After scrutinizing thousands of pages of records, we conservatively tallied 1,073 people exposed to radiation in medical and technical experiments conducted by the San Francisco-headquartered U.S. Naval Radiological Defense Laboratory from 1946 to 1963.
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1. Radioactive ship decontamination, 1946-1950. Hundreds of shipyard workers tried to remove plutonium and fission byproducts from vessels irradiated in the first post-World War II nuclear weapons tests. Officials acknowledged the serious risk and imposed controls, including safety equipment like gas masks, despite doubts that they were effective.People exposed: at least 291.Sources:1, 2 and 3.
2. Simulating flash burns from nuclear explosions, 1950s. To mimic the radioactive flash wounds suffered by bomb survivors, an unknown number of volunteers at the lab had “low-level beta radiation” applied to their skin. Some, including lab scientists, also were subject to intense light sources that left scars.People exposed: at least one.Sources:1, 2, 3 and 4.
3. Failed fallout study, 1953. An unknown amount of dirt laced with a radioactive material, possibly yttrium-90, was spread around Navy buildings in San Bruno, Calif., to test decontamination methods, but was found not to be a good facsimile of fallout. An Army study and a lab memo that mentioned this experiment did not specify the number of exercise participants exposed.People exposed: at least one.Sources:1, 2 and 3.
4. 49ers experiment, 1955. With assistance from UC Berkeley, lab scientists planned to give an unknown number of football players with the San Francisco 49ers radioactive water to drink and administer injections of radioactive chromium in “tracer” studies to measure the athletes’ body composition. Lawrence Berkeley Laboratory investigators in the 1990s evaluated correspondence and a scientist’s claim that he witnessed it, though they failed to locate documents proving that the tests were carried out.People exposed: none assumed.Sources:1 and 2.
5. Stoneman I: lotion on hands, 1956. Scores of people, including those who had spread fallout simulant from roofs and fields in the decontamination exercise described above in study No. 3, participated in tests of handwashing methods and preventative techniques like “barrier creams.” Some proved worthless, since soap and water were just as effective, but none assured radiation could be reliably removed in a wartime scenario.People exposed: 188.Sources:1.
6. Stoneman I: fallout on roofs and fields, 1956. Service members and civilian workers spread and cleared radioactive dirt laced with lanthanum-140 from roofs, paths and other surfaces at Camp Stoneman, a decommissioned Army base in Contra Costa County.People exposed: none assumed beyond the 188 referenced in study No. 5, because of probable overlap in participants (but we found at least 15 participated in this one).Sources: 1.
7. Stoneman I: testing skin protection, 1956. Lab scientists rubbed “synthetic radioactive fallout” onto the forearms of “volunteer human subjects” to test nine techniques of removing radiation from bare skin, a pathway identified as a vulnerability in nuclear testing and warfare.People exposed: 45.Sources: 1.
8. Stoneman II: nuclear combat exercise, 1958. Nearly 100 Army soldiers and lab workers either spread synthetic radioactive fallout or crawled through a field of it, in a mockup of infantry maneuvers in a postnuclear-attack fallout zone. The lab reported that four people, all workers mixing the material, received radiation beyond the contemporaneous legal limit for the exercise but were kept on the job.People exposed: 93.Sources:1, 2 and 3.
9. Stoneman II: roof cleaning, 1958. In a follow-up to the 1956 exercise, researchers tested more “land target reclamation” techniques using simulated fallout contaminated with lanthanum-140. Personnel, including members of the Army’s 50th Chemical Platoon, used equipment such as a dispersal truck and hand-operated spreader.People exposed: none assumed beyond the 93 referenced in study No. 8, because of probable overlap in participants (but we found at least 81 participated in this one).Sources: 1 and 2.
10. Potassium measurement in the body, published 1959. Scientists worked out an improved method for measuring potassium levels after an injection of a radioactive isotope of the element.People exposed: one.Sources: 1.
