The Cancer Chronicles Read online

  Ever since I had my house tested for the gas two decades ago, registering a modest amount, I had paid little attention to the warnings. Radon, like carbon monoxide, is an invisible, odorless, silent killer—albeit one that works slowly as mutations mount year by year. Of the approximately 160,000 lung cancer deaths each year in the United States, the Environmental Protection Agency has said that 21,000, or 13.4 percent, may be radon related. What you don’t often hear is that for about 90 percent of those deaths smoking is also a factor. Through all the years of my life, I had smoked a grand total of maybe ten cigarettes—and none during the last twenty-five years. Still, as I began to learn more about cancer, I felt a need to conduct another radon test—this time in a room where I had recently been sitting for weeks writing this book.

  It had been an unusually cold winter in Santa Fe. Access to my second-story office requires traversing an outdoor staircase. It’s an easy and picturesque commute but sometimes it involves shoveling snow. For that and other reasons I had taken to working downstairs in a room that was built, like many in old Santa Fe, over a dirt crawl space. Two walls of the room are about six feet below ground level and built from adobe bricks molded from the same dirt that lay beneath the floor. For weeks the weather outside had been too cold for opening windows, and I had latched shut a door between the office and the hallway to hold in heat. The conditions, in other words, were likely to result in stagnant air and maximum readings of radon gas.

  I ordered a test kit, placed it on the desk, and forty-eight hours later mailed it to the laboratory named on the instruction sheet. This time the results that came back were more than quadruple what they had been before: 22.8 picocuries per liter. The EPA’s scale, correlating radon levels with risk, topped off at 20, and remedial action was recommended at just 4 picocuries per liter. A curie is approximately the amount of radiation produced by a gram of radium, so a picocurie is one-trillionth of that: 2.2 nuclear disintegrations per minute. As radon rapidly decomposes, it shoots out alpha particles (clusters of two neutrons and two protons) and breaks down into smaller elements, which float through the air emitting alpha particles of their own. They don’t travel far—alpha rays can be stopped with a sheet of paper—but because of their massiveness they deliver a heavy blow. The radon gas itself is readily expelled from the lungs, but the daughter particles, inhaled with every breath, can stick in the wetness and irradiate cells. Every minute in every liter of that stagnant air, fifty of these submicroscopic explosions were occurring. The EPA chart that came with the test kit informed me that if one thousand people who have never been smokers are exposed to 20 picocuries per liter throughout their entire lives, thirty-six of them would be likely to get lung cancer. Another way of saying it is that the lifetime risk is 3.6 percent. (For smokers exposed to that much radon the odds are seven times greater.)

  As I thought about these numbers, I began to feel a tightness in my chest. I imagined my lungs heavy with a miasma of cold, radioactive air. Compared with the astronomical amount of atoms in one breath of air, the fifty radioactive events occurring every minute is a vanishingly tiny proportion. And only a fraction of the shrapnel, these alpha particles, would strike lung tissue and cause genetic mutations. Most mutations, I reminded myself, are harmless. Our DNA is mutating all of the time. Cells have evolved mechanisms to repair broken DNA or to destroy themselves if the damage is too great. Of all the mutations that occur in a genome only certain combinations might trigger a cancer, and only if many other things go wrong. But for all of those reassurances there still was a palpable risk.

  The test had been done under such airtight conditions that the reading was bound to be abnormally high. Half a year later, in warmer weather, I measured again. This time I placed the detector in the bedroom (where Nancy and I had slept for seventeen years). I opened and closed doors and windows according to my usual routine. The measurement this time, closer to normal conditions, was much lower—7.8 picocuries. A third reading, in the hottest part of summer, when fans were circulating air through the house, came in at just 0.8 picocuries—way below the national mean. The average of my three readings was 10.5 picocuries (a risk of 1.8 percent). My odds were looking better and I wondered if I could lower them a little more.

