File 021 · 1950 · Biological testing

Operation Sea-Spray

In September 1950 the US Navy sprayed bacteria from ships off San Francisco to test how a biological attack would spread. A later Senate hearing revealed that residents were exposed without being told.

Background

At the start of the Cold War the US military worried that the Soviet Union might use biological weapons against American cities. To learn how a germ cloud would spread, the Navy decided to run a test over a real city. In September 1950 ships off the coast of San Francisco sprayed a cloud of bacteria, mainly Serratia marcescens, which was then believed to be harmless, to see how far and how thickly it would travel.

The test was secret. The public was not told until 1976 and 1977, when a Senate hearing on biological testing, partly triggered by a newspaper investigation and the Church Committee, revealed that the Army and Navy had carried out many such trials.

What the record shows

• Military reports describe the 1950 San Francisco test and the idea that the area's fog would help spread the organisms.
• Hospital records show a cluster of unusual Serratia infections at a San Francisco hospital soon after the test. One patient, Edward Nevin, died.
• The 1977 Senate hearings documented a series of open-air bacterial tests on US populations.
• The government was not held liable in the 1981 case; the court ruled on grounds of government immunity, not on whether the test caused the death.

Timeline

• 20–27 Sep 1950 Navy ships spray bacteria into the air off San Francisco over several days.
• Oct–Nov 1950 Several patients at a San Francisco hospital develop rare Serratia infections; one patient dies.
• 1966 The Army releases a harmless bacterium in the New York City subway system to study how it spreads.
• 1976–77 Senate hearings reveal the tests and the 1950 episode.
• 1981 A lawsuit by the family of the man who died is rejected by a federal court on legal grounds.

Checking the claims

The claim: the US government sprayed its own citizens with bacteria. This is documented. The Army and Navy designed the tests to learn how weapons might work and used harmless-seeming stand-ins instead of real pathogens. It was accepted at the time that the stand-in organisms posed no danger, an assumption that later proved wrong for people with weakened immune systems.

What is less clear is the link between the test and every illness claimed. Scientists later argued about whether the 1950 cluster was caused by the Navy's test. It is a documented secret test, but not every outcome attributed to it can be proved.

Claimed, but not shown

Claims that the tests deliberately aimed to harm civilians are not supported. The documented fault was exposing people without their knowledge on an assumption that the organisms were safe.

Verdict

Sources

• US Senate, Biological Testing Involving Human Subjects by the Department of Defense (hearings, 1977)
• US Army report on biological warfare field tests, summarized in the 1977 hearings
• Nevin v. United States, 696 F.2d 1229 (9th Cir. 1983)

Connected files (red threads)

• The Guatemala syphilis experiments — Cold War-era testing on people who did not know
• MKUltra — Another Cold War program that tested on people who did not know
• The Church Committee and the 'Family Jewels' — Revealed in the same 1970s investigations

← Back to the case board