Thyroid Study Fails to Find Hanford Link

Scientists discern no increase in thyroid disease due to radiation releases

Karen Dorn Steele
Staff writer

RICHLAND -- A controversial study of Hanford's Cold War radiation releases has found no association between iodine-131 releases and increased thyroid disease in 3,440 people exposed as children.

The scientists behind the Hanford Thyroid Disease Study have spent another $1.5 million over the past three years to answer criticism of their work by the National Academy of Sciences. The study has cost taxpayers $19.5million.

In their final report released Friday, they say the conclusions they reached in their 1999 draft study still stand.

The study's findings don't mean that individuals living near Hanford weren't harmed by Hanford's invisible radiation clouds, said Dr. Thomas Hamilton, an endocrinologist and one of three lead scientists at the Fred Hutchinson Cancer Research Center.

"For this population under these conditions, we didn't see a relationship between iodine 131 and thyroid disease. That doesn't mean iodine 131 doesn't cause thyroid disease," Hamilton said.
"If there is an increased risk of thyroid disease, it is too small to observe," said Paul Garbe of the U.S. Centers for Disease Control and Prevention, which hired the Seattle team for the study.

Iodine 131 was released from Hanford's weapons plants in the 1940s and '50s. Winds carried it to vegetation eaten by cows and goats. It was passed on to the sensitive thyroid glands of children when they drank milk.

The 12-year study of people in seven Eastern Washington counties found 19 cases of thyroid cancer, 249 noncancerous thyroid nodules, 267 people with hypothyroidism or auto-immune disease and 34 with Graves Disease, which results in an overactive thyroid.

But the study team said the rates of thyroid disease in the Hanford downwinders is apparently no greater than those in the general population.

However, worldwide data on thyroid disease incidence are spotty, making that comparison less certain, according to a summary of their work.

The researchers identified more than 5,000 people who were born between 1940 and 1946 to mothers who lived in Benton, Franklin, Adams, Walla Walla, Okanogan, Ferry and Stevens counties.

They located 4,877 people, of whom 527 had died. Some 3,440 agreed to participate.

The participants were asked to provide detailed information about the food and milk they consumed and where they lived from 1944 to 1957, the years of the most significant Hanford releases.

They also attended a medical clinic, where they were examined for thyroid disease.

The study compared people thought to have received high radiation doses with others with smaller estimated doses, said Scott Davis, Fred Hutchinson's principal investigator.

If there had been a Hanford effect, they would have found more thyroid disease in the high-dose group. But they didn't, Davis said.

The study also found an unexplained higher-than-normal infant death rate among the group.

The deaths were from birth defects and problems late in pregnancy or in the first week after birth. But none of that increase was due to thyroid disease and some of the deaths occurred before Hanford's radioactive iodine releases began, Davis said.

In an interview Friday in Richland, the Fred Hutchinson team admitted it made mistakes during the release of the draft study in Richland in January 1999.

At that time, the study hadn't been peer-reviewed by the National Academy, which later faulted the scientists for exaggerating their main finding of no radiation effect and failing to disclose the study's uncertainties.

The NAS also said the study design was sound, but the way the results were communicated wasn't.
The study's release triggered an angry reaction from Hanford downwinders, who said they'd been dismissed and betrayed.

"We gave an impression that people didn't have thyroid disease, didn't suffer and weren't exposed," Hamilton said.

The scientists have tried to frame the issues differently in the final report.

"We've tried to consider more carefully what the (study's) limitations are," Davis said. "It's frustrating for people that epidemiology can't address an individual's disease," he said.

In response to the NAS critique, the CDC spent $340,000 for professional communications help from Ogilvie and Mather, a New York public relations firm. The CDC also convened "focus groups" in the Tri-Cities to discuss how to communicate the study results.

The scientists also devoted months to the NAS' scientific critiques, reviewing whether the study was statistically robust and checking possible underestimates of the radiation does.

They also reviewed the dietary information on what downwinders consumed as children that was used to help estimate their radiation doses.

Due to the extensive NAS critique, the study's peer review was "much more thorough" than is typical, Garbe said.

The government study was mandated by Congress after Hanford officials admitted for the first time in 1986 that they had released substantial amounts of radiation while making plutonium for nuclear bombs.

It was the first to locate and examine people living in the path of radiation emissions from a U.S. weapons production site.

Other civilians who have been studied include Japanese atomic bomb survivors at Hiroshima and Nagasaki; residents of the Marshall Islands exposed to H-bomb tests; Utah schoolchildren showered with fallout from nuclear bomb tests in Nevada; and Ukrainian children following the 1986 explosion of the Chernobyl nuclear reactor.

A link between iodine 131 and thyroid disease has been found in those studies, where people were exposed to a mix of internal and external radiation.

Hamilton, who studied radiation damage to residents of the Marshall Islands, said in 1999 that he was shocked the Hanford study hadn't detected a radiation effect.

The study team carefully reviewed its work to see whether they'd missed a dose response, Hamilton said this week.

Hanford's releases were different from the other sites studied worldwide, he said. At Hanford, the radiation doses were exclusively from iodine 131, were smaller, and the exposure was more drawn out, he said.

"It was probably for that reason we didn't find thyroid disease," he said.

The study results can be seen on the CDC Web site at

Karen Dorn Steele can be reached at (509) 459-5462, or by e-mail at