Overview

On March 13, 1968, a malfunction on a jet's disposal tank from the Dugway Proving Ground in Northwest Utah spewed roughly 20 pounds of a VX solution at such an altitude that it was dispersed by the wind to neighboring communities. The solution killed more than 6,000 sheep throughout the region.

The U.S. General Accounting Office issued a report on September 28, 1994, which stated that between 1940 and 1974, DOD and other national security agencies studied "hundreds, perhaps thousands" of weapons tests and experiments involving hazardous substances.

The quote from the study:

" ... Dugway Proving Ground is a military testing facility located approximately 80 miles southwest of Salt Lake City. For several decades, Dugway has been the site of testing for various chemical and biological agents. From 1951 through 1969, hundreds, perhaps thousands of open-air tests using bacteria and viruses that cause disease in human, animals, and plants were conducted at Dugway... It is unknown how many people in the surrounding vicinity were also exposed to potentially harmful agents used in open-air tests at Dugway

References

Dugway Proving Ground - wikipedia