Saturday, May 10, 2008

Strontium 90 in Baby Teeth near Nuclear Reactor

published by WISE/NIRS Nuclear Monitor on May 16, 2003
U.S.: strontium-90 in baby teeth near Florida reactors

A study on childhood cancer near nuclear power plants in Florida, U.S., was released in April. According to the study by the Radiation and Public Health Project, levels of fission product strontium-90 in the teeth of children living in southeast Florida had increased with 37% from 1986-1989 to 1994-1997. The highest levels were found near the Turkey Point and St. Lucie reactors. The amount of radioactive strontium-90 appeared to be 85% higher in the teeth of children with cancer than those without. The results might suggest a link between cancer and exposures to radioactivity from the reactors, but further studies are still needed to confirm this.

(587.5518) WISE Amsterdam - The study was conducted by the Radiation and Public Health Project (RPHP) and funded by the Health Foundation of South Florida. RHPH is an independent non-profit research organization, established by scientists and physicians to investigate the links between environmental radiation, cancer and public health. The main authors of the study are Dr. Ernest Sternglass, Professor Emiritus Radiation Physics of the Unversity of Pittsburgh, Dr. Jerry Brown, Founding Professor Florida International University and Joseph Mangano, national coordinator of RPHP.

Four nuclear reactors are in operation in southeast Florida: Turkey Point-3 and -4 in Miami-Dade County and St. Lucie-1 and -2 in St. Lucie County. Concerns have been raised about reported increases in childhood cancer. RPHP studied data on radioactive releases from the plants, radioactivity concentrations in rain- and drinking water, cancer rates in the region and levels of strontium-90 in baby's teeth in the region. The main findings of the RPHP study are:

Radioactivity emissions

Radioactivity in Miami-Dade County (Turkey Point) rainwater rose from a minimum in 1987-1988 to a plateau in 1990-1993, and later by some 60% in the last half of the 1990s. Atmospheric bomb testing by the U.S. ended in 1963 and by other countries in 1980. Accidental releases by underground bomb testing ended in 1992-1993. The releases by these test were an important source of beta-emitting radionuclides. As the activity in water still increased in the late 1990s, the persistence of (high beta) radioactivity in precipitation and drinking water near Turkey Point and St. Lucie therefore is likely to be caused by those two NPPs.

Radioactivity in drinking water

The highest levels of fission product strontium-90 in drinking water in southeast Florida were found within 5-20 miles (8-32 kilometers) of the Turkey Point and St. Lucie reactors. Fission products like strontium-90, cesium-137 and iodine-131 are always released during normal operation of a reactor. The are released by the plant by air or water discharges. The levels of strontium-90 decreased with distance from the plants. This appears to rule out past nuclear bomb tests as the source of strontium-90 in drinking water. Contamination by nuclear tests would have caused equal activity levels all over Florida instead of the highest levels found near the two NPPs.

Cancer rates in Southeast Florida

From the early 1980s to the late 1990s, cancer incidence in children under 10 rose 35.2% in the five counties closest to the Turkey Point and St. Lucie reactors. Childhood cancer in the whole U.S. had only risen with 10.8%. So, the amount of childhood cancer rose more quickly in the regions of the two NPPs. A high amount of 325.3% increase in childhood cancer was observed in St. Lucie County.

Radioactivity in Florida Baby Teeth

The authors collected baby teeth for measurements on strontium-90 concentrations. The study found that levels of strontium-90 in 250 Miami-Dade County baby teeth have been rising since the early 1980s. The current level is even as high as in the late 1950s, when the U.S., U.K., and the Soviet Union conducted atmospheric bomb tests. As the major releases of strontium-90 have ended since the atmospheric tests stopped, the authors suspect another cause for the (increased) presence of strontium-90 in teeth.
A comparison of the 461 baby teeth from six southeast counties near the two NPPs with 24 teeth from 12 other Florida counties (more than 40 miles from any NPP) showed that strontium-90 levels in the six southeast counties have a significant 44% higher concentration of strontium-90.

In 1982, the average concentration of strontium-90 in southeast Florida baby teeth was 2.23 picoCuries per gram Calcium. By 1995, it reached 5.29 picoCurie/g Calcium. That significant rise of +137% makes it almost impossible to ascribe the current levels to past atmospheric nuclear bomb tests. That is because of the fact that one would expect a decline in strontium-90 levels as the atmospheric tests had ended and strontium-90 from that cause is more and more disappearing from the natural environment.
From 17 teeth from children diagnosed with cancer and living in the counties near the NPPs, 14 were found to have strontium-90 levels above the average for those without cancer in the same counties. Furthermore, 11 out of these 14 teeth have significantly higher strontium-90 concentrations. On average, strontium-90 levels in cancer teeth were 85% higher than those found in non-cancer teeth.

Conclusions and recommendations

The authors conclude that the radioactivity releases from the Turkey Point and St. Lucie NPPs are the primary cause of rising strontium-90 levels in southeast Florida baby teeth, which is the highest in the counties near the plants.

Strontium-90 levels are significantly higher in teeth from children with cancer. The higher levels of strontium-90 in children with cancer raises the question whether exposure to emissions by the two NPPs may be a possible cause for the cancer. The authors are quite strong in their conclusions when they state that "there is now substantial evidence that exposure [...] is a significant causal factor". But as this is only a first study on strontium-90 levels in Florida they also recommend that more detailed studies on cancer rates and a relation with strontium-90 levels are necessary before full conclusions can be drawn.

The possible radiation-cancer link should also be considered in future federal policies regulating the operation of nuclear reactors, especially on renewal or extension of the licenses of aging reactors.

More information about the Radiation and Public Health Project can be found at their website: The website also includes earlier study results of the project.

1. Environmental Radiation from Nuclear Reactors and Childhood Cancer in Southeast Florida, Radiation and Public Health Project, 9 April 2003
2. Press release RPHP, 9 April 2003
Contact: J. Mangano, National Coordinator, RPHP, 786 Carroll Street, Brooklyn, NY 11215, U.S.
Tel: +1 718 857 9825