  The EPA numbers are based on the assumption that people spend, on average, 70 percent of their time at home—nearly seventeen hours a day. That would be high for someone commuting to a full-time job. I work at home but most often I am upstairs, where my exposure would presumably be much less. Radon comes from the earth and is eight times heavier than air. With no interior staircase or forced-air heating, I felt safe in my office aerie. When I am downstairs I am often in parts of the house where radon levels are also probably lower. (Maybe I will buy more test kits.) To allow for all of that, I cut my estimated exposure—reducing it by one-fourth seemed reasonable—and then I cut it again. I’ve lived in the house for only about a third of my life. Dividing by three brought the level down to 2.6 picocuries—below the EPA “action level”—and my risk to about 0.3 percent. The chance of a nonsmoker getting lung cancer sometime in life is usually put at around 1 percent or less. If so, then living in this comfortable old house might have raised my odds to something like 1.3 percent, from a minuscule risk to a somewhat less minuscule one. But I guess that is a self-centered view. Spread across the population that would account for a lot of cancer.

  My calculations were rough. If I wanted to estimate more precisely, I would have to consider every other place I have lived. I had a basement bedroom when I was a child, but I’d lived on the fourth floor of a row house in Brooklyn and the eighteenth floor of a high-rise in Manhattan. It would be possible in theory to calculate long-term exposure with a laboratory analysis of my eyeglasses. When alpha particles strike carbonate plastic lenses they leave tracks—memories of radiation exposure. The tracks—there are typically thousands per square centimeter—can be translated into radon readings. There is also a method using ordinary household glass. Radon decay products are deposited on mirrors, picture frames, and cabinet windows and can become incorporated into the glass. By measuring the amount that has accumulated and considering other variables, epidemiologists can estimate how much radon people have been exposed to over many years—not just in their current homes but for as long as they have owned the objects.

  As I thought about all the microscopic wallops I might have incurred, I wondered where the EPA had gotten its figures in the first place—so many picocuries per liter corresponding to so many lung cancer deaths. It’s not like you can lock a thousand people in a basement and then wait for some of them to get cancer. The story began in the 1970s when houses in Grand Junction, Colorado, built on top of tailings salvaged from uranium mines, were found to have elevated levels of radon. At great expense the radioactive fill was removed and replaced, but the radon readings remained high. Then came a much reported incident with a construction engineer named Stanley Watras. He was working in 1984 at a nuclear power plant in Pennsylvania. As the plant neared completion, radiation alarms were installed, and they sounded whenever Watras passed by. The reactors, however, were not yet operating and there was no fissionable material in the plant. The source of the contamination turned out to be his house, which measured as high as 2,700 picocuries. You didn’t need to build on uranium tailings to have radioactive air. Homes across the country were found to register positive for radon, and it was coming from the natural soil. Radon has been with us from the start.

  In an attempt to gauge how threatening the exposure really was, epidemiologists began conducting case control studies, comparing radon levels for people who had contracted lung cancer with people who had not. Early results were inconclusive—some detected a small effect and others did not. A study in Winnipeg, which had the highest radon levels of eighteen cities in Canada, found no influence on lung cancer. Other researchers compared the average radon levels of different geographical areas. Again no association was found. A nationwide survey reported a negative correlatio
n, as though breathing radon somehow provided protection. Or else the study was flawed. Some critics suspected that the results were skewed by an inverse connection between smoking and the amount of radon measured in homes. Perhaps cigarette smoke interfered with the radon monitors, or smokers were more likely to occupy older, draftier houses or to open more windows.

  Getting better numbers would require either very large populations or very high radon levels—the hundreds to thousands of picocuries per liter that can be found in underground mines. Looking for answers, researchers studied lung cancer rates among uranium miners in Colorado, New Mexico, France, the Czech Republic, Canada (an area on the shore of Great Bear Lake had the evocative name Port Radium), and Australia (Radium Hill). They studied miners of other ores in Canada, China, and Sweden—altogether 68,000 men. Of those, 2,700 had died from lung cancer. That is about 4 percent. There were confounding factors to consider. Most of the miners were believed to be smokers but the data on how long or how often they had smoked was sparse or nonexistent. Miners are also exposed to diesel fumes, silica, and other dust, which might have synergistic effects. Laborers breathe harder than someone cooking dinner or reading a book in bed.

