Fallout Studies Incomplete, Scientist Says Releases From Weapons Tests Must Be Added To Hanford Doses For Accuracy, He Argues

The public’s exposure to airborne radiation from Hanford and the Nevada Test Site during the Cold War should be added up for a full accounting of public health risks, an expert says.

“This is a public’s-right-to-know issue,” said Owen Hoffman, a scientist who recently conducted a radiation dose-reconstruction study around the government’s Oak Ridge, Tenn., weapons site.

The issue is timely in the Northwest, where health officials in Washington, Oregon and Idaho have promised the public individual calculations of their doses from Hanford by this fall.

On Friday, Hoffman showed a U.S. Centers for Disease Control & Prevention panel meeting in Spokane how he used a computer model to add up Oak Ridge releases and bomb-test fallout of radioactive Iodine 131 for the state study in Tennessee.

The CDC’s Hanford Health Effects Subcommittee oversees studies of downwinders, including a contentious effort to establish a medical monitoring program to screen exposed people for health problems.

Iodine 131 in bomb fallout was a significant contributor to the Oak Ridge doses, Hoffman said.

“Exposure to Iodine 131 from weapons fallout is the big public health impact of the Cold War era. That should be kept in mind when doing localized studies, like Oak Ridge and Hanford,” he said.

Iodine 131 was the main pollutant released from Hanford during the manufacture of plutonium for nuclear bombs between 1945 and 1960. It was blown downwind, where it settled on grass.

Cows and goats ate the grass, and the contamination was passed on to people when they drank milk. It is riskiest for babies and small children, who have tiny thyroid glands that can be damaged by radiation. People exposed as infants who drank milk from back yard goats or cows are most at risk.

About 150 million curies of Iodine 131 were released from Nevada bomb tests, mostly between 1951 and 1957. Hanford’s releases totaled approximately 900,000 curies, studies show.

During Friday’s meeting, Hoffman showed how fallout doses in Spokane and Ferry counties sometimes exceeded the Hanford doses, increasing long-term health risks and confounding efforts to find a Hanford-specific dose response in exposed people.

His fallout data came from a massive National Cancer Institute study on weapons fallout released in 1997.

There was more bomb fallout in Spokane than in the Columbia Basin counties near Hanford because there was more rainfall in this area to carry the Iodine 131 to the ground, he said.

A man born in Spokane County in 1944 who drank milk from a backyard cow would have received 1.9 to 73 rads from Hanford; 1.1 to 31 rads from the Nevada Test Site. The cumulative dose, 3.3 to 92 rads, involves more than simple addition, Hoffman said.< Today’s annual radiation safety limit for the public is 0.17 rads.

A typical woman born in Lewiston in 1950 would have absorbed between 3.2 and 100 rads from Hanford and bomb fallout combined, with fallout contributing up to 99 percent of that dose.

A 100-rad dose as an infant would give her a 1 in 100 chance of developing thyroid disease. “At Oak Ridge, we’ve centered on risk and have developed a high degree of rapport with the affected community,” said Hoffman, a radiation expert and president of the private Center for Risk Analysis in Oak Ridge.

Thousands of Hanford downwinders have asked the state for their individual dose estimates. But the Individual Dose Assessment Project (IDA) has been delayed due to scientific controversies over the accuracy of the radiation dose estimates used in the Hanford Thyroid Disease Study, released in draft form in January and now undergoing scientific peer review.

Meanwhile, all three Northwest health agencies have asked CDC to add up the Hanford and fallout doses.

The effort to combine dose and risk estimates from multiple sites is a national issue that CDC should take on because of the cost, said Ellen Haars, IDA program manager for the Washington Department of Health and a member of CDC’s Hanford panel.

But CDC staff has been reluctant, citing scientific disagreements with Hoffman’s approach.

“Combining doses and risks from multiple sites could be difficult, and maybe even impossible,” said Charles Miller, chief of CDC’s radiation studies branch, in a June 15 letter to HHES member Trisha Pritikin of Berkeley, a lawyer and Hanford downwinder.

“Owen Hoffman clearly showed us today that this isn’t impossible,” Pritikin said Friday.

Several panel members expressed interest in Hoffman’s approach. But they agreed to defer a resolution calling on CDC for the cumulative doses until they hear from agency staff later this year.