For San Francisco residents, October 11, 1950, began like any other day, with a thick autumn fog rolling in from the Bay Area and across the city. However, by midday, it was clear something was seriously wrong. That day alone, eleven patients were admitted to Stanford Hospital with pneumonia, fever, and severe urinary tract infections. One of them, a 75-year-old retired pipefitter named Edward J. Nevin, died three weeks later. Tests revealed that the culprit was Serratia marcescens , a bacterium so rare that no cases had ever been recorded in San Francisco. Hospital doctors were so puzzled by this unusual cluster of infections that they reported the incident in a medical journal, though when no new cases emerged, they dismissed it as a fluke. But what the doctors and residents of San Francisco didn't know was that the thick fog that blanketed the city that fall had brought with it a secret passenger: trillions of bacteria, sprayed from a Navy ship sailing offshore. This operation, codenamed «Sea Spray» It was part of a top-secret Cold War project designed to test the city's vulnerability to a potential Soviet biological weapons attack. But San Francisco was far from alone; between 1949 and 1969, the US military deliberately exposed dozens of American cities and millions of ordinary citizens to potentially harmful bacteria and chemicals, all in the name of national security. This is the shocking story of one of the largest human experimentation programs in American history.
Biological warfare has long been a part of human conflict, from the medieval practice of catapulting infected corpses and rats into besieged cities to spread disease to the infamous use of smallpox-infected blankets during the 18th-century French and Indian War. But it wasn't until the late 19th century, when scientists like Robert Koch and Louis Pasteur discovered the microorganisms that cause diseases and how to cultivate them, that the development of specifically effective biological weapons began in earnest. By the time of World War I, Imperial Germany had developed an extensive biological weapons program, perfecting strains of anthrax and glanders with which it planned to infect its enemies' livestock and military draft animals. However, none of these weapons were ever used before the war ended. But the horrific effects of chemical weapons, which was used during the war – such as phosgene and mustard gas – made such an impression on world leaders that in 1925, 146 countries came together to develop Geneva Protocol for the Prohibition of the Use of Asphyxiating, Poisonous and Other Gases and Bacteriological Methods of Warfare. The treaty was signed by 38 countries, including France, Britain, the Soviet Union, Japan, and the United States, although the latter two did not ratify it until the 1970s.
Over the next two decades, most countries signatory to the Geneva Protocol avoided developing biological weapons—with one notable exception. In 1936, the Imperial Japanese Army established a biological warfare research facility near the Chinese city of Harbin, in the Japanese puppet state of Manchukuo. Run by General Shiro Ishii, the facility, known as Unit 731, would go on to commit some of the most horrific atrocities in modern history. In experiments that make the work of Nazi scientists like Dr. Josef Mengele look like the pinnacle of medical ethics, Unit 731 researchers used local Chinese citizens as guinea pigs, exposing them to deadly pathogens such as anthrax and bubonic plague before dissecting them alive without exposing them to anesthetic to study the effects of these diseases. Japanese planes also dropped bombs containing anthrax, plague, cholera, salmonella, and other pathogens on 11 Chinese cities, killing tens of thousands of people.
While such horrors may seem unique to Imperial Japan's extreme militarism, Western powers soon succumbed to the dark allure of biological warfare. Following the Nazi invasion of Poland in September 1939, the United Kingdom established its own biological warfare program, based at Porton Down in Wiltshire and Toronto, Canada. Research focused on the weaponization of tularemia, ornithosis, brucellosis, Q fever, and anthrax—and more on this in our previous video. «Grosse Ile - Canada's Anthrax Island.
The Japanese attack on Pearl Harbor on December 7, 1941, also forced the United States to change its stance on biological warfare. In early 1942, US Secretary of War Henry Stimson expressed concern to President Franklin D. Roosevelt about America's vulnerability to biological attack. In response to this and growing pressure from Britain, in November 1942, Roosevelt approved the creation of a US biological weapons program under the control of the US Army Chemical Warfare Service and centered at Fort Detrick, Maryland. By 1945, the US biological warfare program had succeeded in producing several tons of disease-causing pathogens, including anthrax and smallpox, although none were ever used in combat. American wartime policy dictated that such weapons were to be used only as retaliation or as a deterrent against enemy biological attacks, and in this, the program was highly successful; After the war, captured documents showed that fear of American retaliation convinced Nazi Germany to abandon its own biological weapons program.
