Infant mortality rates in San Luis Obispo County in proximity to the Diablo Canyon Nuclear Power Plant.

Radiation and Public Health Project (RPHP) Joseph J. Mangano MPH MBA, April 29, 2026

EXECUTIVE SUMMARY

The two Diablo Canyon nuclear reactors in San Luis Obispo County CA began operations in 1984
and 1985. They have generated enormous amounts of highly radioactive waste. Most is stored at
the site, but some is routinely released into the environment – and into humans through breathing,
food, and water. However, no studies on health effects to the local population have been done.

Exposure to radiation is especially harmful to the fetus and infant. This report analyzes trends and
current patterns of newborn and infant health in San Luis Obispo County, compared to the state of
California. Results show that county rates have shifted from below to above the state:

Infant Deaths. Before Diablo Canyon opened (1968-1984), the county death rate under one year
was 16% below the state. Most recently (2010-2024), the county was 1% above the state, including
11% and 23% higher for white non-Hispanics and white Hispanics.

Premature Births. In the earliest period available (1995-1999), the county rate of premature births
(<36 weeks gestation) was 21% below the state. Most recently (2020-2024), the rate was 3% above
the state (8% and 31% higher for white non-Hispanics and white Hispanics).

Birth Defects. In the period 2016-2024, the county rate of 12 types of birth defects was 114%
greater than (more than double) the state, 3rd highest among the 35 largest California counties.

Other Newborn Health Measures. In addition, the county also has higher current (2016-2024) rates
of common newborn risk factors, including those requiring assisted ventilation, those with low
five-minute Apgar scores (a measure of infant health), and newborns transferred to another facility.

Child Cancer. Child cancer is believed to often be an adverse outcome that began in pregnancy.
Early in Diablo Canyon’s operation (1988-1992), county cancer incidence 0-19 was 26% below
the state; in the 30 years since then (1993-2022), the county rate was just 2% below the state.

No explanation for these findings is apparent, as risk factors in the county are not elevated.
Compared to the state, the county has low rates of minorities, uninsured, foreign born, and
languages other than English spoken at home; and similar rates of income, education, and poverty.
The county rate of the most common maternal birth risk factors are below the state
(overweight/obese mothers, mothers <20 or >35, mothers on WIC or Medicaid, and previous
Cesarean section).

Further review of county health patterns is warranted to assess what role exposures to radioactivity
from Diablo Canyon has played in these trends. Results should be made available to officials and
the public. No major decision on the future of the plant should be made without a thorough
understanding of the impact exposures have had on local health………………………………………………………………………………………………………………………………………………………………………………………………………………………………https://radiation.org/wp-content/uploads/2026/04/Diablo-Canyon-report-November-2025.pdf