Plagues,
Pestilences and Diseases
Japan: Future cancers from Fukushima Nuclear plant to linger
for a century
By Malcolm Ritter and Mari Yamaguchi
Associated Press / November 21, 2011
FUKUSHIMA, Japan—Even if the worst nuclear accident in 25 years
leads to many people developing cancer, we may never find out.
Looking back on those early days of radiation horror, that may
sound implausible.
But the ordinary rate of cancer is so high, and our understanding
of the effects of radiation exposure so limited, that any increase
in cases from the Fukushima nuclear plant disaster may be
undetectable.
Several experts inside and outside Japan told The Associated Press
that cancers caused by the radiation may be too few to show up in
large population studies, like the long-term survey just getting
under way in Fukushima.
That could mean thousands of cancers under the radar in a study of
millions of people, or it could be virtually none. Some of the
dozen experts the AP interviewed said they believe radiation doses
most Japanese people have gotten fall in a "low-dose" range, where
the effect on cancer remains unclear.
The cancer risk may be absent, or just too small to detect, said
Dr. Fred Mettler, a radiologist who led an international study of
health effects from the 1986 Chernobyl disaster.
That's partly because cancer is one of the top killers of people
in industrialized nations. Odds are high that if you live long
enough, you will die of cancer. The average lifetime cancer risk
is about 40 percent.
In any case, the 2 million residents of Fukushima Prefecture,
targeted in the new, 30-year survey, probably got too little
radiation to have a noticeable effect on cancer rates, said Seiji
Yasumura of the state-run Fukushima Medical University. Yasumura
is helping run the project.
"I think he's right," as long as authorities limit children's
future exposure to the radiation, said Richard Wakeford, a
visiting epidemiology professor at the Dalton Nuclear Institute at
the University of Manchester in England. Wakeford, who's also
editor of the Journal of Radiological Protection, said he's
assuming that the encouraging data he's seen on the risk for
thyroid cancer is correct.
The idea that Fukushima-related cancers may go undetected gives no
comfort to Edwin Lyman, a physicist and senior scientist with the
Union of Concerned Scientists, a group that advocates for nuclear
safety. He said that even if cancers don't turn up in population
studies, that "doesn't mean the cancers aren't there, and it
doesn't mean it doesn't matter."
"I think that a prediction of thousands of cancer deaths as a
result of the radiation from Fukushima is not out of line," Lyman
said. But he stressed that authorities can do a lot to limit the
toll by reducing future exposure to the radiation. That could mean
expensive decontamination projects, large areas of condemned land
and people never returning home, he said. "There's some difficult
choices ahead."
Japan's Cabinet this month endorsed a plan to cut contamination
levels in half within the next two years.
The plant was damaged March 11 by a tsunami triggered by a
magnitude-9 earthquake. Japanese authorities estimate it leaked
about one-sixth as much radiation as the Chernobyl accident. It
spewed radioactive materials like iodine-131, cesium-137 and 29
others contaminating the water, soil, forests and crops for miles
around.
So far, no radiation-linked death or sickness has been reported in
either citizens or workers who are shutting down the plant.
But while the Fukushima disaster has faded from world headlines,
many Japanese remain concerned about their long-term health. And
many don't trust reassurances from government scientists like
Yasumura, of the Fukushima survey.
Many consumers worry about the safety of food from Fukushima and
surrounding prefectures, although produce and fish found to be
above government-set limits for contamination have been barred
from the market.
Fukushima has distributed radiation monitors to 280,000 children
at its elementary and junior high schools. Many children are
allowed to play outside only two or three hours a day. Schools
have removed topsoil on the playgrounds to reduce the dose, and
the Education Ministry provided radiation handbooks for teachers.
Thousands of children have been moved out of Fukushima since the
March disasters, mainly due to radiation fears.
Many parents and concerned citizens in and around Fukushima, some
even as far as Tokyo, carry Geiger counters for daily measurement
of radiation levels in their neighborhoods, especially near
schools and kindergartens. The devices are probably one of the
most popular electronics gadgets across Japan these days. People
can rent them at DVD shops or drug stores in Fukushima.
. Some people are turning to traditional Japanese diet -- pickled
plum, miso soup and brown rice -- based on a belief that it boosts
the immune system.
"I try what I believe is the best, because I don't trust the
government anymore," says Chieko Shiina, who has turned to that
diet. The 65-year-old Fukushima farmer had to close a small
Japanese-style inn due to the nuclear crisis.
She thinks leaving Fukushima would be safer but says there is
nowhere else to go.
"I know we continue to be irradiated, even right at this moment. I
know it would be best just to leave Fukushima," she said.
