Operation LAC

Operation LAC (Large Area Coverage) was a United States Army Chemical Corps operation which dispersed microscopic zinc cadmium sulfide (ZnCdS) particles over much of the United States and Canada in order to test dispersal patterns and the geographic range of chemical or biological weapons.

[3] In St. Louis in the mid 1950s, and again a decade later, the army sprayed zinc cadmium sulfide via motorized blowers atop Pruitt-Igoe, at schools, from the backs of station wagons, and via planes.

Military operators considered the test a partial success because some of the particles were detected 1,200 miles away, at a station in New York state.

[7] According to Leonard A. Cole, an Army Chemical Corps document titled "Summary of Major Events and Problems" described the scope of Operation LAC.

However, a U.S. government study, done by the U.S. National Research Council, stated, in part, "After an exhaustive, independent review requested by Congress, we have found no evidence that exposure to zinc cadmium sulfide at these levels could cause people to become sick.

[11] According to the National Library of Medicine's TOXNET database, the EPA reported that Cadmium-sulfide was classified as a probable human carcinogen.