Radioactive contamination still haunts Hunters Point in San Francisco

san francisco – More than half a century after the United States fired 67 nuclear warheads in the central Pacific, a former naval base in the Gulf region continues that nuclear legacy.

Last week, residents were notified by the San Francisco Health Department that tests taken in November 2024 at the former Hunters Point Naval Shipyard site showed that levels of plutonium-239 radiation from the air exceeded the Navy’s “action level,” requiring the military to investigate further.

The city and residents were not aware of this initial reading for 11 months.

Hunters Point, a 500-acre peninsula in San Francisco Bay, served as a military laboratory to study the effects of nuclear weapons from 1946-69 after World War II. Although research has largely focused on decontaminating US warships and equipment targeted with atomic bombs, the experiment left much of the ship contaminated with radioactive contaminants and toxic chemicals.

For the past 30 years, the Navy has sought to clean up the area — now a U.S. Superfund site — with the long-term goal of developing it into new housing and parkland.

But some Bay Area leaders say the hasty remedial work and lack of public awareness have put the health and safety of residents in the Bayview-Hunters Point neighborhood, which sits next to the former shipwreck, at risk. And they point to the Navy’s nearly one-year delay in notifying them of the enhanced plutonium-239 readings, taken in November 2024, as just one recent example.

Plutonium-239 is a radioactive isotope and a byproduct of nuclear bomb explosions. The highest reading from November 2024 came from a 78-acre plot in the northeastern part of the ship, known as Parcel C.

“The City and County of San Francisco are deeply concerned by the severity of this outbreak and the failure to provide timely notification,” San Francisco Health Officer Susan Philip wrote in an Oct. 30 letter to Navy officials. “Such delays undermine our ability to protect public health and maintain transparency. Prompt notification is a regulatory requirement and critical to ensuring public trust and safety.”

Marine officials and some health experts insist that the radiation levels detected at the site, while above marine action levels, do not pose an imminent or significant threat to public health. A daily exposure to plutonium-239 for a year would be less than one-tenth the radiation from a chest X-ray, according to a Navy spokesman.

“The letter from the San Francisco Department of Public Health refers to a single outdoor air sample that detected plutonium-239 above the regulatory action level,” a Navy spokesman said in a statement to The Times. “The regulatory action level was deliberately and conservatively established below the health concern level, and a single detection of Pu-239 at this level does not pose a risk to human health or public safety.”

The Navy said it has collected more than 200 air monitoring samples from Parcel C since it began field work there in 2023. The November 2024 sample was the only reading with enriched plutonium-239, a Navy spokesman told The Times.

The plutonium isotope emits alpha radiation which is relatively mild outside the body, as it cannot travel through solid matter. However, if these radioactive particles are inhaled, they can damage the lungs and increase the long-term risk of developing certain cancers, according to the Centers for Disease Control and Prevention.

“What we’re concerned about in general with alpha emitters is if you get them into your body, either through inhalation, ingestion, accidental injection — like someone gets cut and it gets into their body,” said Kathryn Higley, a professor of nuclear science at Oregon State University.

But it is the lack of transparency and the 11-month delay in reporting the readout that has fueled public distrust and raised questions about the military’s ability to clean up the contaminated ship. In 2000, the EPA warned marine officials that they had neglected to notify residents that a hazardous land fire had broken out at Hunters Point. In 2017, two employees of the consulting firm Tetra Tech, which was hired by the Navy to assess radiation levels at Hunters Point, pleaded guilty to falsifying data in an attempt to avoid additional cleanup in parts of the shipyard.

The presence of radioactive air pollutants — at any level — compounds the health risks of the Bayview-Hunters Point neighborhood, which is already exposed to toxic diesel particulates from big rigs traveling on highways and cargo ships near San Francisco’s port.

The Hunters Point Biomonitoring Foundation, a local nonprofit, found levels of toxins in urine screenings it provided to many neighborhood residents, particularly among the elderly and those living near the former shipyard.

“Now, you’re talking about adding one of the most destructive radionuclides known to the human cardiovascular system to a chemical burden,” said Dr. Ahisa Porter Simchai, the foundation’s medical director and principal investigator.

“The particle load is enough to kill people,” Somchai added. “But you add … a little Plutonium-239, and it’s a recipe for death.”

Phillips, the San Francisco health officer, said in a statement that she met with Navy officials on Oct. 31 to ensure that air and dust monitoring is “ongoing” and that the military is “reviewing their duct control methods to ensure they fully protect public health.”

