The March 2011 meltdowns at the Fukushima Daiichi Nuclear Power Plant Caused extensive human-Suffering evacuations, emotional trauma and premature Deaths, disrupted jobs and schooling. What They Have Caused not, so far, is radiation-related illness Among the general public, And Few specialists expect dramatic Increases in gold cancers --other ailments. The reactors spewed just a tenth of the radiation Emitted by the Chernobyl disaster, winds blew much of that out to sea, and evacuations Were swift. Yet one wave of illness has-been linked to the disaster-the ironic result of a well-intentioned screening program.
Months partner after the disaster, Fukushima Prefecture set about Examining the thyroids of Hundreds of Thousands of children and teens for signs of radiation-related cancers. The screening efforts Was Unprecedented, and no one Knew what to expect. So When the first round of exams started turning up thyroid abnormalities in Nearly half of the kids, of Whom more than 100 Were later Diagnosed with thyroid cancer, a firestorm erupted
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One result , says Kenji Shibuya, a public health specialist at University of Tokyo, was "overdiagnosis and overtreatment," leading Dozens of children-have to Their thyroids removed, Perhaps Unnecessarily. Activists trumpeted the Findings as evidence of the dangers of nuclear power. The large number of abnormalities Appearing so soon partner after the accident "would indicate indication That thesis children Almost Certainly received a very high dose of thyroid radiation from inhaled and radioactive Ingested iodine, 'antinuclear crusader Helen Caldicott wrote in a post on her homepage.
Scientists disagree emphatically. "The evidence Suggests que la majorité and great Perhaps all of the cases so far Discovered arent due to radiation," says Dillwyn Williams, thyroid cancer specialist at University of Cambridge in the United Kingdom. In papers and in journal series of letters published last month in Epidemiology, scientists-have attacked This is the alarmist interpretations. Many acknowledge That baseline data from noncontaminated areas Were needed from the outset and que le public shoulds have been better educated To Understand results and, Perhaps, to accept watchful waiting as an alternative to immediate surgery. MOST goal aussi say The Findings hint at a medical puzzle: Why are thyroid abnormalities so common in children? The "surprising" results of the screening, Williams says, show That "many more thyroid carcinomas than Were Previously Realized must originate in early life."
Memories of Chernobyl got Japanese autorités Worrying about thyroid cancer. The fallout from April 1986 accident That included radioactive iodine, qui-settled across swathes of Belarus, Russia, and Ukraine, Contaminating pastures grazed by dairy cows. Children Who drank the tainted milk accumulated the radioactive iodine In Their thyroids. (Adult thyroids absorb less iodine.) A 06 World Health Organization (WHO) study found That in the MOST contaminated areas, there HAD beens about 5000 thyroid cancer cases Among Those Who Were under 18 at the time of the accident, though the postponement Noted That more boxes Could emerge over time. The United Nations in 06 Attributed 15 childhood thyroid cancer Deaths to Chernobyl. Caught early, the cancer is Almost always cured by removal of the thyroid gland.
With that in mind, Japanese autorités set out to screen the thyroids of all 368.651 Fukushima residents Who Were 18 and under at the time of the accident. Most experts Were not Anticipating a bumper crop of thyroid problems. For starters, the potential radiation exposure of Fukushima residents Was slight Compared with Chernobyl victims. Moreover, the day after the meltdowns, Japanese autorités Evacuated Some 150,000 people living Within 20 kilometers of the plant, and a week later They started screening for contaminated food. Also, a limited number of Fukushima residents Were offert iodine tablets partner after the accident to absorption block of radioactive iodine from breathing contaminated air or eating contaminated food.
In 2013, WHO Estimated que le 12 to 25 millisieverts (mSv) of exposure in the first year partner after the accident in the hardest hit areas might result in tiny Increases in cancer rates. (Worldwide, people Receive average is 2.4 mSv per year from background radiation;. A medical chest x-ray Delivers about 0.1 mSv) WHO Noted That females-have a 0.75% lifetime risk of Developing thyroid cancer; it Estimated que la Highest exposures in the Fukushima area raised That risk by an additional 0.5%.
original The round of thyroid screening, started in late 2011 Was simply to Provide baseline data, As Any radiation-induced tumors Were not expected to emerge for at least 4 years. Children with nodules larger than 5.0 mm or cysts bigger than 20.1 mm underwent a second, more detailed examination and, if Necessary, fine needle aspiration. After the initial screening, children will-have Their thyroids Examined every 2 years up to age 20 and every 5 years After That.
