If you are a schoolkid of the right age, you can’t wait to lose a baby tooth. In many cultures, there is a ritual surrounding it, like the tooth fairy, a mouse who trades your tooth for a gift, or burying the tooth somewhere significant. But in 1958, a husband and wife team of physicians wanted children’s teeth for a far different purpose: quantifying the effects of nuclear weapons testing on the human body.

Louise and Eric Reiss, along with some other scientists, worked with Saint Louis University and the Washington School of Dental Medicine to collect and study children’s discarded teeth. They were looking for strontium-90, a nasty byproduct of above-ground nuclear testing. Strontium is similar enough to calcium that consuming it in water and dairy products will leave the material in your bones, including your teeth.

The study took place in the St. Louis area, and the results helped convince John F. Kennedy to sign the Partial Nuclear Test Ban Treaty.

They hoped to gather 50,000 teeth in a year. By 1970, 12 years later, they had picked up over 320,000 donated teeth. While a few kids might have been driven by scientific altruism, it didn’t hurt that the program used colorful posters and promised each child a button to mark their participation.

Children’s teeth were particularly advantageous to use because they are growing and are known to readily absorb radioactive material, which can cause bone tumors.

Scale

You might wonder just how much nuclear material is floating around due to bombs. Obviously, there were two bombs set off during the war, as well as the test bombs required to get to that point. Between 1945 and 1980, there were five countries conducting atmospheric tests at thirteen sites. The US, accounting for about 65% of the tests, the USSR, the UK, France, and China detonated 504 nuclear devices equivalent to about 440 megatons of TNT.

Well over 500 bombs with incredible force have put a lot of radioactive material into the atmosphere. That doesn’t count, too, the underground tests that were not always completely contained. For example, there were two detonations in Mississippi where the radiation was contained until they drilled holes for instruments, leaving contaminated soil on the surface. Today, sites like this have “monuments” explaining that you shouldn’t dig in the area.

Of course, above-ground tests are worse, with fallout affecting “downwinders” or people who live downwind of the test site. There have been more than one case of people, unaware of the test, thinking the fallout particles were “hot snow” and playing in it. Test explosions have sent radioactive material into the stratosphere. This isn’t just a problem for people living near the test sites.

Results

By 1961, the team published results showing that strontium-90 levels in the teeth increased depending on when the child was born. Children born in 1963 had levels of strontium-90 fifty times higher than those born in 1950, when there was very little nuclear testing.

The results were part of the reason that President Kennedy agreed to an international partial test ban, as you can see in the Lincoln Presidential Foundation video below. You may find it amazing that people would plan trips to watch tests, and they were even televised.

In 2001, Washington University found 85,000 of the teeth stored away. This allowed the Radiation and Public Health Project to track 3,000 children who were, by now, adults, of course.

Sadly, 12 children who had died from cancer before age 50 had baby teeth with twice the levels of the teeth of people who were still alive at age 50. To be fair, the Nuclear Regulatory Commission has questioned these findings, saying the study is flawed and fails to account for other risk factors.

And teeth don’t just store strontium. In the 1970s, other researchers used baby teeth to track lead ingestion levels. Baby teeth have also played a role in the Flint Water scandal. In South Africa, the Tooth Fairy Project monitored heavy metal pollution in children’s teeth, too.

Teeth aren’t the only indicator of nuclear contamination. Steel is also at risk.

Featured image: “Castle Bravo Blast” by United States Department of Energy.