In early 1955, San Francisco 49ers management agreed to make its players guinea pigs in a radiation experiment, according to a series of letters hashing out the “completed arrangements” between the football team and a researcher based at a U.S. Navy lab at Hunters Point.
The men would be injected with radioactive chromium and drink radioactive water, allowing investigators to record precise measurements of various physical traits. But physiology wasn’t Navy Capt. Albert R. Behnke Jr.’s only interest. The physician and renowned scientist wanted to know who was most likely to survive a nuclear war. As he theorized, the grim task of “rescue and survival” after an atomic attack might be left to the exceptionally fit, such as elite athletes.
Though no subsequent report has surfaced in government or academic archives to prove the study was carried out as planned, four decades later one scientist recalled watching the 49ers undergo examinations at the lab.
- 1. OVERVIEW: How a San Francisco Navy Lab Became a Hub for Human Radiation Experiments • List of Studies
- 2. THE DECISION-MAKERS: After Atomic Test Blunder, Government Authorized Study of Radiation in Humans
- 3. THE STUDIES: Human Radiation Studies Included Mock Combat, Skin Tests and a Plan to Inject 49ers
- 4. ETHICS: Cold War Scientists Pushed Ethical Boundaries With Radiation Experiments
- 5. FADING HISTORIES: Destroyed Records, Dying Witnesses Consign San Francisco Radiation Lab to Obscurity
- 6. PERPETUAL EXPERIMENT: Shuttered Radiation Lab Poses Ongoing Health Risks for Growing Neighborhood
- 🎧 Podcast Episode 1: A Community of Color Contends With the Navy’s Toxic Legacy
- 🎧 Podcast Episode 2: Why the Navy Conducted Radiation Experiments on Humans
And decades of other surviving historical documents clearly establish that similar experiments exposed hundreds of less famous people, risking their health without any therapeutic benefit — all with the blessing of the government.
This investigative series details how the U.S. Naval Radiological Defense Laboratory, based at the Hunters Point Naval Shipyard in San Francisco, exposed at least 1,073 dockworkers, military personnel, lab employees and others to radiation in technical exercises and medical experiments early in the Cold War.
A review of thousands of pages of government and academic records by the San Francisco Public Press shows scientists there conducted at least 24 studies exposing humans to radiation from 1946 to 1963, nearly three times more than a federal inquiry acknowledged decades later. Researchers reported dozens of safety violations without any apparent repercussions. There is no evidence the government tracked the long-term effects on study participants, or on residents of the historically African American neighborhood who have long suspected their health problems were connected to pollution from the lab.
In Part 3, we show how the lab’s scientific agenda expanded from monitoring workers’ occupational exposures to using radioactive substances in mock atomic combat and clinical experiments that included topical, oral and intravenous administration of potentially harmful isotopes.
Scientists initiated a diverse slate of studies in and around San Francisco. They gave animals, including sheep, dogs, rats and mice, massive radiation doses to establish how much was lethal. To hundreds of people they administered lower levels, in the laboratory and in the field.
The lab developed what it called synthetic nuclear fallout: dirt or mud laced with a radioactive element that emitted some of the same dangerous energy as the dust and rain that fell on Hiroshima and Nagasaki after the 1945 atomic attacks that ended World War II. The lab exposed hundreds of people to this artificial hazard by spreading tons of radioactive sand and dirt around Army camps in the East Bay in simulations of atomic combat and postattack cleanup efforts, and by testing simple tasks like washing radioactive residue off hands and other body parts.
Lab officials told the Pentagon📄 that they employed “minimal quantities of radioactive tracer material.” At the time, however, rudimentary measuring equipment made dose estimates sketchy guesses.
“The idea that you would use human subjects, and purposefully put radioactive contamination on their skin, supposedly just to test whether soap was better at removing it than other mechanisms, is just extraordinary to me,” said Daniel Hirsch, the retired director of the Program on Environmental and Nuclear Policy at the University of California, Santa Cruz, who has extensively researched the Hunters Point shipyard and the radiation lab located there from 1946 until 1969.
