By Mary L. Grady

More than 50 years after toxic radioactive substances were released into the sky over Eastern Washington, a public health project headed by Capt. Greg Thomas of the U.S. Public Health Service, is nearly over. Another chapter in the troubled nuclear fuels industry in the United States has ended with the results of a study calling a link between thyroid disease and exposure to radiation “unsubstantiated.”

However, a legacy wrought by government secrecy and scientific uncertainty remains.

Exposure to radiation has been linked to increased risk of thyroid neoplasia in studies of catastrophic radiation releases such as the bombings of Japan in 1945. Despite that and other studies measuring thyroid disease resulting from radioactive fallout, the links and mechanisms between radiation and public health are poorly understood.

According to public health agencies, about 2 million people were exposed either through the radiation released into air or into the water between 1940 and 1972 from the Hanford Nuclear Reservation in southwestern Washington State. Scientists with the Centers for Disease Control estimate that at least half of those exposed still live in Washington state. More than a few live on Mercer Island, said Thomas, an Islander himself.

These people are called “Downwinders,” after the katabatic desert winds that spread the radiation cross the arid landscape to the west.

Individuals born between 1940 and 1951, or who lived in the area as small children, in the counties around Hanford, primarily Benton, Franklin and Adams counties, were exposed to radioactive iodine and are considered most at risk.

They were exposed to radioactive toxins that were a byproduct of the weapons-grade plutonium manufactured at Hanford. The most dangerous byproduct was radioiodine, or iodine 131, which concentrates in the thyroid gland in humans.

In 1943, the federal government had selected Hanford as the site for the world’s first large-scale nuclear fuels production plant. Hanford produced the plutonium for the bomb dropped on Nagasaki, Japan, during World War II.

Thomas has headed up the public health outreach effort for the region, called the Hanford Community Health Project (HCHP). Working in tandem with the Environmental Protection Agency, the focus of the agency is on the human health issues for those exposed to contaminants from Superfund sites such as Hanford.

Thomas is overseeing the last efforts to educate the public, still concerned, he said, about the long term effects of exposure to iodine 131. The project money is gone, but worries about possible ill effects are probably not.

Hanford’s airborne radiation was not just limited to the immediate area around the nuclear reservation. It spread throughout Eastern Washington, northeastern Oregon, and into northern Idaho, Montana and Canada. Food grown on contaminated farm fields and milk from cows that grazed there transferred the radiation to people.

“The people who lived in this area during this time do have an additional risk factor for thyroid cancer, in particular if they were children during the time of the releases,” Thomas explained.

But it is clear that there is no certain answer to the question of long-term risk to exposure to radiation released at Hanford.

A final report on the incidence of thyroid disease in people exposed to radioactive iodine releases from Hanford was published in the Dec. 1, 2004, issue of the Journal of the American Medical Association (JAMA). A study that tracked nearly 3,500 people from the region, conducted by the Fred Hutchinson Cancer Research Center, concluded that the statistical evidence does not support the hypothesis that exposure to radiation from Hanford increased the risk of thyroid diseases.

It is a perplexing outcome.

Researchers don’t really know the difference between the effects of long-term exposure versus catastrophic events like Chernobyl, Nagasaki and Hiroshima in 1945 or fallout from the nuclear bomb tests in the Marshall Islands, Thomas explained. Scientists also aren’t clear on the difference between internal and external exposure. Epidemiological studies have not been done or are inconclusive.

Thomas, who has lived with his family on Mercer Island for seven years, is passionate that anyone who is concerned about exposure from Hanford is informed about the risks.

One study showed that 90 percent of Downwinders are aware of the releases of radiation but only 20 percent believe they were exposed, he said.

“It is our belief that individuals have to be aware of what resources are available, understand what they can do to help themselves and friends and relatives,” he explained.

“Many individuals tell us when they tell their doctor that they are a Downwinder, their physician says they don’t know what that means,” said Thomas, a trained pharmacist with graduate degree in public health.

Last month, in perhaps one of the last major actions of the HCHP, 26,000 informational brochures were mailed to physicians in the Pacific Northwest and Northern California. Their purpose is to prepare doctors to treat patients exposed to iodine 131. They will mail another 9,000 postcards to individuals on their mailing list in a “tell-a-friend” campaign.

“There are Downwinders on Mercer Island,” Thomas said. “There are many Island names on our mailing lists.”

For more information, check www.hanfordhealth.info or call a toll free 1-888-422-8737 to be added to a mailing list or receive free information.