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Nuclink: Journal of Current Radiation and Public Health Issues Volume 1, Number 6 FURTHER OBSERVATIONS ON STRONTIUM-90 IN BABY TEETH AND
EARLY CHILDHOOD CANCER INTRODUCTION
From 1958 to 1964, an exponential rise in strontium-90 levels was detected in the baby teeth of thousands of American children, collected mainly from St. Louis, from about one picocurie per gram calcium from children born in 1958 to 11 picocuries for children born in 1964. For children born in 1949 the level was barely detectable at 0.1 pCi/gr ca. With the termination by President Kennedy of above-ground nuclear weapons tests in 1963, the levels declined rapidly to 4 .6 picocuries by 1970, the same year the St. Louis baby teeth study was terminated by the Nixon Administration, presumably convinced that the rates of decline observed from 1964 to 1970 would continue indefinitely. As indicated above, the projected levels were expected to be too low to be detected by the 1980s. (2) (3) (4) As of August 2000, RPHP has analyzed Sr90 levels in 1493 baby teeth from persons born from 1946 to 1996, with 1440 from those born after 1964. From 1965 to 1970, the RPHP average and annual peak levels confirm the sharp drop observed in the St. Louis teeth. There is a lesser decline in the average values during the 1970s, when commercial nuclear power reactors began to operate in increasing numbers. However, the average RPHP levels after 1980, at about 1.5 picocuries per gram calcium, were at the same surprisingly high levels observed in the years 1954 to 1958, which impelled the Eisenhower Administration to begin measurements of radioactivity in milk, water and produce in 1954. The peak values observed by RPHP after 1970 are so high as to suggest that fallout from reactor emissions had replaced bomb test fallout as a threat to the health of Americans. GEOGRAPHIC DISTRIBUTION OF 1349 BABY TEETH FOR THOSE UNDER 20
Table 1 below indicates that most of the tooth donors to the RPHP Tooth Fairy study born after 1979 live in the states of California, Florida, New Jersey and New York, and live sufficiently close to an operating reactor to respond to our appeals to contribute teeth. In all these areas it is clear that the average level of Sr90 per gram calcium ranges roughly between one and two picocuries,is the level reached by the first St. Louis baby teeth study during the years 1954 to 1958. Thus we have now established that since 1980, when Federal monitoring of Sr90 uptake has been discontinued, there should be the same degree of national concern about the impact of high Sr90 levels on the health and viability of our newborn. Table 1 shows that there are statistically significant variations in the geographic levels in specific Zip code areas where the collection and analysis of teeth has been concentrated, with the highest levels in Florida. When one considers that approximately 80 million children have been born in the past 20 years, it is clear that we would need to analyze many more thousands of teeth to have a full account of the many factors explaining why we have higher than average levels near operating reactors, taking into account: proximity, ground water flows, wind patterns, dietary and ethnic differences, etc. The more than 60,000 teeth analyzed in the St. Louis study came mainly from the St. Louis area and were batched to yield a yearly average so that it was not possible to examine the undoubtedly wide individual and geographic variations in levels that would ensue because of variations in rainfall and wind patterns and other factors affecting individuals. Unlike the St. Louis study, technical advances permit RPHP to establish which individuals had significantly above average Sr90 levels, so that follow-up medical evaluation can provide evidence on subsequent health effects. Such a set of medical data would be particularly valuable if it were large enough to reveal significant correlations (or absence) between Sr90 levels and such relatively common childhood illnesses as asthma, obesity , attention deficit disorders, learning disabilities, etc. as well as rare types of childhood cancer. We know that leukemia and thyroid cancer have long been associated with exposure to low-level radiation. Post war data on cancer incidence rates for children aged 0 to 4 from the Connecticut Cancer Registry as revealed below in Figure 2 indicate that there is a close association between consecutive peaks in bomb test exposure, or large scale releases from Connecticut reactors, followed within one or two years by peaks in childhood cancer.
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