The onset of the Cold War brought a new sense of urgency to the US biological weapons program, as intelligence obtained by the CIA revealed the existence of a vast Soviet biological weapons research program based in the city of Sverdlovsk in the Ural Mountains. Desperate to gain some advantage over the Soviets, the US government went so far as to pardon the scientists of Japan's Unit 731 in exchange for their data and expertise. Yet, despite Japan's extensive real-world experience with biological warfare, many questions remain: Which pathogens would cause the most damage? Which dispersal method was most effective? How would pathogens spread in cities versus rural areas? Which Soviet and American cities were most vulnerable to biological attack, and how could the latter be protected? To answer these questions, three potential methods were evaluated: first, small-scale testing using model cities in wind tunnels; second, full-scale testing using live pathogens in simulated cities; And third, full-scale testing using simulated pathogens in real cities. Although wind tunnel tests conducted by the British yielded some useful results, the first two methods were quickly rejected: the first due to its technical limitations, and the second due to the prohibitive cost of simulating an entire city. This left method number three: releasing simulated pathogens in real cities. Thus, the search began for American cities that could closely approximate Soviet population centers.
This proved more challenging than expected, as most of the regions that matched the cities in temperature and precipitation did not match them geographically—and vice versa. Ultimately, however, eight cities were found to have the desired combination of climate, geography, and architecture: Oklahoma City, Kansas City, Omaha, Cincinnati, St. Louis, Chicago, and Winnipeg in Canada—with Minneapolis, St. Louis, and Winnipeg deemed particularly suitable. Cities in California and Florida were also selected for coastal testing. To simulate the biological warfare agents, the researchers selected four different bacterial species: Serratia marcescens, Bacillus globigii, Bacillus subtilis и Aspergillus fumigatus. Selected for their similarity to real biological agents such as anthrax and tularemia, these bacteria are also readily found in nature and easy to grow—indeed, Serratia marcescens It is responsible for the pink film that often grows in bathtubs and toilets. Chemical simulants were also used, including zinc cadmium sulfide, a powder whose small particle size and fluorescent glow made it ideal for tracking the spread of infectious agents through the air. At the time, all of these simulants were considered harmless to humans. However, for safety reasons and to ensure the most accurate results, residents of the target cities would not be informed of the tests. Thus began one of the most ethically charged chapters in the history of American military research.
The first biological weapons test on U.S. soil took place in August 1949, when Special Operations agents at Camp Detrick released inert bacteria into the Pentagon's ventilation system. Larger operations soon followed, including Operation Sea Spray. Between September 20 and 27, 1950, a US Navy minesweeper was sailing near San Francisco Bay, spraying a mixture Serratia marcescens и Bacillus globigii from large on-board hoses. Meanwhile, 43 monitoring stations across the city recorded the spread of bacteria. According to Leonard J. Cole, author of the book «Clouds of Mystery» , the data showed that:
«"Almost all of San Francisco received 500 particles per liter. In other words, nearly every one of the 800,000 people in San Francisco exposed to the clouds at a normal breathing rate (10 liters per minute) inhaled 5,000 or more particles per minute for the several hours they remained in the air.".
Similar tests were conducted off the coasts of South Carolina, Georgia and Florida, and between 1953 and 1975, Britain's Chemical Defence Experimental Establishment at Porton Down conducted biological warfare experiments in Dorset, spraying a mixture of zinc sulphide, cadmium and Bacillus globigii . coast of South West England.
In 1965, as part of the Pentagon's Project 112, American researchers released Bacillus globigii at National Airport and the Greyhound Terminal in Washington, D.C. More than 130 passengers were infected, causing the bacteria to spread to 39 cities in seven states over the next two weeks. The following year Bacillus Subtilis was released into the New York City subway system by dropping bacteria-infested lightbulbs onto the tracks. These bacteria also spread rapidly along the subway lines, leading to the conclusion in the official Army report on the experiment:
«"Such stealthy attacks using a pathogenic disease-causing agent during peak periods can be expected to expose large numbers of people to infection and subsequent illness or death.".
