# Presentation: 630124

## Get the Facts About Exposure to I-131 Radiation	

## Introduction

***Get the Facts About Exposure to I-131 Radiation***** is about the possible effects on human health of radioactive iodine (or I-131) from atomic bomb tests during the Cold War years.**
**Companion items to this presentation: **
**Brochure, *****Get the Facts About Exposure to I-131 Radiation***
***Making Choices: Screening for Thyroid Disease***
***What You Need to Know About Thyroid Cancer***

## U.S. Tested Atomic Bombs during the Cold War, 1951 – 1963

- I-131:
- Radioactive substance released in fallout
- Collects in thyroid gland

**Notes:**
During the Cold War in the 1950s and early 1960s, the U.S. government conducted about one hundred nuclear weapons (atomic bomb) tests in the atmosphere at a test site in Nevada. The radioactive substances released by these tests are known as "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.

Among the numerous radioactive substances released in fallout, there has been a great deal of concern about and study of one radioactive form of iodine—called iodine-131, or I-131. I-131 collects in the thyroid gland.

## U.S. Aboveground Atomic Bomb Tests, 1951-1962

- Conducted at a test site in Nevada
- Released radioactive substances into atmosphere—fallout

**Notes:**
During the Cold War, the United States developed and tested nuclear weapons in an effort to deter and to be fully prepared for nuclear attacks from other nations. Most of the aboveground U.S. nuclear tests were conducted in Nevada from 1951 to 1963.  As a result of these tests, potentially health harming radioactive materials were released into the atmosphere and produced fallout.  

## What Is I-131?

- Radioactive iodine, or iodine-131:
- Radioactive substance
- Released by atomic bomb tests
- Carried thousands of miles by winds

**Notes:**
I-131 was among the radioactive materials released by the atomic bomb tests. It was carried thousands of miles away from the test areas on the winds. 

## What Is I-131?

- Half gone in 8 days
- Almost all gone (less than 1% remained) after 80 days
- Gives off radiation as it breaks down

**Notes:**
The “active” in “radioactive” means that unstable substances produced in nuclear reactions break down and change, so that they eventually become stable and no longer release radiation.  The rate of breakdown can occur quickly in some radioactive substances, often within a few days.  Half of the I-131 released during each atomic bomb test was gone in about 8 days. Almost all of it was gone (less than 1% remained) 80 days after the test. Like all radioactive substances, I-131 releases radiation as it breaks down.  It is this radiation that can injure human tissues.  But I-131’s steady breakdown means that the amount of I-131 present in the environment after a bomb test steadily decreased. Therefore, farm animals that grazed in fields within a few days after a test would have consumed higher levels of I-131 than animals grazing later.

## Informing Americans

- Congress directed government health agencies to:
- Investigate the I-131 problem
- Make recommendations to Americans who might have related health risks
- Two I-131 reports published, in 1997 and 1999

**Notes:**
Congress directed government health agencies to investigate the I-131 problem many years ago, and to make recommendations to Americans who might have related health risks.

Reports were published in 1997 and 1999. This presentation continues the effort to educate the American people about the potential health risks from exposure to I-131 from the Nevada Test Site during the Cold War years.

## Gathering Information About Exposure to I-131

- Record-keeping incomplete
- Not much information is available
- Work continues despite challenges

**Notes:**
Gathering information turned out to be very complicated.  Record-keeping was incomplete at the time of the bomb testing. Much of the information needed to calculate an individual’s dose of I-131 and associated risk is not available.
In addition to nuclear testing in Nevada, Americans were exposed to I-131 through nuclear testing elsewhere in the world (mainly in the 1950s and 1960s), nuclear power plant accidents (such as the Chornobyl accident in 1986, also known as Chernobyl) , and releases from atomic weapons production plants (such as the Hanford facility in Washington state from 1944 to 1957). Scientists are working to find out more about ways to measure and address potential exposure to I-131 from other sources. Scientists are also working to find out more about other radioactive substances released by fallout and about their possible effects on human health.
Despite such challenges, government agencies organized expert scientific teams that have devoted many years to learning more about I-131.

Note to Presenter: For more information about sources of nuclear fallout and the gathering of data, you may visit the Web site of the Agency of Toxic Substances and Disease Registry at www.atsdr.cdc.gov.