Some of the research was opportunistic. When residents of atolls in the Marshall Islands were poisoned by exposure to fallout from a 1954 hydrogen bomb test, scientists from the San Francisco lab rushed to the isolated Central Pacific archipelago to study them to gain key insights into how radiation and nuclear fallout affect the human body.
All this happened at a time when science’s understanding of the long-term health effects was nearly nonexistent, particularly of the small doses that appear to have been routine in lab experiments.
‘SPECIAL EXAMINATIONS’
A Stanford-trained physician and renowned Navy researcher, Behnke made advances in deep-sea diving and decompression techniques, contributing notably to U.S. submarines’ success in the Pacific during World War II.
In 1953, Behnke was named the radiological medical director of the San Francisco lab, one of the military’s main hubs for researching radiation and its effects on living things. He would work there six years, until his retirement in 1959.
Human experimentation at the lab peaked during Behnke’s tenure, with at least 13 studies carried out in that period, records indicate. Under his leadership, the lab acquired special Atomic Energy Commission permission to expose humans to radioactive elements, both in the field and in the lab.
Scientists obtained licenses📄 to handle weapons-grade plutonium and uranium as well as fission byproducts, including cobalt-60, strontium-90, cesium-137 and iridium-192. The lab also got clearance to use radioactive isotopes with a range of health hazards, such as tritium, potassium-42, bromine-82 and lanthanum-140, in studies involving humans.
Behnke had a valuable opportunity to study what exposure did to people. It was in his mandate: The biological and medical sciences division’s “general aim” was “to learn the nature of radiation injury, how to prevent it, and how to treat it, ultimately in the human,” said an official lab history published in 1958.
Behnke had previously studied body composition — typically by measuring body mass and bone density — using athletes as test subjects but with cruder methods. Using radioactivity to “see” what was inside was cutting edge: quicker, more accurate and, as far as Behnke knew, safe enough.
That was how Behnke pitched the idea to the 49ers. These “special examinations proposed for the football players,” Behnke explained in a series of letters📄 to team physician William O’Grady and general manager Lou Spadia, “will be of mutual benefit” to the lab and to the franchise. All this required was a quick injection of radioactive chromium, a drink of water laced with tritium — a radioactive isotope of hydrogen — and a visit to the lab. The health effects of such a test could well have been minimal. While the use of small quantities of radioactive tracer material is now routine for a variety of diagnostic techniques, the field known as nuclear medicine was then in its infancy and researchers had much less safety data to work with.
In keeping with the lab’s practice of civilian-military cooperation, Behnke was collaborating with William Siri of the University of California, Berkeley. A biophysicist and veteran of the top-secret research and development effort to build the atomic bomb, Siri was also a pioneer in using radioisotopes as a diagnostic tool. In Behnke, he found a kindred spirit and eager colleague.
Behnke had “completed arrangements for the professional foot ball players (49’ers) to serve as subjects here at the Laboratory,” Siri reported in a Jan. 10, 1955, letter to John Lawrence, his boss at the Donner Laboratory at Berkeley. Later lab reports from Behnke also mention earlier body-density tests “on professional football players.”
And Ed Alpen, another former Navy lab scientist, told an oral history interviewer in 1994 that he was in the room in San Francisco when the 49ers had their bodies analyzed. Alpen’s interview📄 was conducted as part of an archival research project at Lawrence Berkeley National Laboratory. Nevertheless, researchers were unable to locate “contemporaneous evidence” confirming that experiments on team members had been conducted.
The 49ers did not respond to several requests seeking comment. The Public Press reached Chris Permann, the son-in-law of 49ers player Hugh McElhenny, before the Hall of Fame halfback died in June 2022. Permann said that McElhenny could not remember any experiment and did not know of anyone else on the 1955 team who was still living.
David Shumway Jones, a professor of the culture of medicine at Harvard’s school of public health, who has researched the history of human experimentation, said he had no reason to doubt Alpen’s memory of events even four decades later.
“There is a justification to say that they did the 49ers study,” he said. “I assume it would have been exciting to do studies on professional football players, so that seems like something a person would remember.”
Other, similar experiments clearly took place.
