The Unexpectedly Loose Connection Between Radioactivity and Cancer

By George Johnson | October 22, 2013 10:01 am

In an op-ed piece today in the New York Times, David Ropeik writes about how people’s fears of radiation often overshadow its  dangers.

Our anxiety about nuclear radiation is rooted in our understandable fear of the terrible power of nuclear weapons. But in the 68 years since those weapons were first used in anger, we have learned, from the survivors of Hiroshima and Nagasaki themselves, that ionizing radiation — the type created by a nuclear reaction — is not nearly the powerful carcinogen or genetic mutagen that we thought it was.

In the days after Fukushima, I explored this disconnect in an essay for the Sunday Times called Radiation’s Enduring Afterglow. (Gravity killed more people by far than the nuclear forces.) I was just beginning the research for my book, The Cancer Chronicles, and I ended up writing a chapter, “Gambling With Radiation,” which describes some of the surprising things I learned. After more than half a century of monitoring the health of about 90,000 survivors of Hiroshima and Nagasaki, scientists estimate that radiation from the explosions is responsible for a total of 527 excess deaths from solid cancers and 103 from leukemias — a fraction of what I would have supposed.

In the chapter I describe the story of Tsutomu Yamaguchi, who lived to tell his children about witnessing both mushroom clouds.

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.

The steady consumption of foods laced with salt is one explanation for why stomach cancer remains stubbornly prevalent in Japan, while it has receded in other developed countries. But whatever the cause, Mr. Yamaguchi lived a long, good life.

When I was a boy my dad gave me several pieces of Trinitite — green, glassy chunks of sand melted into rock by the heat of the first atomic explosion in southern New Mexico, the trial that preceded the bombings in Japan. (How weirdly coincidental that one of the atomic spies in World War II, the brother of Ethel Rosenberg, was named David Greenglass.) Trinitite — I still have it in a wooden box — is mildly radioactive but not worth worrying about.

No one disputes that in high enough doses ionizing radiation is carcinogenic. It breaks molecular bonds, adding to the number of genetic mutations that normally occur as cells divide. That raises the odds that, somewhere along the way, a cell will acquire the rare combination that can start a cancer. It’s like winning Shirley Jackson’s Lottery.

But when you consider the legacy of Hiroshima and Nagasaki, it doesn’t make sense to worry about the minuscule exposures from dental x-rays or from living on the other side of the planet from Fukushima — or even right in Fukushima prefecture. For all the horrible consequences of the meltdown, cancer is among the least of the threats. But neighbors who do get cancer, even at a very old age, will naturally suspect that it was because of Fukushima. The brain demands that there be a cause for every effect.

It is impossible to understand the phenomenon of cancer without breaking free from the notion that every case can be linked to a carcinogen, to something that can be blamed. The causes are subtler and more devious — and so much more interesting.

Cancer is an inevitable, unfortunate byproduct of multicellularity, a built-in fact of evolution. Cells, these components of our bodies, must be free to innovate or we never would have evolved. Sometimes they will stumble in their explorations into dangerous territory. Sometimes, but not often, there will be something we can do to stop runaway growth or at least slow it down. But cancer is not a disease like polio or smallpox or tuberculosis that can be traced to a single agent — or even a handful of agents — and diligently wiped away. If only it were so simple. If only there really was a war to win, and not just endless, indistinct battles.


Related posts: The Most Powerful Carcinogen is Entropy

The Cancer from Fukushima and Hiroshima


Comments are welcome by email. For public discussion please use Twitter.

For a glimpse of my new book, The Cancer Chronicles, including the table of contents and index, please see this website.


MORE ABOUT: Cancer, Fukushima, Hiroshima
  • John H.

    It has been a long time since I read you George. My mistake, to be corrected. This article reminds me of a study of wildlife in Chernobyl region. After the accident the wildlife returned and did well, this in spite of obvious but subtle radiation effects. The study concluded that human occupation was more dangerous to the wildlife than the radiation. This misanthrope finds some pleasure in that conclusion. :)
    I have previously noted that that atom bombs did not produce anywhere near the expected cancer rates; though thyroid cancer could be the exception (fortunately very treatable) and thyroid cancer rates have risen in many countries. There may even be a hormetic effect from low dose radiation. If the radiation from dental x-rays is a problem it should have become glaringly obvious by now.
    With the exception of smoking, the best way to avoid cancer is to die young.


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Whether a subtle new pattern shows up in an experiment on the Higgs boson, an epidemiological report about a suspected cancer cluster, or a double-blind trial purporting to demonstrate ESP, it can be maddeningly difficult to distinguish between what we see and what we think we see. "Fire in the Mind" takes a look at the big questions behind today’s science news.

About George Johnson

George Johnson writes about science for the New York Times, National Geographic Magazine, Slate, and other publications. His nine books include The Cancer Chronicles: Unlocking Medicine's Deepest Mystery (August 2013), The Ten Most Beautiful Experiments, A Shortcut Through Time, and Fire in the Mind. He is a winner of the AAAS Science Journalism Award and has twice been a finalist for the Royal Society science book prize. Co-founder and director of the Santa Fe Science Writing Workshop, he can be found on the Web at Twitter @byGeorgeJohnson.


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