysis is because determining the benefit side of the equation is relatively straightforward. It’s zero! There is absolutely no benefit from living is a radon-contaminated house. So for radon, the question is simple: How much risk is acceptable in the face of no benefit? In the next chapter, we’ll look at diagnostic radiography, for which the benefits to health are potentially enormous, and see how that affects the risk-benefit balance.

  CHAPTER 13

  A TALE OF TWO CITIES: DIAGNOSTIC RADIOGRAPHY

  Statistics can be made to prove anything … even the truth.

  —Noel Moynihan

  BOYS WILL BE BOYS

  It had been a good long snowboard run, without incident, through the exhilarating mountain air of Vail, Colorado. With the dangers of the slopes behind him, 13-year-old Matthew Piscator headed for the momentary safety of the chairlift to begin the journey back to the mountaintop for what would be his second run of the first day of a Rocky Mountain winter vacation. As he approached the lift line, he decelerated rapidly, and then culminated his ride with the abrupt turning motion that snowboarders use to hit the brakes. This was a maneuver he had not yet quite mastered. As he made the quick turn, his board stopped on command, but his torso failed to notice that his feet had changed direction. Falling backward, he reached behind his body with his left arm to break his fall. But his fall was not the only thing that was broken. When he heard the cracking sound, Matthew immediately knew his vacation had ended, even before he became conscious of the pain.

  If you’re going to break a limb, Vail is a good place to do it. The medical personnel in this city see broken bones every day, and they know just how to handle them. Within minutes, the ski patrol had Matthew’s arm immobilized and he was towed off to the resort’s medical center. That bones were broken was obvious, since his arm now seemed to have a second elbow just above the wrist. Such an unnatural bend could occur only if both bones of the forearm (the radius and ulna) had been affected. An x-ray of the arm confirmed the double break, and the doctor was able to ascertain that the breaks were clean, and, therefore, could be easily set. Anesthetics were administered, the broken bones coaxed back into alignment, and a cast applied from wrist to elbow. With pain pills in hand, Matthew was sent on his way. But his vacation wasn’t over after all. He was out on the snow again that very afternoon, but this time he was enjoying the mountain sights from the cargo bed of a dogsled with a professional musher working the brakes.

  Matthew’s experience with his snowboard was not unlike Willie Bragg’s mishap with his tricycle over 100 years earlier. And the remedy for their broken arms had also changed little; this amounted to bone manipulation guided by x-ray images. Both boys went on to regain full function of their arms, outcomes unlikely before the advent of x-rays. Two boys doctored with x-rays, and two boys benefited. Odds don’t get any better than that.

  But what about the cancer risks to the boys from those x-rays? For Willie, we don’t know anything about his radiation dose, except that it must have been much higher than Matthew’s. Modern x-ray machines give only a tiny fraction of the dose that the old Crookes tubes delivered. Consequently, Willie’s risk of cancer would also have been higher than Matthew’s. Willie did die of cancer at the age of 82, but from cancer of the prostate, an outcome hard to explain by irradiation of his arm.

  We can do a much better job at estimating Matthew’s cancer risk from his x-ray. Modern x-rays of broken arms give an effective dose of about 0.001 mSv to the patient. This is the first time we’ve encountered the term “effective dose.” What exactly does it mean?

  As you recall, the cancer risk estimates for radiation exposures are based largely on atomic bomb survivor studies. Unlike atomic bomb victims who received radiation doses over their whole bodies, most diagnostic radiography procedures expose only a small portion of a person’s body.1 In Matthew’s case, it was just his left arm that was exposed, so his risk is much less than if he had received the same dose over his whole body. How do we account for Matthew’s lower risk due to his partial-body exposure? We simply ask: “What fraction of a person’s whole body does one arm represent?” It turns out that an arm is about 5% of total body weight. Therefore, the risk associated with Matthew’s arm dose of 0.020 mSv is effectively the same fatal cancer risk as if he received 0.001 mSv to his whole body (i.e., 5% of 0.020 mSv). Simply stated, that’s what effective dose means.2 It’s a representation of the cancer risk from a partial body dose in terms of the whole-body dose that would produce the same risk level. The importance of knowing the effective dose is that it allows us to use our most reliable risk estimates—those from the atomic bomb survivor studies—to calculate the risk associated with partial body diagnostic radiography procedures. So, what is the bottom line for Matthew’s risk of contracting cancer at some point in his life from his arm x-ray?