In a study published in 1959, Behnke and colleagues used radioactive bromine, potassium and other elements as tracers to study at least 35 men of various body types: “healthy men of widely varying degrees of fatness.” Test subjects received no more than 0.2 rad — a measure of absorbed radiation dose — claimed lab Scientific Director Paul Tompkins, Behnke’s civilian counterpart. That is roughly one-third of what the average person absorbs from background, medical and other sources each year.
Though it had little to do with the lab’s central mission, Tompkins played up Behnke’s work📄. “The significance of these studies is far reaching,” he wrote. Doctors could use radioactivity to diagnose diseases and prescribe treatments, even predict health complications before they developed.
Nuclear medicine is now an important part of radiology but not a typical procedure in preventive medicine. And while tracer research was tacked onto the mission of the lab as it ballooned in size and funding, it is still unclear how much it could have helped with preparing for and defending the country from nuclear attack — the founding imperative of the lab.
That was the purpose of the lab’s dirtiest and most dangerous work: simulating the conditions American soldiers and civilians could encounter in a nuclear World War III.
NUCLEAR BATTLEFIELDS
The lab’s genesis was the nuclear testing disaster at Operation Crossroads in 1946, in which the world’s fifth atomic detonation irradiated a fleet of ships and dosed thousands of military personnel. In less than a decade, with the nuclear enterprise opening commercial reactors and even briefly promoting nuclear bombs as useful in civil engineering projects, the lab was close to pivoting from researching weapons effects to “peaceful” pursuits. That all changed on March 1, 1954, in another nuclear catastrophe.
The “Castle Bravo” hydrogen bomb test, at Bikini Atoll in the Marshall Islands, was the strongest-ever nuclear weapon detonated by the United States — 2.5 times more powerful than the scientists who planned it anticipated. Poisonous dust fell on about 300 people, including islanders evicted from their homes to avoid just this scenario and the faraway crew of a Japanese fishing boat.
Researchers from the San Francisco lab rushed to a nearby atoll. They would spend years studying islanders whose exposure provided the bulk of the data quantifying how nuclear fallout affected food, water and the human body.
Castle Bravo also demonstrated that nuclear defense necessitated confronting fallout, a deadly hazard for people living far away from vaporized targets. Understanding this process gave the San Francisco radiation lab new purpose.
“The fall-out problem has become better defined and its importance and ramifications generally recognized,” lab officials stated in their 1954 annual report📄, the document both Pentagon officials and members of Congress would consult when deciding what to pay for, published a few months after Castle Bravo. “Hence, major emphasis will be placed on a continuation and expansion of the investigations and studies in this field.”
Fallout presented very basic questions. For instance, how do you remove it? The lab had experimented with washing radioactive contamination off skin as early as 1949. Initial results were not encouraging. One cleaning method made uptake of radiation worse than simply leaving it to decay on the skin.
Reid Brown / San Francisco Public Press
In 1953, data from a “series of tests on a land target complex at San Bruno” using radioactive dirt — possibly, according to a later study proposal, yttrium-90, an unstable lab-made isotope — had to be ditched. The whole exercise was of “limited value” because the mix bore no resemblance to real fallout, an Army researcher wrote.
Other researchers had hit on using lanthanum-140, an emitter of gamma rays (high-energy photons) and beta particles (fast-moving electrons or positrons). With a half-life of less than two days, it gave off energy that could cause skin burns and, if inhaled, lung and other cancers.
In 1956, Navy scientists obtained lanthanum-140 from a government nuclear reactor in Idaho, flew it to Travis Air Force Base in Solano County in a special plane, and trucked it to Camp Stoneman, an Army installation in Contra Costa County, in a shielded vehicle that used concrete blocks to protect delivery crews. This was mixed into dirt that Army Cpl. Eldridge Jones and his comrades of the 50th Chemical Platoon raked, shoveled and spread to see how nuclear survivors might clean fallout off roofs and roads.
Modern-day experts question every decision made here. “Lanthanum is not going to tell you anything about the several hundred fission products that are present in a bomb,” said Hirsch, the former UC Santa Cruz lecturer. “I don’t understand how they thought at the end of the day those numbers had any meaning whatsoever.”