However, the largest of these experiments was Operation LAC, which took place between 1957 and 1958. Short for "wide area coverage," LAC assessed the feasibility of covering large areas with biological warfare agents by releasing them from aircraft. Using a Fairchild C-119 Flying Boxcar cargo aircraft, LAC dropped hundreds of tons of zinc cadmium sulfide over 33 rural and urban areas in the Midwestern United States and Canada, while ground stations monitored the spread of the fluorescent powder. Tests demonstrated that the aerial dispersal method was extremely effective, with the simulant traveling up to 1,900 kilometers from the release site.
As shown in our previous videos «"That time, American scientists injected plutonium into people without their knowledge."» и «The Horrific Tuskegee Syphilis Experiment, Human medical experiments in the United States typically have a strong racial component and often target poor Black communities and other vulnerable groups. Operation LAC was no exception. Beginning in the mid-1950s, the Army began spraying zinc cadmium sulfide powder using motorized blowers mounted on top of Pruitt-Igoe, a massive housing project in St. Louis populated almost entirely by poor Black residents. As part of the Army Chemical Corps' St. Joe program, the simulant was also sprayed from airplanes and trucks in St. Louis, Minneapolis, and Winnipeg—again, primarily in poorer neighborhoods. Because the sprayers were difficult to hide, residents were told they were creating an invisible smokescreen that would protect the cities from Soviet radar.
Between 1949 and 1969, the U.S. military conducted a total of 239 open-air biological warfare experiments in 66 cities across America and Canada, 80 of which used live bacteria. The program was halted only by President Richard Nixon's 1969 directive calling for the destruction of all U.S. biological warfare agent stockpiles, which were completed by 1973. The biological weapons experiments would be destroyed along with the weapons themselves. In 1976, a reporter Newsweek Drew Fetherston discovered classified documents revealing many of the secret tests. This, in turn, prompted San Francisco Chronicle disclose and report experiments as part of Operation Sea Spray« , conducted in September 1950. In light of these revelations, in 1977 the federal government formed U.S. Senate Subcommittee on Health and Research to investigate allegations of experimentation.
Although the US Army believed that the biological warfare simulators used it in their live experiments were harmless to humans, it is now known that in large enough doses Serratia marcescens и Bacillus globigii can cause serious infections. Indeed, it is now believed that the release of these bacteria over San Francisco permanently altered the region's microbiome, leading to an epidemic of heart valve infections in hospitals and other serious infections among intravenous drug users throughout the 1960s and 1970s. And in 2004, a number of infections caused by the flu vaccine were linked to Serratia marcescens at the Chiron Corporation plant in Alameda, California. However, it is now believed that 11 cases of urinary tract infections caused by Serratia marcescens , which took place on October 11, 1950, were not related to Operation Sea Spray. As Army officials testified at a 1977 Senate hearing, all 11 patients had recently undergone minor surgeries, and the outbreak was confined to a single hospital, indicating that the source of the infection was within the hospital itself. However, in 1977, the surviving family members of Edward J. Nevin, who allegedly died as a result of the 1950 experiments, sued the federal government for negligence and financial and emotional damages, with Nevin's grandson, Edward J. Nevin III, stating:
«"If it weren't for this, my grandfather wouldn't have died and my grandmother would have gone broke trying to pay his medical bills.".
Unfortunately, the U.S. District Court in San Francisco ruled against the Nevins, declaring there was insufficient evidence that the bacteria used in the test were responsible for the death of Edward J. Nevin. Undeterred, the Nevins took their case all the way to the U.S. Supreme Court, and the trial finally took place on March 16, 1981. In his opening statement, Edward Nevin III, a lawyer himself, questioned the legal and ethical validity of biological warfare experiments, stating:
«"On what basis does the US government justify releasing a large collection of bacteria into the civilian population in an experiment... without informed consent?"»