11. Small underwater radioactive explosions, 1959. San Francisco radiation lab researchers set off 31 bombs laced with lanthanum-140 in a Washington, D.C.-area pond to simulate an underwater nuclear blast, in an exercise known as Operation Hydra I. They reported that two exposed workers were “quickly and easily decontaminated.”People exposed: two.Sources: 1.
12. Body water measurements, published 1959. “Healthy men” were given water containing tritium, a radioactive isotope of hydrogen, so scientists could quickly and accurately measure the total amount of body water that can be exchanged with the environment.People exposed: 12.Sources:1.
13. Lean body weight measurements, published 1959. A group of men drank water containing tritium as a tracer for a study of methods to estimate body composition through the measurement of bones.People exposed: 31.Sources:1.
14. Injection in health studies, published 1959. “Healthy men” of varying body types received injections of radioactive bromine, potassium and radioactive water to assess various body metrics.People exposed: 35.Sources:1 and 2.
15, 16, 17. Radioactive sand cleanup, 1959-1960. In three tests at Camp Parks in modern-day Dublin, Calif., workers used hand tools to spread at least 30,000 pounds of sand mixed with barium-140 and lanthanum-140 to simulate wartime “radiological recovery.”People exposed: at least 50 (across multiple tests).Sources:1 and 2.
18. Large underwater radioactive explosions, 1961. In Operation Hydra II, researchers set off 13 explosives off San Clemente Island near San Diego to study the behavior of nuclear weapons detonated underwater. Of those, three with an explosive yield of 10,000 pounds were laced with radioactive lutetium-177 and one with xenon-133. While study authors reported “no biological problems,” they noted exposure of personnel, as well as catching a radioactive fish.People exposed: at least one.Sources:1, 2 and 3.
19. Radiation in the time of cholera, 1961. During a cholera outbreak in the Philippines, San Francisco radiation lab scientists injected an unspecified number of acutely ill patients with radioactive chloride and sodium to monitor patients’ fluid levels.People exposed: at least two.Sources:1, 2 and 3.
20. Underground bunkers, published 1963. Twenty-four men hunkered down in six radiation lab-designed fallout shelters during nuclear weapons tests in Nevada. Three shelters “were in the path of significant fallout.” Scientists could not meaningfully measure how much radiation entered the structures because the men had also brought fallout samples inside.People exposed: 24.Sources:1.
21, 22. Radiation in the streets, 1959-1961. At Camp Parks, the lab experimented with street-cleaning equipment, flushing away sand laced with lanthanum-140 to test its effectiveness in decontaminating public spaces.People exposed: 294.Sources:1 and 2.
23. Hosing down buildings and pavement, 1963. Sand mixed with radioactive lanthanum-140 was dumped on streets and buildings that workers then fire-hosed in a series of three different tests.People exposed: at least one.Sources:1 and 2.
24. Dirty grass, published 1965. Recognizing that “lawns contaminated by fallout from nuclear attack” could not be cleaned like roads or roofs and that grass tended to trap fallout (as the Soviet Union discovered after the 1986 Chernobyl disaster), the lab conducted 12 tests with a commercially available “sod-cutting machine” to remove ground cover contaminated with synthetic fallout.People exposed: at least one.Sources:1.
Caveats: Where participant numbers from scientific studies or technical reports were unavailable, we relied on accounts from oral histories, footnotes from internal memos and interagency letters, some initially marked classified. Where the timeline was unspecified, we provided a publication date. Where no count was documented but human exposure was indicated, we added one person to the total. Where studies appeared to overlap, we included only the higher tally.
This list does not detail the full extent of radiation exposure. Several lab safety reports indicate it was routine, and more than 200 people received dangerously high doses (see upcoming stories in this series for examples).
Almost everyone entering the lab’s headquarters encountered some radiation, but scientists did not carefully track every individual affected. They also did not study how radiation lingering in the nearby environment affected Bayview-Hunters Point neighbors in subsequent decades.