Baby Tooth Science
The atom bomb tests over the Nevada desert are etched in the American consciousness, even though they ended nearly half a century ago. The clouds that looked like gigantic mushrooms rising into the stratosphere remind us of the Cold War-era American-Soviet race to test and manufacture as many nuclear weapons as possible to fight what many felt would be an inevitable nuclear war.
Those days are gone. The Cold War is over. Stockpiles of nuclear weapons are shrinking. All-out nuclear war, while still possible, is no longer regarded as inevitable. And testing has ended ? in the atmosphere and below the ground. Thus, it is tempting to think of bomb tests as a relic of history, with no current relevance.
But the tests ARE relevant. The Comprehensive Test Ban Treaty of 1996, ratified by 153 countries, has still not been endorsed by the U.S. Senate, or other atomic nations. Thus, testing could legally resume at any time. Moreover, research on health hazards of test fallout is far from complete.
Some want to close the book on bomb test studies, citing the age of the tests and the difficulty of understanding health risk. But measuring risk is possible, thanks to – of all things – baby teeth.
Atomic Tests in 1950s Create Need for First Tooth Studies
Studying radiation in baby teeth was an unknown technique when U.S. atmospheric nuclear weapons tests started. By the mid-1950s dozens of weapons had been detonated, including hydrogen bombs one thousand times more potent than atomic bombs. The 422 American and Soviet nuclear explosions into the atmosphere during the arms race equaled the yield of 40,000 Hiroshima bombs.
Fallout from bomb tests consisted of over 100 radioactive and cancer-causing chemicals, not found in nature. Each chemical affects the body differently. Iodine-131 attacks the thyroid gland, Cesium-137 disperses into all soft tissues, and Strontium-90 attaches to bone and teeth. The mushroom clouds in Nevada moved eastward with prevailing winds across the continent, where fallout re-entered the environment through precipitation. Scientific measurements showed that only 2 or 3 days after a Nevada explosion, fallout from the test could be present in rain or snow throughout the country, even the east coast 2500 miles away.
Soon after the Nevada tests began, the U.S. Atomic Energy Commission began the first program measuring radioactivity levels in human bodies by testing Strontium-90 in bones from autopsies in the U.S. and in Europe. The AEC program showed that Sr-90 levels varied by geographic area, and were greater in infants and children. (1) The program also became infamous for its failure to request family permission before testing skeletons. (2)
Although Sr-90 was just one of the 100-plus chemicals in fallout, it quickly became the favorite for in-body testing, as its half life of 28.7 years makes it detectable for a long period after a bone or tooth is extracted from the body. But Sr-90 was also recognized as one of the most harmful components of the clouds. It was known to penetrate into the bone marrow, where red and white blood cells crucial to the immune response are formed. (3)
Sr-90 became a standard part of the American vocabulary during the Cold War. In the 1956 presidential campaign, Democratic nominee Adlai Stevenson declared Sr-90 as:
"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." (4)
One month after this statement, an article in Newsweek described the Sr-90 threat:
"the testing of hydrogen bombs may have already propelled enough strontium 90, the most pernicious aftermath of nuclear fission, into the stratosphere to doom countless of the world’s children to inescapable and incurable cancer." (5)
With the AEC bone program largely a secret government venture, the need for a more public study of fallout in bodies became clear. In August 1958, biochemist Herman Kalckar proposed an international, long-term program measuring fallout in baby teeth. Kalckar noted that young children "take up radioactive strontium and caesium more intensely than adolescents and adults." (6)
Citizens and Scientists Collaborate, Tooth Study Helps End Testing
Kalckar’s idea was an instant hit. The Greater St. Louis Citizens Committee for Nuclear Information, a combination of Washington University scientists and concerned local citizens, began a study in December 1958. Teeth donations were solicited by distributing forms to schools, libraries, churches, dentists, and dental clinics. (7) By the time the study ended over a decade later, over 300,000 teeth had been collected. Federal funds gave some support, but many volunteers handed out forms, collected information from parents, and distributed buttons to children stating "I Gave My Tooth to Science."
Lab testing of baby teeth confirmed the fears of many, namely, the enormous buildup of fallout in baby teeth. The average Sr-90 level in baby teeth for a St. Louis child born in 1963 was about 50 times higher than that of their counterparts born in 1950. (8) The St. Louis tooth study entered the policy arena when Washington University’s Dr. Eric Reiss presented results to the U.S. Senate. Soon after, President John F. Kennedy signed the Partial Test Ban Treaty.
The Washington University tooth study was duplicated in Czechoslovakia, Denmark, Finland, Norway, the United Kingdom, and West Germany. All studies detected the same sharp increase in Sr-90 as bomb testing went on.
The St. Louis study also produced good news: five years after the Treaty went into effect, average Sr-90 in the jawbones of stillborn fetuses plunged about 50%. (8) Post-Treaty reductions were so dramatic that the U.S. government discontinued funding for the St. Louis tooth study in 1970, and studies of Sr-90 in bones of children (1971) and adults (1982), leaving the nation with no program measuring radioactivity in human bodies.