## Exposure to I-131—Potential Risks?

- I-131 collects in thyroid gland
- Exposure, especially during childhood, may increase the risk of thyroid disease, including thyroid cancer

**Notes:**
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 Gland

- Front of neck, overlying windpipe
- Regulates:
- Heart rate
- Blood pressure
- Temperature
- Childhood growth and development

**Notes:**
The thyroid controls many body processes, including heart rate, blood pressure, and body temperature, as well as childhood growth and development. It is located in the front of the neck, just above the top of the breastbone and overlying the windpipe. 

## Thyroid Disease

- Noncancerous
- Amount of hormones
- Noncancerous lumps/nodules
- Cancer
- Cancerous lumps/nodules

**Notes:**
There are two main types of thyroid diseases: noncancerous thyroid disease and thyroid cancer.

Some thyroid diseases are caused by changes in the amount of thyroid hormones that enter the body from the thyroid gland. Doctors can screen for these with a simple blood test. Noncancerous thyroid disease also includes lumps, or nodules, in the thyroid gland that are benign and not cancerous.

Thyroid cancer occurs when a lump, or nodule, in the thyroid gland is cancerous. 

## Thyroid Cancer

- Uncommon (accounts for less than 2% of cancers)
- Typically slow-growing
- Highly treatable and usually curable
- Exposure to I-131 may increase risk

**Notes:**
Thyroid cancer is uncommon and is usually curable.

Exposure to I-131 may increase a person’s risk of developing thyroid cancer. It is thought that risk is higher for people who have had multiple exposures and for people exposed at a a younger age. Thyroid cancer accounts for less than 2 percent of all cancers diagnosed in the United States. Typically, it is a slow-growing cancer that is highly treatable and usually curable. About 95 out of 100 people who are diagnosed with thyroid cancer survive the disease for at least five years after diagnosis, and about 92 out of 100 people survive the disease for at least 20 years after diagnosis.

## Causes of Thyroid Cancer

- Cause of most cases not known
- Childhood exposure to radiation increases risk
- Adult thyroids appear more resistant
- Few people exposed to I-131 as adults develop thyroid cancer

**Notes:**
The cause of most cases of thyroid cancer is not known.  Exposure to I‐131 can increase the risk of thyroid cancer. But even among people who have documented exposures to I-131, few develop this cancer. 

It is known that children have a higher-than-average risk of developing thyroid cancer many years later if they were exposed to radiation. This knowledge comes from studies of people exposed to x-ray treatments for childhood cancer or noncancerous head and neck conditions, or as a result of direct radiation from the atomic bombings of Hiroshima and Nagasaki.

The thyroid gland in adults, however, appears to be more resistant to the effects of radiation. There appears to be little risk of developing thyroid cancer from exposure to I-131 or other radiation sources as an adult. 

## How Were Americans Exposed to I-131?

**Notes:**
I-131 was among the radioactive materials released by the atomic bomb tests. It was carried thousands of miles away from the test areas on the winds. Because of wind and rainfall patterns, the distribution of fallout varied widely after each test. Therefore, although all areas of the U.S. received fallout from at least one nuclear weapons test that was conducted in Nevada, certain areas of North America received more fallout than others.
Scientists estimate that the larger amounts of I-131 fell over some parts of Utah, Colorado, Idaho, Nevada, and Montana. But I-131 traveled to all states, particularly those in the Midwestern, Eastern, and Northeastern United States. Some of the I-131 collected on pastures and on grasses, where it was consumed by cows and goats.
When consumed by cows or goats, I-131 collects in the animals’ milk. Eating beef from cows exposed to I-131 carried little risk. Much of the health risk associated with I-131 occurred among milk-drinkers -- usually children. From what is known about thyroid cancer and radiation, scientists think that people who were children during the period of atomic bomb testing are at higher risk for developing thyroid cancer.

## I-131 and Grazing Animals

- I-131 breaks down steadily:
- Animals grazing within few days of test might have consumed high levels
- Greater potential exposure to I-131 from backyard or farm milk:
- Farm milk unprocessed
- Processing/shipping milk allowed more time for I-131 to break down

**Notes:**
I-131’s steady breakdown means that the amount of I-131 present in the environment after a bomb test steadily decreased. 

