The huge mushroom clouds from atom bomb tests of the 1950s and 1960s are an unforgettable part of the American saga. The tests were cloaked in rhetoric typical of the Cold War, i.e. they were needed to achieve "superiority" over the Soviets in the event of a nuclear war.

But all the patriotic nuclear talk couldn't prevent widespread concern that nuclear war would kill tens of millions. But many were also troubled by fallout in the mushroom clouds, which contained huge amounts of over 100 deadly radioactive chemicals that traveled through the air across the continental U.S. Precipitation brought this fallout back to earth -- and into the food chain and human bodies.

Concerns became so great that scientists and citizens began calling for studies of how much fallout was entering people's bodies, and how much harm it was causing -- especially to the highly-sensitive fetuses, infants, and children. Dr. Herman Kalckar of the National Institutes of Health published an article in August 1958, calling for a baby tooth "census" -- a program of collecting teeth and testing them in laboratories for fallout levels. In particular, Kalckar suggested that Strontium-90 be measured.

Of the more than 100 radioactive chemicals in fallout, Sr-90 was the most feared. Chemically similar to calcium, it attaches to bone and teeth, where it attacks cells, causing cancer. It can penetrate into the bone marrow, where the red and white blood cells so important to the immune response are formed. In 1956, Presidential candidate Adlai Stevenson made a speech singling out the potency of Sr-90:

"This radioactive fallout, as it is called, carries something that's called strontium-90, which is the most dreadful poison in the world. For only one tablespoon equally shared by all the members of the human race could produce a dangerous level of radioactivity in the bones of every individual."

In December 1958, a group of visionary scientists at Washington University in St. Louis, working with the citizen group Committee for Nuclear Information, began collecting baby teeth, locally and across the country. They obtained federal grants to cover their costs, and generated large numbers of volunteers to help with tooth collection. Schools, PTAs, churches, scout groups, dental societies, libraries and clinics all took part. Children were rewarded for donating teeth with a small button bearing a likeness of a boy with a gap in his front teeth, with the phrase "I Gave My Tooth to Science."

A staggering total of about 320,000 teeth were collected over the next dozen years. Lab tests found that children born in 1963 had about 50 times more Sr-90 in teeth than those born in 1950. Washington University officials used their results in testimony to the U.S. Senate leading to the Partial Test Ban Treaty signed by President John F. Kennedy, ending all above-ground atom bomb tests.

Testing had ended, but the thorny question of health hazards to Americans -- especially children -- remained. U.S. childhood cancer rates had climbed in the 1950s and early 1960s, but scientists were stumped as to why. Studies of the fallout-cancer link were only conducted after the Cold War had ended. A 2002 U.S. Centers for Disease Control report calculated that fallout caused 15,000 U.S. cancer deaths, a figure some believed was a gross underestimate. The following year, a blue ribbon European panel reported 61,600,000 cancer deaths worldwide from fallout.

The St. Louis tooth study was seemingly headed for the history books, until 2001, when Washington University officials stumbled upon 85,000 teeth not used in the study in a remote storage area. The school donated the teeth to the Radiation and Public Health Project (RPHP), a research group conducting its own study of Sr-90 in baby teeth, near U.S. nuclear reactors. Each tooth is enclosed in a small envelope attached to a card identifying the tooth donor.

RPHP scientists recognized that these teeth could help answer the long-awaited question of fallout's harm to the health of Americans. The tooth donors, now in their 40s and 50s, could be tracked at current addresses or through death records. And Sr-90 could still be measured in each tooth, as the chemical decays very slowly.

Earlier this month, the first results of the RPHP health study were released in an article in the International Journal of Health Services. Baby teeth of St. Louis baby boomers who died of cancer by age 50 had more than double -- 122 percent more -- the Sr-90 concentration than did Boomers who are alive and healthy. This research, known as a case-control study, is the first evidence that bomb tests harmed Americans using actual levels of fallout in human bodies. It is not yet possible to estimate the number of cancer victims from fallout, but it appears that the CDC estimate of 15,000 deaths is too low.

Bomb testing into the atmosphere ended in 1963, and even below-ground tests stopped in 1992. The study of fallout's impact on cancer, however, is not an idle look into history, but has much current relevance, namely:

1. With 150 million Americans alive who were exposed to above-ground bomb tests, and with 40% expected to be diagnosed with cancer at some point, it is important to understand causes of the disease.

2. The Comprehensive Test Ban Treaty of 1996, which proposes to end all atom bomb tests, has been ratified by 153 nations - but not the U.S. President Obama has pledged to convince the U.S. Senate to ratify the treaty, and information on health risk is an important aspect supporting the Treaty.

3. The 104 nuclear power reactors in the U.S. produce the same mixture of chemicals as atom bomb tests. Most of this toxic mixture is stored as high level nuclear waste, but some is emitted into the air and water, and enters human bodies. The RPHP study of baby teeth showed that Sr-90 levels in children near reactors were 30-50 percent greater than children in distant areas, and that levels were rising sharply over time, as aging reactors corrode.

Studying health risks of radioactive emissions from both weapons and reactors has been a highly politicized issue, as the military and industries producing these chemicals are not eager to present findings of harm. However, the only way to truly reduce cancer rates is to understand causes and take preventive actions. Baby teeth, even those from half a century ago, hold the clues to one such cause.

CONTACT:

Samuel S. Epstein, M.D.

Professor emeritus Environmental & Occupational Medicine

University of Illinois at Chicago School of Public Health

Chairman, Cancer Prevention Coalition

Chicago, Illinois

www.preventcancer.com

Joseph Mangano, MPH, MBA

Executive Director, Radiation and Public Health Project

New York

www.radiation.org