I must admit to being perplexed when I see sentences in news stories like: “TEPCO vice-president Sakae Muto said, however, the plutonium 238, 239 and 240 collected were not in concentrations harmful to human health.”
While I am far from being an expert, it seems to me like at least some of the discussion of the risks from radiation is misleading. In particular, I think it is a bit misleading to pretend that radiation is a homogenous mass like a magnetic field. In reality, the radionucleotides that have been released from Fukushima are solids and gases getting blown around in the wind. They are less like the fading signal from a cell phone tower as you walk away, and more like a person’s ashes that have been scattered into the wind. You can take an average measure for the amount of radiation in an area, but that doesn’t give you a good sense of how much exposure a person will get if they inhale or ingest a random batch of windswept particles.
This seems especially true when it comes to plutonium. Imagine a little speck of plutonium that was part of a burning MOX fuel rod in the Number 3 reactor at Fukushima. Burning zircaloy cladding on the fuel rods could have shifted it into a puff of radioactive smoke that either escaped through a crack in the reactor’s containment or was intentionally vented as part of ongoing efforts to cool the reactors. If that little speck ends up in your lung, it certainly seems as though it would be a danger to your health.
Am I totally off base here?
Yes, actually, you are.
Because the amount does matter. Concentrations are absolutely essential to determining the effects of radioactive particles.
Can you elaborate a bit?
I realize that when it comes to radiation sickness, total dose per unit time (which can be measured in Sieverts) is what matters most.
But what about long-term health issues? Doesn’t having even a tiny speck of plutonium lodged in your lung pose a significant health risk?
Last week, the Institute for Energy and Environmental Research, an independent think tank in the United States, said that since the quake and its aftermath, the plant has already released far more radioactivity than the 1979 Three Mile Island accident. The institute, based in Takoma Park, Maryland, said that by March 22, the Fukushima reactors had released about 2.4 million curies of iodine 131, about 160,000 times the best estimate of the amount released at Three Mile Island, and about 10 percent of the amount released in Chernobyl in 1986. Fukushima Daiichi has also released half-a-million curies of cesium-134 and cesium-137, which have longer half lives, also about 10 percent the amount released in Chernobyl.
A Layman’s Intro to Radiation
Updated 3/24 — added discussion of inhaled/ingested radionuclides at bottom.
Unsafe at Any Dose
By HELEN CALDICOTT
Published: April 30, 2011
SIX weeks ago, when I first heard about the reactor damage at the Fukushima Daiichi plant in Japan, I knew the prognosis: If any of the containment vessels or fuel pools exploded, it would mean millions of new cases of cancer in the Northern Hemisphere.
Many advocates of nuclear power would deny this. During the 25th anniversary last week of the Chernobyl disaster, some commentators asserted that few people died in the aftermath, and that there have been relatively few genetic abnormalities in survivors’ offspring. It’s an easy leap from there to arguments about the safety of nuclear energy compared to alternatives like coal, and optimistic predictions about the health of the people living near Fukushima.
But this is dangerously ill informed and short-sighted; if anyone knows better, it’s doctors like me. There’s great debate about the number of fatalities following Chernobyl; the International Atomic Energy Agency has predicted that there will be only about 4,000 deaths from cancer, but a 2009 report published by the New York Academy of Sciences says that almost one million people have already perished from cancer and other diseases. The high doses of radiation caused so many miscarriages that we will never know the number of genetically damaged fetuses that did not come to term. (And both Belarus and Ukraine have group homes full of deformed children.)
“Doctors understand these dangers. We work hard to try to save the life of a child dying of leukemia. We work hard to try to save the life of a woman dying of metastatic breast cancer. And yet the medical dictum says that for incurable diseases, the only recourse is prevention. There’s no group better prepared than doctors to stand up to the physicists of the nuclear industry.
