CDC: No incr thyr risk w/rad dose at Hanford

[Chuck Cooper <ccc@pp.pdx.edu>]

June 21, 2002

Contact: CDC Media Relations

(404) 639-3286



http://www.cdc.gov/od/oc/media/pressrel/r020621.htm



Press Release



CDC Releases Hanford Thyroid Disease Study Final Report



Data Show Risks of Thyroid Disease About the Same Regardless of

Radiation Dose from Hanford



Findings announced from the Hanford Thyroid Disease Study (HTDS) Final

Report show that the risks of thyroid disease in study participants

were about the same regardless of the radiation dose they received

from radioactive iodine-131 from the Hanford Nuclear Weapons

Production Facility in Washington State between 1944 and 1957. While

thyroid disease was found, researchers determined that rates of the

disease in the study participants were about the same as rates in

other populations.



The Centers for Disease Control and Prevention (CDC) and the Fred

Hutchinson Cancer Research Center released the findings of the 13-year

study at a community meeting in Richland, Washington.



"We used the best scientific methods available, and we did not find an

increased risk of thyroid disease in study participants from exposure

to Hanford's iodine-131," said Paul Garbe, D.V.M, epidemiologist and

CDC's scientific advisor for the study. "If there is an increased risk

of thyroid disease, it is too small to observe."



The HTDS research team studied all types of thyroid diseases and

examined how the rates varied in relation to participants' estimated

radiation doses from Hanford's iodine-131.



"On the basis of a study population of 3,440 people, we found that

people with higher doses of radiation had about the same amount of

thyroid disease as people with lower doses," said Scott Davis, PhD,

Fred Hutchinson's principal investigator for the HTDS. "We analyzed

the data a number of ways, and the results were the same."



The research team also found that the rates of thyroid disease in the

people who participated in the HTDS were generally consistent with the

rates of disease in other populations in the United States, based on a

review of published scientific literature conducted after the release

of the HTDS Draft Report in 1999.



"Thyroid disease is fairly common in other populations across the

country, especially among older people and women," Garbe said.

"However, we understand the concern that people in the Hanford region

have about thyroid disease, given their exposure to iodine-131, and we

want to provide as much detail as possible about our findings and what

they mean."



The HTDS focused on a group of people who were young children when

they were exposed to iodine-131 from Hanford between 1944 and 1957.

Iodine-131 accounted for most of the radiation dose to the people

exposed to Hanford's radiation. Scientists believe that young children

receive a higher dose to the thyroid gland than adolescents and adults

for the same level of exposure and that the thyroid gland in young

children may be more sensitive to the effects of radiation.



The HTDS study population represents a sampling of people born between

1940 and 1946 to mothers who lived in seven counties in Washington

State: Benton, Franklin, Adams, Walla Walla, Okanogan, Ferry, and

Stevens. Each participant underwent a complete evaluation for thyroid

disease as part of the study. Detailed information about what

participants ate and where they lived were also collected as a part of

the study.



Study participants had a wide range of possible doses to the thyroid

gland, from very high to very low doses. This range enabled

researchers to compare groups of people who have similar

characteristics (such as birth, diet and lifestyle) but different

levels of exposure. This approach of studying a single population

comprising individuals with different levels of exposure has been used

extensively in assessing the effects of radiation exposure in human

populations.



A committee of the National Academy of Sciences evaluated the HTDS at

three stages in the study. Other independent scientists and members of

the public provided input to the HTDS research throughout the study.



Congress mandated the HTDS in 1988 after the U.S. Department of Energy

made public documents revealing that large quantities of radioactive

materials were released from the Hanford Nuclear Weapons Plant in the

1940s and 1950s, especially in 1945.



CDC protects people's health and safety by preventing and controlling

diseases and injuries; enhances health decisions by providing credible

information on critical health issues; and promotes healthy living

through strong partnerships with local, national, and international

organizations.



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