Closing a nuclear reactor in California has prevented an estimated 4,319 cases of cancer in the past 20 years, according to a new study released Thursday. Researchers studied the population of the state capitol of Sacramento, an area with more than 1.4 million people living within 25 miles of the Rancho Seco nuclear power plant.
Using 20 years worth of data, researchers found an overall drop in the incidence of all cancers, including six of the 16 most common types. The sharpest drop came within a decade of the plant’s closing in 1989.
“These findings suggest that the closing of Rancho Seco reduced the risk to health for local residents, and provides a basis for conducting analyses on potential long-term health changes,” the study, published in the journal Biomedicine International, states.
Researchers say more work is needed to determine if there’s a cause-and-effect relationship between the reduced incidence of cancer and the closing of the power plant, but they say the data show a statistically significant relationship in several areas.
The most statistically significant reductions were in breast and thyroid cancers in women, two cancers that appeared more frequently in survivors of the nuclear bombs attacks on Hiroshima and Nagasaki during WWII.
A major concern for communities living near nuclear power plants is the effect of radiation on children, as developing fetuses are more susceptible to damage from radioactive isotopes leaked at nuclear sites.
Researchers say that in the first decade after Rancho Seco’s closing, the rate of childhood cancers like leukemia dropped 13.6 percent, while the rate in the rest of the state—the control group for the study—remained unchanged. The cancer rate in Sacramento continued to decline until 2005, when it rose slightly, but it was still below the rate seen in the late 1980s when the plant closed.
Whites and Hispanics—California’s most rapidly-growing ethnic group—saw the most significant drop in cancer rates.
he Rancho Seco power plant closed in June of 1989 following a public vote. The Sacramento area now uses renewable energy to generate 21 percent of its power.