Still, physicists talk convincingly about “permissible doses” of radiation. They consistently ignore internal emitters — radioactive elements from nuclear power plants or weapons tests that are ingested or inhaled into the body, giving very high doses to small volumes of cells. They focus instead on generally less harmful external radiation from sources outside the body, whether from isotopes emitted from nuclear power plants, medical X-rays, cosmic radiation or background radiation that is naturally present in our environment.
However, doctors know that there is no such thing as a safe dose of radiation, and that radiation is cumulative. The mutations caused in cells by this radiation are generally deleterious. We all carry several hundred genes for disease: cystic fibrosis, diabetes, phenylketonuria, muscular dystrophy. There are now more than 2,600 genetic diseases on record, any one of which may be caused by a radiation-induced mutation, and many of which we’re bound to see more of, because we are artificially increasing background levels of radiation.”
Mr. Suzuki and others say the risks are not as high as some people fear. But they admit that there is a lack of hard data about the health effects of lower radiation doses delivered over extended periods. Most knowledge about radiation’s health effects comes from Japan and studies on the survivors of the atomic bombs in Hiroshima and Nagasaki. Researchers calculated the exposure levels of survivors and then waited for decades to see what they died from.
They then compared the data with death rates and causes of death in other, unexposed parts of Japan.
The results showed elevated cancer rates from high levels of radiation released during atomic blasts, said Mr. Nagataki, who did such studies. But researchers are left to rely on educated guesses in trying to extrapolate those results down to lower doses, he said.
Mr. Nagataki and other experts agreed that whatever additional cancer stemmed from the radiation levels seen in many of the evacuation zones around the Fukushima plant would probably be very low, even if residents remained in them. They said that a dose of 20 millisieverts per year would likely raise the rate of cancer deaths by far less than one percent, though the radiation levels in some of the evacuated areas are much higher than that, especially near the plant.
http://www.nytimes.com/2011/05/02/world/asia/02japan.html
Japanese Find Radioactivity on Their Own
IWAKI, Japan — Kiyoko Okoshi had a simple goal when she spent about $625 for a dosimeter: she missed her daughter and grandsons and wanted them to come home.
Local officials kept telling her that their remote village was safe, even though it was less than 20 miles from the crippled Fukushima Daiichi nuclear power plant. But her daughter remained dubious, especially since no one from the government had taken radiation readings near their home.
So starting in April, Mrs. Okoshi began using her dosimeter to check nearby forest roads and rice paddies. What she found was startling. Near one sewage ditch, the meter beeped wildly, and the screen read 67 microsieverts per hour, a potentially harmful level. Mrs. Okoshi and a cousin who lives nearby worked up the courage to confront elected officials, who did not respond, confirming their worry that the government was not doing its job.
With her simple yet bold act, Mrs. Okoshi joined the small but growing number of Japanese who have decided to step in as the government fumbles its reaction to the widespread contamination, which leaders acknowledge is much worse than originally announced. Some mothers as far away as Tokyo, 150 miles to the south of the plant, have begun testing for radioactive materials. And when radiation specialists recently offered a seminar in Tokyo on using dosimeters, more than 250 people showed up, forcing organizers to turn some people away.
“Roentgen, rad, and rem are roughly comparable measures of radiation. A whole-body exposure of 20-100 rem will result in a temporary reduction in white blood cells; of 100-200 rem, vomiting, diarrhea, fatigue, and reduction in resistance to infection; of 200-300 rem, serious radiation sickness with symptoms as with 100-200 rem and 10 to 35 percent mortality in thirty days; of 300-400 rem, serious radiation sickness, destruction of bone marrow and gastrointestinal tissue, and 50 to 70 percent mortality in thirty days; of 400-1,000 rem, acute illness and 60 to 95 percent mortality in thirty days. Above 1,000 rem, 100 percent of the victims will die within days. (Source: The Atomic Archive.)”
Rhodes, Richard. Arsenals of Folly: The Making of the Nuclear Arms Race. p. 9