This concoction proved tricky to handle as well as scientifically worthless. Two soldiers spilled so much radioactive dirt on their hands that nothing could get it all off📄, researcher R.H. Black, one of the synthetic fallout’s inventors, wrote in an article published in the American Industrial Hygiene Association Journal in 1960. And no matter what technique was used, you still needed to scan with a Geiger counter afterward to see if the washing worked. “There is no method yet which has shown itself to be reliable enough in cleaning contaminated hands to be used without the necessity of a radiation check after washing, to comply with peacetime maximum permissible levels,” he concluded.
As for Eldridge Jones’ decontamination work, researchers discovered you could clean fallout off roofs, providing you had an unlimited supply of water and able-bodied crews to do the work — two guarantees you could not make in a postattack scenario.
With the first Stoneman operation’s limitations in mind, the lab and the Army pitched the Pentagon on another fallout test: a mockup of infantry maneuvers through a contaminated nuclear battlefield, to see if soldiers could fight in radioactive conditions.
At Operation Stoneman II📄 in 1958, troops dressed in combat fatigues and gas masks crawled on their bellies through fields of synthetic fallout. They wore film dosimeters so the scientists could record how much radiation ended up on their clothes and skin. The scientists concluded that dedicated laundry and showers, amenities presumably scarce during nuclear combat, were necessary to clean off fallout and minimize burns.
DATA FROM DIRT, AND DIRTY BOMBS
After Stoneman II, lab scientists played with synthetic fallout at least five more times.
Researchers dumped more than 30,000 pounds of sand mixed with barium-140 and lanthanum-140 over Camp Parks, an Army base and the radiation lab’s field headquarters in Dublin, Calif., in November 1959, March 1960 and October 1960. The aim was to test “radiological recovery” techniques to rid land and buildings of fallout.
There is no mention of radiological safety measures for study participants, some of whom also took part in the Stoneman experiments, whose duties included spreading and shoveling the fallout with simple tools including “hand-pulled garden spreaders” in windy conditions that flung the sand into the air.
Images from the series
In echoes of the Operation Crossroads weapons test, in which an underwater bomb left the Navy with a fleet of radioactive ships, San Francisco lab scientists also mixed lanthanum with high explosives to detonate dirty bombs off the West Coast and near the nation’s capital, exposing yet more people to radiation.
First, in Operation Hydra I📄, “every Monday afternoon, for a period of ten consecutive weeks” in the spring of 1959, lanthanum-140 from Oak Ridge National Laboratory was loaded into small bombs and set off in an artificial lake in Washington, D.C., to model how radioactivity would behave in underwater nuclear blasts.
Planners worried that “significant hand exposures may be incurred,” but reported just two instances of personnel contamination, with a maximum whole-body dose of 160 millirem — equivalent to the radiation from 16 chest X-rays — and “both were quickly and easily decontaminated.”
By 1961, the San Francisco lab had gone beyond lanthanum-140 as the isotope of choice. That summer at Operation Hydra II📄, researchers detonated, 13 times, 10,000-pound underwater bombs laced with low-gamma-emitting lutetium-177 and xenon-133 off San Clemente Island near San Diego.
The blasts were designed to create what a report described as an enormous “radioactive water patch immediately surrounding the shot point.” But study authors claimed “no biological problems,” according to the final report completed after the radiation lab closed in 1969.
An unspecified number of study participants received a maximum dose of “less than 40 millirem,” or four chest X-rays, the report said.
Lab officials expressed no concern for the risk to sea life or to Southern Californians who ate seafood or played in the water. The California Fish and Game Commission reported catching one radioactive jack mackerel. Study authors claimed that “this presents no problem,” because any fish caught in the area “will be cleaned” before being eaten by humans.
The lab also burned the skin of volunteers in a series of tests to simulate the injuries suffered by Hiroshima and Nagasaki survivors.
The participants included lab scientists such as Ed Alpen. “I and some of my colleagues were volunteers, who burned ourselves,” he said in his 1994 oral history, “and I carry the scars today.” He added: “It was for a good cause.”
Some of these burn tests also used beta radiation. “Volunteers have exposed themselves to first degree thermal burns and, with the required approval of the Secretary of the Navy, to low-level beta radiation, attempting to add to the small store of data on the human,” the lab reported.