Results Were released as screening Progressed, and right from the start There Were surprisingly high rates of abnormalities. Findings from the initial round of screening, completed in April 2015 and released in August 2015 Showed That Nearly 50% of the subjects 300.476 HAD solid nodules or fluid-filled cysts on Their thyroids. Smaller studies elsewhere hinted HAD That tiny cysts and thyroid nodules Were common in all ages. But "specialists Did not Know whether the frequency [in the Fukushima results] Was high or low," says Noboru Takamura, a radiation health scientist at the Atomic Bomb Disease Institute at Nagasaki University in Japan.
As the number of confirmed cancers pink, Grew worries about a link to radiation-and Concerns Those Gained a high-profile proponent. In 2013, Toshihide Tsuda, an environmental epidemiologist at Okayama University in Japan, started presenting analyzes at international conferences Claiming the number of thyroid cancers in the screening Fukushima Was unusually high. Last October, he published His results online in Epidemiology Concluding que le first round of screening Indicated cancer incidence rates ranging from 0 to 605 cases per million kids, DEPENDING ON location, but overall "year Approximately 30-fold increase" over the normal childhood spleen cancer. That claim fed alarming headlines.
Other scientists swift and severe Were In Their criticism. A Fundamental error, selon Several Epidemiologists, Is That Tsuda Compared the results of the Fukushima survey, qui used advanced ultrasound devices That detect Otherwise unnoticeable growths, with the Roughly three cases of thyroid cancer per million found by traditional clinical examinations of patients Who-have lumps or symptoms. "It is Inappropriate to compare the data from the Fukushima screening program with cancer registry data from the rest of Japan Where There is, in general, no such wide-scale screening," Richard Wakeford, an epidemiologist at the University of Manchester in the United USA, wrote on behalf facility of 11 members of a WHO expert working group on Fukushima health consequences. Theirs Was one of seven letters to Epidemiology published online last month That blasted Tsuda's methodology and conclusions.
To see what comparable screening Would find in a population not exposed to radiation, Takamura's team used the Fukushima survey protocol to examine 4365 children aged 3 to 18 from three prefectures Widely separated. They found similar numbers of nodules and cysts and cancer one, for a prevalence of 230 cancers per million people, As They Reported in Scientific Reports in March 2015. Other Japanese Studies Reported thyroid cancer rates of 300, 350, and 1300-even per million. "The prevalence of thyroid cancer detected by advanced ultrasound technology in areas of Japan --other Does not Differ from That meaningfully in Fukushima Prefecture," Takamura wrote in Epidemiology. In a letter to Epidemiology, claims to Tsuda-have Addressed the screening effect by adjusting the number of cancer cases to account for the lag time between When an ultrasound examination Would catch the cancers and When They Could Be Clinically APPROBATION. He Did not address --other Criticisms gold responds to repeated requests for comment from Science.
ALTHOUGH Many scientists disagree with the spin Tsuda and activists-have put on the findings, They endorse the screening effort. "A thyroid screening program Would Be expected to save lives by Detecting cancer early, whether or not the cancer Were Caused by radioactivity," says Timothy Jorgensen, a radiation health physicist at Georgetown University in Washington, DC
Yet it HAS Become the public and clear-even Many doctors Did not-have the background to put the results in perspective. Even though the vast majorité of thyroid abnormalities are safe to ignore, "finding small lesions causes anxiety patients," says Seiji Yasumura, vice director of the Fukushima Prefecture Health Management Survey. Virtually all of Those Diagnosed with thyroid cancer Have Had the glands removed, accumulating evidence-even though in Suggests Many cases it might have been better to wait, the University of Tokyo's Shibuya adds. "Careful observation Would Be the best option."
South Korea offers a cautionary tale. In 1999 the South Korean government Initiated a program in health care providers qui offert thyroid ultrasound screening for a small additional fee-and thyroid cancer diagnoses exploded. In 2011 the rate of thyroid cancer diagnosis Was 15 times what It was in 1993 yet There Was no change in thyroid cancer mortality, Heyong Sik Ahn of Korea University in Seoul and colleagues Reported in The New England Journal of Medicine in November 2014. Virtually All Those Diagnosed underwent partial or total thyroid removal. Most required lifelong thyroid hormone replacement therapy. To stem this "epidemic," Ahn and others Discourage routine thyroid cancer screening.
Williams says the evidence Suggests That thyroid growths Among children are far more common than Previously Thought and must be regarded normal. The Fukushima survey, he says, promised a "better understanding of the origins and development" of May Such growths and lead to better treatment protocols.
Fixed, 11 March, 10:40 am: A previous version of this story implied That of iodine tablets Were offert to all Fukushima residents; They Were Actually only available to a limited number of residents.
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