January is Thyroid Awareness Month. Some people may wonder when they see thyroid awareness, about radioactive iodine fall out. During the Cold War in the 1950's and early 1960s, the U.S. government conducted about one hundred atom bomb tests at a site in Nevada. The radioactive substances released by these tests are called "fallout". They were carried thousands of miles away from the test site by winds. As a result, people living in the United States at the time of the testing were exposed to varying levels of radiation. Radioactive iodine or I -131 is one of those radioactive substances.
I-131 collects in the thyroid gland. People exposed to I-131, especially during childhood, may have an increased risk of thyroid disease, including thyroid cancer. Thyroid cancer is usually a slow growing cancer that is highly treatable. About 95 of 100 people who are diagnosed with thyroid cancer survive at least five years after diagnosis.
It is important for people who grew up during the atomic bomb testing between 1951 and 1963 to be aware of risks. People younger than 15 at the time of the above ground testing (between 1951-1963) who drank milk, and lived in the Mountain West, Midwestern, Eastern and Northeastern United States, probably have a higher thyroid cancer risk from exposure to 1-131 than other people. Their thyroid glands were still developing during the testing period. And they were more likely to have consumed milk contaminated with I-131. Fresh milk from backyard or farm cows and goats usually contained more I-131 than store bought milk. That is because processing and shipping milk allowed more time for the I-131 to break down.
The cause of most cases of thyroid cancer is not known. Exposure to I-131 can increase the risk of thyroid cancer. There is no specific symptom of thyroid cancer. Doctors screen for thyroid cancer by feeling the thyroid gland to check for a lump or nodule. Most thyroid nodules are not cancer, however.
If thyroid cancer is found, it is treated by thyroid removal. Those who have their thyroid removed will need to take thyroid hormone replacement pills for the rest of their lives. This is inconvenient and costly, but cancer survival rates are excellent.
Key facts to remember about I-131 and thyroid cancer:
- Exposure was highest in the first few days after each nuclear test explosion.
- Most exposure occurred through drinking fresh milk.
- People received little exposure from eating fruits and leafy vegetables as compared to drinking fresh milk because although I-131 was deposited on fruits and leafy vegetables, the fallout was deposited only on the surface; people generally wash or peel fruits and leafy vegetables.
- Thyroid cancer is uncommon, usually curable, and approximately 2-3 times more common in women.
For more information about any cancer concern, contact:
Cancer Information Service
Holden Comprehensive Cancer Center
UI Hospitals and Clinics
200 Hawkins Drive, 4802 JPP
Iowa City, Iowa 52242