Before We Extend Diablo Canyon, We Owe Our Children Clear Answers
Those of us who live in San Luis Obispo County take pride in our community. We value clean air, open space, strong schools and a safe place to raise children. That is part of what makes this region special. It is why so many of us chose to live here and why we work to protect what we have.
Which is why repeated public health warnings deserve careful attention — not dismissal.
Concerns about health impacts near Diablo Canyon are not new. A March 2, 2014 report titled “Report on Health Status of Residents in San Luis Obispo and Santa Barbara Counties Living Near the Diablo Canyon Nuclear Reactors” by Joseph Mangano, MPH, MBA, examined cancer and other health indicators in communities closest to the plant. That report identified elevated rates of certain cancers and recommended continued monitoring and further study. More than a decade later, comprehensive long-term health monitoring still has not occurred.
Recent research strengthens those concerns.
In December 2025, Harvard University published a study, “Residential proximity to nuclear power plants and cancer incidence in Massachusetts, USA (2000–2018)”, which examined cancer incidence near nuclear power plants in Massachusetts. Researchers found elevated cancer risks among residents living closer to reactors, particularly older adults, and documented that risk declined with distance. The authors emphasized the importance of continued epidemiologic monitoring as reactors age and licenses are extended.
That study did not focus on California. But its findings reinforce concerns raised here at home.
A peer-reviewed study published November 12, 2025, “Worsening Infant Health in San Luis Obispo County and the Diablo Canyon Nuclear Reactors,” by Joseph Mangano, MPH, MBA, examined long-term local health trends. It found that outcomes once better here than the California average have steadily eroded.
Before Diablo Canyon began operating, our county’s infant mortality rate was 16 percent lower than the state average. Now, that advantage has disappeared. Premature births, once well below the state rate, rose above it. Birth defect rates in recent years were more than double the California average, ranking third highest among large counties. Childhood cancer rates, once significantly lower than statewide levels, have moved closer to them.
These are not one-year spikes. They are long-term trend changes. And they matter because they affect our youngest and most vulnerable residents.
Taken together, the 2014 and 2025 Mangano studies and the recent Harvard findings point in the same direction: communities living near operating nuclear reactors deserve rigorous, transparent and ongoing health evaluation. When warning signals appear across different studies, time periods and states, the responsible response is investigation.
San Luis Obispo County does not fit the profile of a community struggling with the usual drivers of poor birth outcomes. We have relatively low poverty and unemployment, high education and income levels and good access to medical care. Many known risk factors are lower here than statewide. Yet our early-life health advantage has faded.
No one is claiming these findings prove cause and effect. But public health protection does not require absolute proof before asking serious questions, especially when children’s health is involved.
Before any extension moves forward, San Luis Obispo County deserves an independent, site-specific public health assessment conducted transparently and reviewed publicly. That is not anti-nuclear. It is pro-accountability — and it is what our children, grandchildren, great-grandchildren and all future generations deserve.
If we are considering operating Diablo Canyon for another 20 years, we must first really know what the last 40 years have meant for the health of families who live here. How many premature births, birth defects, childhood and adult cancers are we willing to accept if Diablo Canyon continues running for another twenty years?