  As we’ve already learned (chapter 9), atomic bomb survivor studies tell us that the risk of contracting a fatal cancer from a whole-body radiation exposure is about 0.005% per mSv. Therefore, Matthew’s lifetime risk of contracting cancer from his arm x-ray is:

  0.001 mSv (effective dose) × 0.005% per mSv = 0.000005%

  (or odds of 1 in 20,000,000)

  This suggests Matthew is more likely to win the megalottery than he is to get cancer from the x-ray exposure of his arm. As we already know, the number needed to harm (NNH) is simply the inverse of the odds, so the NNH for an x-rayed arm is 20,000,000 people. In words, this means that if 20,000,000 boys like Matthew broke their arms, just one of them would be expected to get a fatal cancer from his subsequent x-ray experience. How many people break their arms in the United States every year? About 1,300,000. So how many of these patients would we expect to develop a fatal cancer when the NNH for an arm x-ray is 20,000,000? None of them! How many will benefit from having an arm x-ray? All of them! Now you have all the information you need to decide whether arm x-rays for broken bones are worth the cancer risk.

  Of course, life is more than broken arms. How much of this arm story is translatable to other radiography procedures? As it turns out, at least for the risk side of the equation, a lot of it is. Effective doses have been calculated by dosimetrists—the professionals who estimate radiation doses—for virtually every standard diagnostic radiography procedure. These effective doses are available to the public in various publications and on the Internet, and are usually depicted in tables. In fact, some of these tables will also show the corresponding cancer risk in either percentages or odds. Unfortunately, few tables will show the NNH, but we now know how to calculate that for ourselves from the risk percentages. For most diagnostic procedures the NNH will be very high, suggesting very low risk. So for diagnostic radiography procedures, getting a handle on the risk is not a problem. Quantifying the benefits is another matter; you will find no comparable tables for this. Why not?

  It turns out that the benefits of diagnostic radiography are more slippery than the risk, which is simply and objectively defined as the lifetime risk of getting cancer. Definitions of the benefits of radiography are more elusive. If only all the benefits of diagnostic radiography were defined as simply as “restored use of an arm”! The problems with quantifying benefits are threefold: (1) there is a huge range of benefits from diagnostic radiography, all the way from finding a curable disease before it becomes untreatable to documenting a medical condition for litigation purposes; (2) no two people see benefits in exactly the same way; and (3) the research on quantifying radiation’s benefits has sorely lagged behind research into measuring its risk. Because of these problems, when it comes to weighing risk versus benefits of diagnostic
radiation procedures, it’s hard to find a numerical benefit scale that isn’t broken. In most cases, the risks are highly defined and quantified, but the benefits are in the eye of the beholder. Nevertheless, one thing can be said with confidence: When it comes to using diagnostic radiography for finding the cause of clinical disease symptoms, the benefits almost always far outweigh the risks, largely because the risks are so very low. The only exception to this would be when a doctor orders an unwarranted diagnostic procedure. In that case, the patient receives a risk with no potential for benefit. Not good.

  TAKING YOUR LUMPS

  By the time Matthew returned to his hometown of Bethesda, Maryland, his arm was already on the mend. He was in nearly top form by the time spring baseball season rolled around, and he resumed his position as catcher, no worse for wear. Now it was his mother’s turn for some x-rays.

  Matthew’s mother, Teresa, is very health conscious. She eats well, exercises regularly, and worries a lot. Mostly she worries about her health. Teresa is in her 50s, and a number of her friends and acquaintances have contracted cancers of various types in the last few years. She knows that cancer risk increases with age, so she’s taking no chances. She’s an advocate of cancer screening, particularly cervical and breast cancer, both major killers of women. Other than her age, she is not in any elevated risk group for either type of cancer, but she feels “one can never be too careful when it comes to cancer.” She is lucky in that regard. Bethesda is the home of the National Institutes of Health campus, which lies in the heart of the greater Washington, DC/Baltimore metropolitan area, and she has access to some of the best health care systems and hospitals in the nation, all of which provide cancer screenings.