Fresh milk from backyard or farm cows and goats usually contained more I-131 than store-bought milk. This is because processing and shipping milk allowed more time for the I-131 to break down.

Goat’s milk generally contained more I-131 because goats concentrate significantly more I-131 in their milk than cows do.

People received little exposure from eating fruits and leafy vegetables as compared to drinking fresh milk. This is because I-131 fell on the surface of the fruits and vegetables. So peeling of washing them removed most of the I-131. Little I-131 was transferred to the inside of the plant.

## Affected Areas of U.S. 

- The larger amounts of I-131 fell over :
- Utah
- Colorado
- Idaho
- Nevada
- Montana
- I-131 traveled to all states, particularly those in the Midwestern, Eastern, and Northeastern U.S.

**Notes:**
I-131 was carried thousands of miles away from the test areas on the winds.

Scientists estimate that the larger amounts of I-131 fell over some parts of Utah, Colorado, Idaho, Nevada, and Montana. But I-131 also traveled to all states, particularly those in the Midwestern, Eastern, and Northeastern United States.  

Note to Presenter: For more information on what areas of the United States were most affected by I-131 fallout, please visit www.cancer.gov.

## People Most Affected 

- Children (under age 15) between 1951 and 1963:
- Thyroid glands still developing
- Likely milk drinkers

**Notes:**
People younger than 15 at the time of aboveground testing (between 1951 and 1963) who drank milk, and who lived in the Mountain West, Midwestern, Eastern, and Northeastern United States probably have a higher thyroid cancer risk from exposure to I-131 in fallout 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.

## People Most Affected

- The amount of I-131 people absorbed depends on :

- 1.	Age (between 1951 and 1963)
- 2.	Milk drinking
- 3.	Childhood residence

**Notes:**

The amount of I-131 people absorbed depends on:

1. Their age during the testing period (between 1951 and 1963)
2. The amount and source of milk they drank in those years
3. Where they lived during the testing period

## People Most Affected

- Age:
- People now 40 or older
- Especially those born between 1936 and 1963

**Notes:**
People with the highest risk of developing thyroid cancer from exposure to I-131 were children during the period of atomic bomb testing, and are now 40 years of age or older.

## People Most Affected

- Childhood milk drinkers have increased risk, particularly those who drank fresh milk from farm or backyard cows and goats

**Notes:**
Age and residence during the Cold War years are usually  known. But few people can recall the exact amounts or sources of the milk they drank as children. While the amount of milk consumed is important in determining exposure to I-131, it is also important to know the source of the milk. Fresh milk from backyard or farm cows and goats usually contained more I-131 than store-bought milk. This is because processing and shipping milk allowed more time for the I-131 to break down.

Note to Presenter: To help assess an individual’s risk, please see the National Cancer Institute’s publication Making Choices: Screening for Thyroid Disease, available through the Cancer Information Service at 1-800-4-CANCER or via the Web at www.cancer.gov.

## People Most Affected

- Childhood residence:
- Mountain West
- Midwest
- East
- Northeast

**Notes:**
Scientists estimate that the larger amounts of I-131 fell over some parts of Utah, Colorado, Idaho, Nevada, and Montana. But I-131 also traveled to all states, particularly those in the Midwestern, Eastern, and Northeastern United States.

## How Doctors Screen for Thyroid Cancer

- No single or specific symptom
- Examination by touch
- Most thyroid lumps are not cancer

**Notes:**
There is no single or specific symptom of thyroid cancer. Most commonly, doctors screen for thyroid cancer by feeling the gland, to check for a lump or nodule. If a doctor feels a nodule, it does not mean cancer is present. Most thyroid nodules found during a medical exam are not cancer.
People who think they may be at risk for thyroid cancer should discuss this concern with their doctor. The doctor may suggest a schedule for checkups. 

Note to Presenter: For information on the symptoms of thyroid cancer, please see the National Cancer Institute’s publication What You Need to Know About Thyroid Cancer, available through the Cancer Information Service at 1-800-4-CANCER or via the Web at www.cancer.gov.