Unfortunately for Nevin, the government assembled a formidable team of legal representatives and expert witnesses, including attorney John Kern, who began to refute all of Nevin's arguments. Kern claimed that the bacterial strain that killed Nevin's grandfather was a completely different strain than the one used in the experiments. as part of Operation Sea Spray« . Moreover, in tests conducted at Fort Detrick in 1940, volunteers exposed to Serratia marcescens , suffered from nothing more serious than a cough, red eyes, and fever, with symptoms lasting no more than four days. Kern then dramatically proved his point by raising his pen in the air and declaring:
«"Every atom in this enclosure could, right now, decide to rise about six inches and spin 180 degrees. That would be about as likely as bacteria killing someone.".
One of Kern's witnesses, a doctor in the biological warfare unit at Fort Detrick, agreed, chillingly stating:
«"The strain [was not] pathogenic, [and] I would spray SF again today.".
Kern then began to refute Nevin's arguments regarding the legality of biological weapons testing, making the unusual claim that the government does not need permission to experiment on people without their consent or knowledge. While the Federal Tort Claims Act of 1946 gives the public the right to sue the federal government, that right is suspended in cases where the government «"acts properly in accordance with policy.". According to Kern, this exception extended to activities carried out in the interests of national security, including spraying bacteria on civilians.
Though Nevin fought valiantly, he knew it was all over when Kern called his final witness to the stand: General William Creasy, commander of the U.S. Army's biological warfare division. In his testimony, Creasy argued that obtaining informed public consent was not only unnecessary but also undesirable, stating:
«"I find it completely impossible to conduct such a test while trying to obtain informed consent. I couldn't hope to prevent panic in the uninformed world we live in by telling them we were about to spread non-pathogenic particles throughout their community; 99 percent of people wouldn't know what 'pathogenic' meant.".
From that point on, the court became even more combative: Creasy scolded Nevin for his alleged disrespect for military officials and even attempted to start a fight during recess. Ultimately, however, the Supreme Court sided with the government and refused to overturn the San Francisco Circuit Court's decision. The Nevins' four-year battle for justice ended in defeat.
Meanwhile, concerns have arisen regarding the safety of the zinc cadmium sulfide simulant used in the US Army's LAC experiments. Although the compound was considered harmless at the time, it is now known that cadmium is a potent human carcinogen and, in high concentrations, can cause damage to the lungs, kidneys, and other organs. After learning of the stimulant spraying experiments in St. Louis, sociology professor Lisa Martino-Taylor claimed in 2012 that she reviewed medical records and found a significant spike in cancer cases in the decades following the tests. However, no further evidence has emerged to support this connection, and the official US National Research Council study on the matter concludes:
«"After a comprehensive independent review requested by Congress, we found no evidence that exposure to zinc cadmium sulfide at these levels could cause illness in humans.".
Thus, without further independent research, the true consequences of the LAC experiments will never be known. But regardless of the morally dubious nature of these experiments, they appear to have produced genuinely beneficial results. As Leonard Cole, associate professor of political science at Rutgers University, explains:
«"These tests have taught us a lot about how vulnerable we are to biological attack. I'm sure this is one of the reasons why crop harvesting was banned after 9/11: the military knows how easy it is to spread organisms that can infect humans over vast areas.".
Today, the knowledge gained from these tests is used exclusively for defensive purposes. In 1972, 109 countries, including the United States, signed Convention on the Prohibition of the Development, Production and Stockpiling of Bacteriological (Biological) and Toxin Weapons and on Their Destruction . Since then, the US military has not maintained any offensive or defensive biological warfare capabilities—at least not officially. However, accusations persist that human testing has been carried out secretly. For example, in 2019, New Jersey Republican Representative Chris Smith claimed that the US Army released ticks infected with Lyme disease from 1950 to 1975 to test their effects on American society. If true, this would mean the US government knew about Lyme disease long before its official discovery in 1982. However, no conclusive evidence has yet emerged to support Smith's claims.
Along with other secret military projects of the era, such as the CIA's MKULTRA mind-control experiments and plutonium injection research at the University of California, the US Army's biological warfare tests represent one of the greatest ironies of the Cold War. Although these experiments were ultimately intended to protect society and preserve American institutions, they ultimately succeeded only in harming millions of American citizens, destroying their faith in those institutions, and proving the old adage:
«"Just because you're paranoid doesn't mean you're paranoid.".
This means they are not going to bother you.