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Operation Sea-Spray was a U.S. Navy secret experiment in which Serratia marcescens and Bacillus globigii bacteria were sprayed over the San Francisco Bay Area in California.

Military test

From September 20 to 27, 1950, the U.S. Navy released the pathogens off the shore of San Francisco. Based on results from monitoring equipment at 43 locations around the city, the Army determined that San Francisco had received enough of a dose for nearly all of the city's 800,000 residents to inhale at least 5,000 of the particles.[1][2][3]


On October 11, 1950, eleven residents checked into Stanford Hospital for very rare, serious urinary tract infections. Although ten residents recovered, one patient, Edward J. Nevin died three weeks later. Cases of pneumonia in San Francisco also increased after Serratia marcescens was released.[4][5] (That the simulant bacteria caused these infections and death has never been conclusively established. Nevin's son and grandson lost a lawsuit they brought against the government between 1981 and 1983.[6]) The bacterium was also combined with phenol and an anthrax simulant and sprayed across south Dorset by US and UK military scientists as part of the DICE trials which ran from 1971 to 1975.[1][7]

The urinary tract outbreak was so unusual that the Stanford doctors wrote it up for a medical journal.[citation needed]

There was no evidence that the Army had alerted health authorities before it blanketed the region with bacteria. Doctors later wondered whether the experiment might be responsible for heart valve infections around the same time as well as serious infections seen among intravenous drug users in the 1960s and 1970s.[8]

Senate subcommittee hearings

In 1977 Senate subcommittee hearings the army disclosed the tests. Army officials noted the pneumonia outbreak in their 1977 Senate testimony but said any link to their experiments was totally coincidental. The army pointed out that no other hospitals reported similar outbreaks and all 11 victims had urinary-tract infections following medical procedures, suggesting that the source of their infections lay inside the hospital.[1]


In 1981 Nevin's surviving family members filed suit against the federal government, alleging negligence. "My grandfather wouldn't have died except for that, and it left my grandmother to go broke trying to pay his medical bills," says Mr. Nevin's grandson, Edward J. Nevin III, a San Francisco attorney who filed the case in U.S. District Court.

The lower court ruled that the government was immune from lawsuits. The Nevin family appealed the suit all the way to the U.S. Supreme Court, which declined to overturn lower court judgments.[1][9][10]

Similar tests

In Senate subcommittee hearings in 1977 the army revealed:

  • Between 1949 and 1969 open-air tests of biological agents were conducted 239 times. In 80 of those experiments, the Army said it used live bacteria that its researchers at the time thought were harmless. In the others, it used inert chemicals to simulate bacteria.
  • In the 1950s army researchers dispersed Serratia on Panama City and Key West Florida with no known illnesses resulting.
  • In the 1950s army researchers dispersed zinc cadmium sulfide (now a known cancer-causing agent) over Minnesota and other Midwestern states to see how far they would spread in the atmosphere. The particles were detected more than 1,000 miles away in New York state. No illnesses were ever attributed to them as a result.
  • Bacillus globigii, never shown to be harmful to people, was released in San Francisco, New York, Washington, D.C., and along the Pennsylvania Turnpike, among other places.
  • In New York, military researchers in 1966 spread Bacillus subtilis variant Niger, also believed to be harmless, in the subway system by dropping lightbulbs filled with the bacteria onto tracks in stations in midtown Manhattan. The bacteria were carried for miles throughout the subway system. Army officials concluded in a January 1968 report that: "Similar covert attacks with a pathogenic [disease-causing] agent during peak traffic periods could be expected to expose large numbers of people to infection and subsequent illness or death."
  • In a May 1965 secret release of Bacillus globigii at Washington's National Airport and its Greyhound bus terminal more than 130 passengers were exposed to the bacteria traveling to 39 cities in seven states in the two weeks following the mock attack.[1]


  1. 1.0 1.1 1.2 1.3 1.4 Jim Carlton,Of Microbes and Mock Attacks: Years Ago, The Military Sprayed Germs on U.S. Cities, The Wall Street Journal, (October 22, 2001).
  2. Leonard A. Cole, Clouds of Secrecy: The Army's Germ Warfare Tests Over Populated Areas - Special Report No. 142: "Biological Warfare Trials at San Francisco, California, 20–27 September 1950".
  3. How the U.S. Government Tested Biological Warfare on America, Priceonomics (October 30, 2014).
  4. Cole, Leonard A. (1988). Clouds of Secrecy: The Army's Germ-Warfare Tests Over Populated Areas. (Foreword by Alan Cranston.). Totowa, New Jersey: Rowman & Littlefield.. ISBN 0-8476-7579-3. 
  5. Regis, Ed. The Biology of Doom : America's Secret Germ Warfare Project.. Diane Publishing Company.. ISBN 0-7567-5686-3. 
  6. Cole, Op. cit., pp. 85-104.
  7. Barnett, Antony (2002-04-21). "Millions were in germ war tests". Retrieved 27 October 2012. 
  8. Bernadette Tansey, Serratia has dark history in region / Army test in 1950 may have changed microbial ecology, San Francisco Chronicle, (October 31, 2004).
  9. Secret Testing in the United States, The American Experience "In the event, the courts ruled against them, the main reason being that the plaintiffs could not prove that the bacteria used in the test were the same as those that killed Mr. Nevin."
  10. Judge's Decision Expected Soon in California Germ Warfre (sic) Case, New York Times, (April 15, 1981)

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