  Doing their best to adjust for these complications, a committee of the National Research Council began analyzing the numbers and quantifying the relationship between radon and lung cancer. They assumed that it must be linear—that one-tenth the exposure leads to one-tenth the risk. Not all toxicologists believe that is true, proposing instead that there is a threshold below which radiation causes no damage. But the mainstream view is that even the smallest amounts are potentially harmful. With marathon feats of statistical calculation, the numbers for the miners were adjusted downward to estimate the risk from the far lower exposures found in homes. That was the basis for the chart distributed by the EPA and included in my test kit.

  Some critics thought that extrapolating from miners to suburban neighborhoods was too big a leap. But in recent years the estimates have been supported by more extensive research on households. The most ambitious study was carried out in Iowa. The state has the highest average radon levels in the country. Women were chosen as subjects because they were more likely to spend time at home. To qualify they had to have occupied the same house for at least the past two decades. Radon detectors were placed in several locations in each house and readings were taken over the course of a year. Through questionnaires the researchers estimated the percentage of time the women spent in various rooms or other buildings—or outdoors, where average radon levels were also measured. When the women had been on vacations or business trips it was assumed that they received the average exposure for the United States. Allowances were made for occupational exposure, smoking (passive included), and other factors. In the end, it was concluded that someone living for fifteen years in a house with an average radon level of 4 picocuries per liter might have an “excess risk” of about 0.5. The age-adjusted incidence of lung cancer (for smokers and nonsmokers combined) is about 62 cases per 100,000 men and women per year. All things being equal, that would increase by half to 93 cases—31 more people suffering the horror of what is almost always a fatal condition.

  No single study can draw firm conclusions. The sample size is too small. But statisticians have gone on to amalgamate the data, producing what is called a pooled analysis. It’s tricky work. Research is conducted on different populations according to different methodologies. In combining the numbers these discrepancies must be accounted for. Three of the analyses—in Europe, North America, and China—found similar results to those derived from the experience with the miners, and most radon researchers now consider the matter clinched.

  But epidemiology is never a closed book. As I was anxiously poring over the radon literature I learned about a controversial hypothesis called hormesis, which holds that small doses of radiation are not just harmless but beneficial. We evolved in a world bathed in radiation, the argument goes, and have adapted to all but the most egregious assaults. A Johns Hopkins researcher recently concluded that levels of radon as high as 6.8 picocuries per liter may actually lower lung cancer risk. While the alpha particles are causing potentially carcinogenic mutations, low-level x-ray, gamma, and beta radiation may be activating epigenetic circuitry involved with DNA repair and apoptosis and enhancing the immune response. If that is true then reducing exposure to the EPA’s recommended action level might actually increase lung cancer risk. But that remains a maverick view. Considering the evidence on balance, I decided to start keeping a window cracked open when I work downstairs, even on cold days in winter. Just in case it matters.

  Not even the radiation from nuclear blasts, accidental or deliberate, has caused nearly as much cancer as most people think. Fifty workers were killed almost immediately by the estimated 100 million curies unleashed by the calamity at the Chernobyl nuclear power plant in 1986. A huge wave of cancer was expected to follow. But almost two decades later a United Nations study group lowered its estimate of the excess: 4,000 deaths among the 600,000 people (workers, evacuees, and nearby residents) who received the highest exposures, or less than 1 percent. There was an increase in thyroid cancer among people exposed as children, but the biggest public health problem, the report concluded, has been psychological. “People have developed a paralyzing fatalism because they think they are at much higher risk than they are, so that leads to things like drug and alcohol use, and unprotected sex and unemployment,” a researcher told The New York Times. The government of Ukraine recently opened the Chernobyl site to tourism, and ecologists have found that the absence of humans has turned the area into a mecca for wildlife.