Baby Teeth Used to Address Cancer Risk from Bomb Tests
Talk of fallout causing cancer was common in the bomb test era. A Newsweek article covering the St. Louis tooth study asked "But what about the children who have done their growing while strontium-90 levels were high ? are they liable to develop cancer?" (9) The St. Louis study addressed the buildup of fallout in human bodies, but not cancer risk. Government officials were in no hurry to look at the fallout-cancer link, so the topic went unexamined.
After decades of asserting fallout levels were too low to cause cancer, the government position changed after the Cold War ended. Federal studies estimated that fallout caused 49,000 Americans to develop thyroid cancer, with few fatalities (10), and about 15,000 Americans died of cancer from fallout. (11) Some believed these figures to be gross underestimates; a blue-ribbon European panel estimated worldwide cancer cases from fallout to be 123,200,000, half of them fatal. (12) But U.S. health officials, not eager to consider mass carnage, stopped studies of fallout in 2002.
The St. Louis tooth study, which had been largely forgotten for decades, experienced a rebirth in 2001. Washington University officials were startled to find hundreds of boxes of teeth not used in the study, stored in a remote ammunition bunker. Each tooth is contained in a small enveloped attached to a 3 x 5 card identifying the tooth and its donor. The school transferred the collection of about 85,000 teeth to the Radiation and Public Health Project (RPHP) research group, which was conducting its own study of Sr-90 in baby teeth near nuclear reactors.
RPHP officials recognized that these teeth could be used for a study of cancer risk of "Baby Boomers" now in their 40s and 50s. A sample of the 85,000 teeth was used to locate cancer survivors (through current addresses) and those who died of cancer (through official death records). In December 2010, the International Journal of Health Services published findings of the study, i.e. that "Boomers" born 1959-1961 who died of cancer had Sr-90 levels in their teeth more than twice (+122%) greater than those the same age who are alive and healthy. (13) While more research is needed to estimate casualties, it appears likely that the government figure of 15,000 U.S. cancer deaths from fallout is quite low.
Baby Teeth Play a Role in Public Policy
A long-ago baby tooth study of fallout can be greatly important in shaping current public policy, in several areas. First, it can help explain why 40% of Americans will develop cancer at some point in their life ? many with no known risk factor. Second, it suggests that Americans are being harmed from the same substances produced in 104 nuclear power reactors around the country; the RPHP study of 5,000 baby teeth showed links between Sr-90 in baby teeth and child cancer risk near nuclear plants in New York and New Jersey. (14) Finally, the Comprehensive Test Ban Treaty is still not ratified by the U.S. Senate, and findings of higher cancer rates in "Baby Boomers" from bomb testing underlines the need to ban all further tests of nuclear weapons and their usage in warfare.
Joseph Mangano is Executive Director of the Radiation and Public Health Project.
1. Kulp JL, Eckelmann WR, Schulert AR. Strontium-90 in man. Science 1957;125(3241): 219-27.
2. Leary WE. In 1950s, U.S. Collected Human Tissue to Monitor Atomic Tests. New York Times, June 21, 1995.
3. Pecher C and Pecher J. Radio-calcium and radio-strontium metabolism in pregnant mice. In Proceedings of the Society for Experimental Biology and Medicine. New York: January-April 1941, Volume 46, p. 94.
4. Salisbury HE. Stevenson Calls for World Pact to Curb H-Bomb. New York Times, October 16, 1956.
5. Danger ? Strontium 90. Newsweek, November 12, 1956, p. 88.
6. Kalckar HM. An international milk teeth radiation census. Nature 1958;4831:283-4.
7. Wyant WK. Strontium-90 in St. Louis: 50,000 Baby Teeth. The Nation, June 13, 1959, 535-7.
8. Rosenthal HL. Accumulation of environmental 90-Sr in teeth of children. Hanford Radiobiology Symposium, Richland WA, May 5-8, 1969, 163-71.
9. Moment of Tooth. Newsweek, April 25, 1960, p. 70.
10. National Research Council, Committee on Thyroid Screening. Exposure of the American People to Iodine-131 from the Nevada Bomb Tests. National Academy Press: Washington DC, 1999.
11. Eisler P. Fallout likely caused 15,000 deaths. USA Today, February 28, 2002, p. 1.
12. European Committee on Radiation Research. 2003 Recommendations of the ECRR: The Health Effects of Ionising Radiation Exposure for Radiation Protection Purposes. Green Audit: Aberystwyth, Wales, 2003.
13. Mangano JJ and Sherman JD. Elevated in vivo strontium-90 from nuclear weapons test fallout among cancer decedents: a case-control study using deciduous teeth. International Journal of Health Services 2011;41(1):137-58.
14. Mangano JJ. A short latency between radiation exposure from nuclear plants and cancer in young children. International Journal of Health Services 2006;36(1):113-35.