Yuka Saito, a mother of four who lives in a Fukushima neighborhood
where the evacuation order was recently lifted, said she and her
three youngest children spent the summer in Hokkaido to get away
from the radiation. She tells her children, ages 6 to 15, to wear
medical masks, long-sleeved shirts and a hat whenever they go out,
and not to play outside.
She still avoids drinking tap water and keeps a daily log of her
own radiation monitoring around the house, kindergarten and
schools her children attend.
"We Fukushima people are exposed to radiation more than anyone
else outside the prefecture, but we just have to do our best to
cope," she said. "We cannot stay inside the house forever."
Japanese officials say mental health problems caused by excessive
fear of radiation are prevalent and posing a bigger problem than
actual risk of cancer caused by radiation.
But what kind of cancer risks do the Japanese really face?
Information on actual radiation exposures for individuals is
scarce, and some experts say they can't draw any conclusions yet
about risk to the population.
But Michiaki Kai, professor of environmental health at Oita
University of Nursing and Health Sciences, said that based on
tests he's seen on people and their exposure levels, nobody in
Fukushima except for some plant workers has been exposed to
harmful levels of radiation.
Radiation generally raises cancer risk in proportion to its
amount. At low-dose exposures, many experts and `regulators
embrace the idea that this still holds true. But other experts say
direct evidence for that is lacking, and that it's not clear
whether such small doses raise cancer risk at all.
"Nobody knows the answer to that question," says Mettler, an
emeritus professor of radiology at the University of New Mexico
and the U.S. representative to the United Nations Scientific
Committee on the Effects of Atomic Radiation, or UNSCEAR. If such
low doses do produce cancers, they'd be too few to be detected
against the backdrop of normal cancer rates, he said.
To an individual the question may have little meaning, since it
deals with the difference between no risk and small risk. For
example, the general population was told to evacuate areas that
would expose them to more than 20 millisieverts a year. A
millisievert measures radiation dose and 20 mSv is about seven
times the average dose of background radiation Americans get in a
year. A child exposed to 20 mSv for a year would face a calculated
risk of about 1 in 400 of getting cancer someday as a result, says
David Brenner of Columbia University. So that would add 0.25
percent onto the typical lifetime cancer risk of about 40 percent,
he said.
Brenner stresses that such calculations are uncertain because
scientists know so little about the effects of such small doses of
radiation.
But in assessing the Fukushima disaster's effect on populations,
the low-dose question leads to another: If a lot of people are
each exposed to a low dose, can you basically multiply their
individual calculated risks to forecast a number of cancers in the
population?
Brenner thinks so, which is why he believes some cancers might
even appear in Tokyo although each resident's risk is "pretty
minuscule."
But Wolfgang Weiss, who chairs the UNSCEAR radiation committee,
said the committee considers it inappropriate to predict a certain
number of cancer cases from a low-dose exposure, because low-dose
risk isn't proven.
Nuclear accidents can cause cancer of the thyroid gland, which can
absorb radioactive iodine and become cancerous. That disease is
highly treatable and rarely fatal.
After the Chernobyl disaster, some 6,000 children exposed to
radioactive fallout later developed thyroid cancer. Experts blame
contaminated milk. But the thyroid threat was apparently reduced
in Japan, where authorities closely monitored dairy radiation
levels, and children are not big milk drinkers anyway.
Still, the new Fukushima survey will check the thyroids of some
360,000 young people under age 18, with follow-ups planned every
five years throughout their lifetimes.
But the survey organizers are having trouble getting responses,
partly because of address changes. As of mid-October, less than
half the residents had responded to the health questionnaire.
Some residents are skeptical about the survey's objectivity
because of mistrust toward the government, which repeatedly
delayed disclosing key data and which revised evacuation zones and
safety standards after the accident. Some wonder if the study is
using them as human guinea pigs to examine the impact of radiation
on humans.
Eisuke Matsui, a lung cancer specialist and a former associate
professor at Gifu University School of Medicine, criticized the
project. He said it appears to largely ignore potential
radiation-induced health risks like diabetes, cataracts and heart
problems that have been hinted at by some studies of Chernobyl.
"If thyroid cancer is virtually the only abnormality on which they
are focusing, I must say there is a big question mark over the
reliability of this survey," he said.
"We should check as many potential problems as possible," Matsui
said.
Yasumura acknowledges the main purpose of his study is "to relieve
radiation fears." But Matsui says he has a problem with that.
"A health survey should be a start," Matsui says, "not a goal."
------
Science Writer Malcolm Ritter reported from New York.