LIMERICK NUCLEAR REACTOR EMISSIONS
AND THE POTENTIAL LINK TO LOCAL CANCER RATES

1. Limerick History and Percent Time in Operation
The Limerick nuclear power plant consists of two reactors. Both were announced by the PECO company in 1969; but because of construction delays and public opposition, much time elapsed before the plant began producing electricity. Limerick Unit 1 achieved initial criticality (began producing nuclear power, at limited capacity) on December 22, 1984, while Limerick Unit 2 went critical on August 1, 1989. Each has a license to operate for 40 years from the U.S. Nuclear Regulatory Commission (NRC).

In their first years of operation, the Limerick reactors were closed fairly frequently due to mechanical problems. But from 1999-2005, the reactors were operational 96.7% and 96.3% of the time, according to the NRC (data through February 2005). While the economic benefits of high operating rates are clear, the question of whether running aging reactors more of the time is also raised.

2. Philadelphia Region Has Most Reactors in U.S.
The Limerick plant lies about 21 miles northwest of central Philadelphia. But 13 nuclear reactors are within 90 miles of the city (see Table 1). The Philadelphia area has the largest concentration of nuclear reactors in the U.S., along with northern Illinois.

3. Environmental Levels of Radiation
The U.S. Environmental Protection Agency measures levels of radioactivity in the air, water, precipitation, and milk in various stations around the U.S. The station closest to Limerick is Wilmington DE, about 30 miles to the southeast. One measure that approximates total radioactivity is gross beta in precipitation, measured each month. Gross beta refers to all radioactive chemicals that emit beta particles vs. alpha particles or gamma rays.

During the 1990s, the average concentration in gross beta in Wilmington was 2.11 picocuries per liter of precipitation. But in the period 2000-2003, the average had risen to 2.43 picocuries. Thus, environmental radioactivity in precipitation rose 15.2% from the 1990s to the 2000s, and the question of whether additional radioactivity from operating reactors more frequently is raised.

4. In-Body Levels of Radiation
In 1998, the Radiation and Public Health Project (RPHP), a professional research group, began the only large-scale program measuring radioactivity levels in the bodies of persons living near nuclear reactors. The Tooth Fairy Project was designed to collect baby teeth and measure concentrations of Strontium-90, a chemical produced only in nuclear weapons and reactors. The study was structured similar to a 1960s study by Washington University in St. Louis, measuring Sr-90 levels in teeth from atomic bomb test fallout.

RPHP has collected and tested over 4,400 baby teeth, and has published its findings in four medical journals. Most teeth are from areas near seven nuclear plants in six states, including Limerick. Pennsylvania residents donated 150 teeth to the study. To date, Pennsylvania has the highest Sr-90 levels in baby teeth of any state, and the Limerick area has the highest Sr-90 levels near any nuclear plant.

Other important findings include a rise of 26.2% in average Sr-90 concentration in the baby teeth of children living in Berks, Chester, and Montgomery Counties (closest to Limerick) from 1986-91 to 1992-96. The rise in Sr-90 in baby teeth correspond to the period of greater use of the aging Limerick reactors, and higher local levels of environmental radiation.

Average Sr-90 levels also vary by distance from Limerick. Children in Pottstown had an average level of 5.70 picocuries of Sr-90 per gram of calcium, compared to 4.21 in the rest of the tri-county area, and 3.27 in the Philadelphia region (Table 2). Still, the 19 teeth from Philadelphia children were comparable to areas near reactors in other states.

5. Increases in Cancer Rates in Local Children After Limerick Startup
Even though radiation exposure affects all humans, it is most harmful to the developing fetus, infant, and small child. Cells divide more rapidly early in life, and a cell damaged by radiation is more likely to duplicate in a fetus, infant, or child. In addition, the immune system is still underdeveloped in early stages of growth.

Previous studies in radiated populations show that children can begin to develop additional cancers several years after exposure. Thus, an examination of childhood cancer rates near Limerick before and after the plant began operations is in order. Table 3 compares cancer death rates for children under age 15 for 1984-1990 and 1991-2002. Childhood cancer mortality increased in both Montgomery and Philadelphia counties for leukemia (16.0% and 46.4%) and all cancers (48.0% and 22.3%). During the same period, national rates of childhood cancer deaths dropped sharply, making these findings significant. Childhood cancer in the two counties went from below to well above national rates after Limerick startup.

Cancer incidence in children under 15 can also be tracked beginning in the early years of Limerick operation. Since the late 1980s, both Montgomery and Philadelphia County cancer rates have only increased minimally (up 4.5% and 2.2%, respectively). But rises in leukemia incidence has soared 27.7% and 47.5%, compared to a national decline of 0.7% (Table 4).

6. Philadelphia Cancer Death Rate Highest of 60 Most Populated Counties
In addition to children, adults can be harmed by radiation exposures like emissions from nuclear plants. While the lag between exposure and cancer may take decades in adults, it is useful to examine local cancer rates. For the most recent period (1999-2002, or nearly two decades since Limerick began operations), the total cancer death rate for Philadelphia County was compared with rates for the 60 most populated counties in the U.S., all of which had at least 790,000 residents as of July 1, 2003. A total of 95,857,114 persons, or about one-third of all Americans, live in these areas.

Table 5 shows that of the 60 most populated counties, Philadelphia has the highest cancer death rate from 1999-2002. It ranks highest for whites, and third highest for blacks. Its rate of 254.9 deaths per 100,000 persons is 26% higher than the U.S. rate. Table 6 and 7 show that for each age group in whites and blacks, the Philadelphia cancer death rate exceeds the national rate. While radiation exposure may be only one factor in these patterns, it nonetheless should be considered as a potential contributor.