Five years ago, the Fukushima nuclear power plant disaster spread deadly radiation by land and by sea. In the years since, Japan and the rest of the world have learned many lessons about why the reactor failed and how to
Five years ago, the Fukushima nuclear power plant disaster spread deadly radiation by land and by sea. In the years since, Japan and the rest of the world have learned many lessons about why the reactor failed and how to prevent another such catastrophe.
But one of the most intriguing lessons of Fukushima involves hundreds of thousands of Japanese children potentially exposed to excessive radiation.
Japanese public health officials were aware of an increased incidence of thyroid cancer in Russian children after the 1986 Chernobyl nuclear accident. So researchers screened more than 300,000 Fukushima-area children 18 and younger for thyroid irregularities that could turn into cancer.
The scientists’ initial findings set off alarms. Tests detected some 30 times more cases of early thyroid cancer in Fukushima children than in children elsewhere in Japan who weren’t exposed to the reactor radiation. Many children underwent biopsies, and some even had their thyroid glands removed, a procedure that carries risks and means a child must take thyroid pills for the rest of his or her life.
But a follow-up dive into the data led many epidemiologists to doubt those early findings for several reasons:
• Children living closer to the accident in areas of greatest contamination had no greater rate of early cancer than those living farther away.
• Younger children and infants, whose thyroids are more likely to be affected than those of older children, did not show an expected higher rate of abnormal findings.
• Some cancers were observed less than a year after the meltdown. It generally takes years for thyroid cancer to develop after radiation exposure.
The epidemiologists’ explanation: The cancer findings weren’t largely attributable to the increased radiation risk, but instead occurred because tens of thousands more children were screened for thyroid cancer using sensitive ultrasound devices. Typically, those children would not have been screened and the abnormalities wouldn’t have been found. …
Thyroid cancer is a rare disease and usually develops slowly. Many of the ultrasound findings in the Fukushima children might never progress to full-blown cancer. An epidemic of childhood thyroid cancer deaths tied to the reactor meltdown is unlikely. Some of the children whose thyroid glands were removed might have been better off had they been placed under long-term medical observation instead.
The message to all patients who are contemplating health screenings: Testing can save lives. But it can also lead to overdiagnosis and, most damaging, overtreatment. Ask your doctor because sometimes what you don’t know might not hurt you. What you do know might.
— Chicago Tribune