## If Thyroid Lump Is Found

- Checked by:
- Ultrasound—to locate and describe lump
- Biopsy—to determine if lump is cancerous

**Notes:**
There are two methods of investigating a thyroid lump or nodule: 1) ultrasound, to locate and describe the lump, and 2) biopsy, to determine if the lump is cancerous. 

Note to Presenter: For more information about testing for thyroid cancer, see the National Cancer Institute’s publication What You Need to Know About Thyroid Cancer, available through the Cancer Information Service at 1-800-4-CANCER or via the Web at www.cancer.gov.

## Ultrasound

- Creates pictures by bouncing sound waves off thyroid
- Painless, quick
- Cannot determine if lump is cancer

**Notes:**
Thyroid ultrasound creates pictures by bouncing sound waves off the gland.  This technique is painless and quick. But it cannot determine whether a lump is cancerous. 

The ultrasound device uses sound waves that people cannot hear. A computer uses the echoes to create a picture called a sonogram. From the picture, the doctor can see how many nodules are present, how big they are, and whether they are solid or filled with fluid.

## Fine Needle Aspiration Biopsy

- Cells withdrawn from nodule
- Cells examined in lab with microscope
- Fast and carries minimal risk
- May confirm whether nodule is cancer

**Notes:**
Confirmation of cancer requires biopsy, usually using fine needle aspiration. Cells removed from a nodule during biopsy are directly examined in the laboratory with a microscope.

Fine needle aspiration biopsy—in which a few cells are withdrawn from a nodule in a thin, hollow needle—is fast and carries minimal risk. Most people with a thyroid nodule who have a biopsy turn out not to have thyroid cancer. But even noncancerous nodules require medical follow-up.
If a diagnosis cannot be made from the biopsy, the doctor may operate to remove the nodule. A pathologist then checks the tissue for cancer cells.

## Treatment for Thyroid Cancer

- Surgery to remove thyroid gland
- Replacement of thyroid hormone in pill form

**Notes:**
If thyroid cancer is found, it is treated by removing the thyroid gland. 

Unlike many other far more common and threatening cancers, thyroid cancer is generally cured by surgery, often along with postoperative radioiodine treatment.

People who undergo surgery will need to take thyroid hormone replacement pills for the rest of their lives. Although this is inconvenient and expensive, cancer survival rates are excellent. In fact, the cause of death among people who once had thyroid cancer is rarely the result of the return or spread of the same cancer.

Living with a serious disease like thyroid cancer isn’t easy. A cancer diagnosis can be devastating. Some people find they need help coping with the emotional and practical aspects of their disease. Doctors and other health professionals can help with concerns about treatment and managing side effects. 

Support groups can help also. The National Cancer Institute’s Cancer Information Service can help put you in touch with support groups in your community. Call 1-800-4-CANCER for more information.

## Key Facts

- I-131 breaks down rapidly in the atmosphere and environment
- Exposure was highest in the first few days after each nuclear test explosion
- Most exposure occurred through drinking fresh milk

**Notes:**
Scientists know that:
I-131 breaks down rapidly in the atmosphere and environment
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. This is because although I-131 was deposited on fruits and leafy vegetables, the I‐131 in fallout was deposited only on the surface. People generally wash or peel fruits and leafy vegetables.

## Key Facts

- Thyroid cancer is uncommon, usually curable, and approximately 2 to 3 times more common in women
- Scientists think that:
- Risk for thyroid cancer increases with exposure, but even among people exposed to I-131, few develop this cancer
- People exposed as children have a higher risk than people exposed as adults

**Notes:**
Thyroid cancer is uncommon, usually curable, and approximately 2 to 3 times more common in women.

Reliable information about I-131’s impact on human health has been difficult to collect, but scientists think that:
 Risk for thyroid cancer increases with exposure, but even among people exposed to I-131, few develop this cancer
 People exposed as children have a higher risk than people exposed as adults

## Get More Information

- Talk to your doctor or health care provider
- Read *Get the Facts**** ****About Exposure to I-131 Radiation*
- Read *What You Need to Know About Thyroid Cancer*
- Calculate potential risk with the National Cancer Institute's* Making Choices: Screening for Thyroid Disease*
- Call 1-800-4-CANCER
- Visit *www.cancer.gov, *search* *keyword: I-131