MORE EXPERIMENTS POSSIBLE
There are strong hints that other lab exercises exposed humans, though it may be impossible ever to know for certain.
In one cleaning test, the lab prepared a “solution” that included strontium-90📄, a radioactive fission byproduct, that was mixed with seawater and put onto concrete. Then lab workers tried to clean the surface using various methods, according to a 1958 report. Working with strontium-90 is extremely dangerous: If ingested, it can settle in bones and irradiate surrounding soft tissues for decades. Any exposure humans may have received was not recorded.
For some experts, the synthetic fallout era demonstrates how the San Francisco lab operated with little restraint, purpose or method.
“Here’s a laboratory that acted more like it was searching for things to try, rather than being driven by things that made a lot of sense and were worth the risk,” Hirsch said.
At least once, Pentagon officials stopped the lab from experimenting on more humans.
In the spring of 1959, the lab requested authorization to expand the scope of one of Behnke’s tracer studies to 100 people, including “volunteer patients” in convalescence at the Oak Knoll Naval Hospital in Oakland.
“This Bureau cannot recommend approval of the request to use volunteer patients at the U.S. Naval Hospital, Oakland, California, until such time as the Commanding Officer and Director, U.S. Naval Radiological Defense Laboratory, and the Commanding Officer, U.S. Naval Hospital Oakland, California, shall jointly submit justification for utilization of volunteer patients,” reads a July 28, 1959, memo📄 addressed to Navy Secretary William Franke.
There is no sign the lab tried again.
‘HOT’ SUBJECT
Lab officials rejected another proposal to study humans, calling it politically untenable as well as medically unsound.
In March 1954, lab scientist Myron Silverman wrote to Victor Bond, one of his superiors, who was then in the Marshall Islands. Silverman wanted to give bubonic plague immunizations📄 to islanders who had been exposed to radiation in the Castle Bravo hydrogen bomb test. This would enable him to see what effect the shots would have on an irradiated body compared with a nonirradiated control group. They were already exposed, after all.
But Bond told him no. Silverman’s proposal had no appreciable benefit for the Marshall Islanders. And it would be a bad look for the Americans.
“What happened to them, of course, is a ‘hot’ subject, and what is done must be clearly of medical benefit for them,” Bond wrote📄 to Silverman on April 4, 1954, in a then-secret letter since declassified.
“Anything smacking of using them for ‘guinea pigs’ must be avoided, especially because the Japanese are accusing the U.S.A. of doing this in the ABCC,” he wrote, referring to the Atomic Bomb Casualty Commission, the U.S. government’s study of Hiroshima and Nagasaki survivors.
“It would be easy,” he admitted of the Marshall Islanders in question, “if they were 82 animals rather than human beings.”
Additional reporting by Rebecca Bowe. Listen to Episode 1 and Episode 2 of her podcast.
A series investigating the forgotten history of Cold War San Francisco
The San Francisco Public Press sifted through thousands of pages of obscure records, interviewed experts and tracked down elderly veterans who were subjected to ethically questionable radiation exposure by the U.S. Navy in San Francisco during the Cold War. What we found reveals a troubling history with effects still felt today.
Reporting: Chris Roberts and Rebecca Bowe | Editing: Michael Stoll and Liz Enochs | Research Editing: Ambika Kandasamy | Web Design: John Angelico | Copy Editing: Kurt Aguilar, Michele Anderson and Richard Knee | Archival Research and Illustration: Stacey Carter | Audio Editing: Liana Wilcox, Mel Baker and Megan Maurer | Sound Gathering: Justin Benttinen | Photography: Sharon Wickham, Yesica Prado and Guillermo Hernandez | Graphic Design: Reid Brown | Fact Checking: Dani Solakian and Ali Hanks | Proofreading: Lila LaHood, Noah Arroyo, Zhe Wu and Sylvie Sturm | Special thanks to Alastair Gee and Danielle Renwick at The Guardian and Ben Trefny at KALW Public Radio, and to Laura Wenus and Amy Pyle
Funding for “Exposed” comes from the California Endowment, the Fund for Environmental Journalism, the Local Independent Online News Publishers Association and members of the San Francisco Public Press. Learn more at sfpublicpress.org/donate.
