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The Smithsonian and State Historical Society of Missouri both document the membership card + button together as the reward given to children participating in the St. Louis Baby Tooth Survey. The program began in the late 1950s and ran through the 1960s, collecting more than 300,000 teeth to study strontium-90 from nuclear fallout. Louise Reiss published major early findings in Science on November 24, 1961.
That paper analyzed 20,439 teeth collected from St. Louis-area children during 1959 and 1960 and demonstrated that baby teeth could be used to track Sr-90 deposition.
As atmospheric nuclear testing increased, researchers saw Sr-90 levels in children\'s teeth rise.
Later analyses found the pattern particularly dramatically: levels climbed sharply through the nuclear-testing era and then declined after atmospheric testing stopped. Washington University\'s historical account says the research demonstrated that Sr-90 in baby teeth rose and fell in correlation with atomic bomb testing.
One published historical dataset shows the average Sr-90 concentration in incisors rising from about 0.165 in children born in 1950 to 10.453 for those born in 1964—more than sixty times the 1950 level—before subsequently declining.This is where your little pin connects to major American history.
The Baby Tooth Survey results became part of the growing scientific and political argument against atmospheric nuclear testing. Members of the project\'s scientific group testified during congressional consideration of a nuclear test-ban treaty.
President John F. Kennedy was aware of the research while the United States, Soviet Union and United Kingdom were negotiating what became the 1963 Partial Nuclear Test Ban Treaty, which prohibited nuclear weapons tests in the atmosphere, outer space and underwater. Harvard\'s current history of the project describes the Baby Tooth Survey as playing an important role in Kennedy\'s decision to sign the treaty.
In 2001, approximately 100,000 untested teeth were discovered in an abandoned armory owned by Washington University.
Researchers eventually realized they had an extraordinary scientific time capsule.
Harvard researchers estimate those surviving teeth represent approximately 55,000 original donors. Harvard is now conducting the St. Louis Baby Tooth–Later Life Health Study, reconnecting with participants and using the old teeth to investigate how early-life environmental exposures may relate to health decades later. More than 6,500 original donors had joined that later-life study according to Harvard\'s project page. Harvard\'s St. Louis Baby Tooth–Later Life Health Study is ongoing. Of the roughly 100,000 unused teeth rediscovered in 2001, researchers estimate they represent about 55,000 original children, and more than 6,500 original donors have enrolled in the modern study. Harvard is still inviting people who donated teeth decades ago to find out whether their tooth is among those preserved.
What they\'re doing with the teeth now
Researchers can actually examine layers of tooth dentin corresponding to prenatal and early-infant life. Using modern laser-based analysis, they\'re measuring substances such as lead deposited while the teeth were developing and connecting those measurements with the donors\' health roughly six decades later. In one recent analysis, participants were 55–75 years old, averaging about 62.
And they\'ve moved into Phase II. Participants can now provide additional samples including blood, toenail clippings and drinking water, allowing researchers to combine today\'s exposures and health information with the biological record preserved in their childhood teeth.
They are getting new results — including in 2026
A study announced by Harvard in February 2026 found an association between prenatal lead exposure measured in the old baby teeth and poorer cognitive function later in adulthood among women. That\'s an association, not proof that the lead caused an individual\'s later cognitive outcome.
Another paper published in August 2026 examined 704 participants and reported an association between early-life lead exposure and later-adult BMI among women, with the strongest evidence pointing to exposure during roughly the first six months after birth. The researchers did not find a significant association among men. Again, that\'s an epidemiological association rather than proof of individual causation.
The project has also produced recent research on mental health, cognition and environmental exposures. Its publications include a 2025 JAMA Psychiatry paper on early lead exposure and later mental health and a 2025 Scientific Reports paper examining childhood cognitively stimulating activities and cognition later in life.
And there\'s a very St. Louis-specific development
In July 2025, researchers used this cohort to study people who had lived near Coldwater Creek, the north St. Louis County area contaminated by radioactive waste associated with Manhattan Project-era uranium processing. They reported that childhood residence near the creek was associated with higher cancer incidence later in life.
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