As a result, “no immediate action is needed from a public health safety perspective,” she said, adding that her office will monitor the situation closely.

Other experts argued that the situation has worsened. Phil Rutherford, a radiological risk expert and corporate consultant, called the delayed notification “acceptable” but said the letter from the San Francisco Health Department was a “tempest in tea” given the low levels of radioactivity.

Higley, the Oregon State professor, said the site’s long history has added to the potential for delays and scandals from community members. “I understand [residents’] “Higley said they want to see the site clean so they can use it safely. But, from a radiological perspective, the actual residual radioactivity at the site is very little,” Higley said.

In November 2024, a Navy contractor was grinding asphalt at the site — a construction project that, while unrelated to the site’s historic contamination, prompted the Navy to monitor air quality issues. One of those air samples, in Parcel C – collected 8.16 times 10-15 picocuries per milliliter of plutonium-239 – twice the established action level – according to a Navy spokesman.

Navy officials sent the sample to a lab for analysis, and preliminary results came back in March 2025, showing high levels of radiation. In April, they ordered the lab to reanalyze the sample. In a follow-up analysis, the plutonium-239 radiation level was below the action level.

Between May and September, the Navy “further reviewed the test results and conducted a methodical review of the laboratory’s procedures and practices to ensure they were compliant with standards,” according to a Navy spokesman. “A third party also performed a laboratory performance analysis.”

Later in September, the Navy told the US Environmental Protection Agency and several California state agencies about high levels of airborne radiation from Plutonium-239, in preparation for an upcoming community meeting. This information was later sent to the San Francisco Health Department.

At one point, the Navy released some of the air quality data for Parcel C collected between October and December 2024 on a website where it provides several environmental monitoring reports. This report only indicated that the low levels of plutonium-239 radiation from the reanalysis were below the action level.

A Navy spokesman told the Times that it was “uploaded by mistake.”

“When the Navy realized that an incomplete report had been uploaded, it was removed from the website,” the spokesman said, while the Navy worked to verify the results.

All of which contributed to confusion and anxiety among the locals and defenders. Navy officials are expected to attend a Nov. 17 meeting of the Hunters Point Shipyard Citizens Advisory Committee.

When field work is done on the ship’s surface, the Navy monitors for plutonium-239 and several other radioactive elements that may be a historical byproduct of nuclear weapons testing.

Acquired by the Navy in 1940, Hunters Point was initially a base where ships were built, repaired and maintained during World War II. After the war ended, it became the home of the Naval Radiological Defense Laboratory, a military research center dedicated to investigating the effects of nuclear weapons and radiological safety.

The Navy bombarded US warships with nuclear weapons as part of a nuclear test in the Marshall Islands. The irradiated vessels were taken to Hunters Point and used as materials and hardware on which scientists tested cleaning methods.

In 1974, the shipyard became inactive. Hazardous chemicals and low-level radiological contamination were identified, prompting the US EPA to place the site on its Superfund list in 1989.

The Navy led the cleanup effort, excavating contaminated soil and destroying buildings. The base’s largely residential parcel, Parcel A, was moved to San Francisco and redeveloped with new townhouses and condos. A group of 300 artists live and work in former naval buildings.

But risks are emerging during the ongoing restoration work.

In recent years, the Navy has acquired radioactive materials, including dials and deck markers coated with paint containing radium isotopes to provide a glow-in-the-dark effect. Samchai, the medical director of the Biomonitoring Foundation, said she had seen large deposits of contaminated soil without any protective fencing to prevent contamination from leaving the site.

“I see this as a local public health emergency,” Simchai said. “I think everything should be done to contain it and remove people safely, if necessary, from documented areas of exposure.”

But to the casual observer the site looks unremarkable.

Hunters Point overlooks the San Francisco Bay just north of where Candlestick Park, the former home of the San Francisco Giants and 49ers, was. Beyond the abandoned barracks and dry docks, the site is now a mostly empty expanse of grass and weeds, with an unobstructed view of the bay.

The clearing sites, including Parcel C, are still closed, and only those with valid documents are allowed on the property.

On a recent weekday afternoon, pigeons flew and swarmed the long-vacant shipyard buildings, while construction workers and trucks hauled building equipment up and down Hill Drive — a steep road leading to new homes that stood guard over the former shipyard.

And beyond waiting for a new batch of Navy reports, there was no way of knowing what was in the air.