  The nuclear warheads dropped on Hiroshima and Nagasaki in 1945 killed at least 150,000 people—either immediately from the impact or within months from injuries and radiation poisoning. Since then scientists have been monitoring the health of approximately 90,000 survivors. They estimate that radiation from the explosions has led to 527 excess deaths from solid cancers and 103 from leukemias.

  Tsutomu Yamaguchi survived both blasts. Visiting Hiroshima on a business trip, he was close enough to ground zero to suffer severe burns and a ruptured eardrum. After spending a night in a shelter, he returned home to Nagasaki in time for the second blast. He died in 2010 at age ninety-three. The cause was stomach cancer. It’s impossible to know how big a factor radiation played in the death of the old man, who had outlived so many others. Maybe the crowning blow was a diet of salted fish.

  It was leukemia that killed Marie Curie, the discoverer of radium (radon’s mother), at age sixty-six—“cancer in a molten, liquid form,” as Siddhartha Mukherjee memorably called it in The Emperor of All Maladies. When she was exhumed in 1995 for the honor of being reburied with Pierre in the Panthéon, French officials worried that her body would be dangerously radioactive. The three black notebooks describing her celebrated experiments are kept in a lead box at the Bibliothèque Nationale in Paris, and people who want to read them must sign a waiver acknowledging the risk. When her grave was opened her remains were found enclosed in a wooden coffin inside a lead coffin, which was inside another wooden coffin. Emanating from inside was 9.7 picocuries—almost twenty times less than the maximum considered safe for the public by the French government. Madame Curie was only half as hot as the air on that winter day in my office.

  With a half-life measured in centuries, the radium she had absorbed during her career would not have appreciably diminished since her death. France’s Office de Protection Contre les Rayonnements Ionisants therefore concluded that it probably wasn’t radium that killed her. A more likely cause of her cancer, they suggested, was the x-ray equipment she and her daughter, Irène Joliot-Curie, operated as medical volunteers in World War I. Irène, who won a Nobel Prize for her own work on radioactive elements, also died from leukemia. She was fifty-eight.

  For Pierre, death came early, at age forty-six, when he was run over on a Paris street by a horse-drawn carriage. We don’t know what kind of damage radium
might have done to his cells. He and Marie had both been too ill to travel to Stockholm to accept their Nobel Prize. Whether it was from radiation poisoning or physical exhaustion—extracting a gram of radium from a ton of pitchblende was like factory work—is unknown. Two years later they made the journey. In his Nobel lecture (also delivered on Marie’s behalf), Pierre described an experiment he had done on himself: “If one leaves a wooden or cardboard box containing a small glass ampulla with several centigrams of a radium salt in one’s pocket for a few hours, one will feel absolutely nothing. But fifteen days afterwards a redness will appear on the epidermis, and then a sore which will be very difficult to heal. A more prolonged action could lead to paralysis and death.” This destructiveness, he noted, had its uses. Radium was already being used to burn away tumors. So were x-rays, since just after their discovery in 1895. Long before it was established as a cause of cancer, radiation was used as a cure.

  Before Nancy’s chemo had ended her doctors began discussing the next stage of her treatment and what kind of particles they should use to irradiate her. Alpha particles are too massive and damaging to beam directly at the body. Beta rays, consisting of streams of electrons, are a gentler radiation. The lightweight particles penetrate a little deeper than alphas—it takes a sheet of aluminum to stop them—but they deliver less punch. They are often chosen to treat skin cancers, sparing what lies below. X-rays and gamma rays have the long reach needed for deeper cancers. Their wavelengths are so tiny that they can pass through many layers of tissue before striking their target. But their fuzzy edges make it harder to avoid harming nearby cells. Protons, which are 1,800 times heavier than electrons but smaller than alpha particles, can deliver large amounts of energy with less mess.