Operation LAC (Large Area Coverage), was a U.S. Army Chemical Corps operation which dispersed microscopic zinc cadmium sulfide

Zinc cadmium sulfide

Zinc cadmium sulfide is a mixture of zinc sulfide and cadmium sulfide . It is used for its fluorescent properties.-Use:Operation LAC , was a Chemical Corps operation in 1957 and 1958 which dispersed microscopic zinc cadmium sulfide particles over much of the United States...

 (ZnCdS) particles over much of the United States. The purpose was to determine the dispersion and geographic range of biological or chemical agents.

Earlier tests

There were tests that occurred prior to the first spraying affiliated with Operation LAC. The Army admitted to spraying in Minnesota locations from 1953 into the mid-1960s.

Operation

Operation LAC was undertaken in 1957 and 1958 by the U.S. Army Chemical Corps. Principally, the operation involved spraying large areas with zinc cadmium sulfide. The U.S. Air Force loaned the Army a C-119, "Flying Boxcar", and it was used to disperse zinc cadmium sulfide by the ton in the atmosphere over the United States. The first test occurred on December 2, 1957 along a path from South Dakota to International Falls, Minnesota

International Falls, Minnesota

International Falls is a city in and the county seat of Koochiching County, Minnesota, United States. The population was 6,424 at the 2010 census....

.

The tests were designed to determine the dispersion and geographic range of biological or chemical agents. Stations on the ground tracked the fluorescent zinc cadmium sulfide particles. During the first test and subsequently, much of the material dispersed ended up being carried by winds into Canada. However, as was the case in the first test, particles were detected up to 1,200 miles away from their drop point. A typical flight line covering 400 miles would release 5,000 pounds of zinc cadmium sulfide and in fiscal year 1958 around 100 hours were spent in flight for LAC. That flight time included four runs of various lengths, one of which was 1,400 miles.

Specific tests

The December 2, 1957 test was incomplete due to a mass of cold air coming down from Canada. It carried the particles from their drop point and then took a turn northeast, taking most of the particles into Canada with it. 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. A February 1958 test at Dugway Proving Ground ended similarly. Another Canadian air mass swept through and carried the particles into the Gulf of Mexico. Two other tests, one along a path from Toledo, Ohio

Toledo, Ohio

Toledo is the fourth most populous city in the U.S. state of Ohio and is the county seat of Lucas County. Toledo is in northwest Ohio, on the western end of Lake Erie, and borders the State of Michigan...

 to Abilene, Texas

Abilene, Texas

Abilene is a city in Taylor and Jones counties in west central Texas. The population was 117,063 at the 2010 census. It is the principal city of the Abilene Metropolitan Statistical Area, which had a 2006 estimated population of 158,063. It is the county seat of Taylor County...

, and another from Detroit, to Springfield, Illinois

Springfield, Illinois

Springfield is the third and current capital of the US state of Illinois and the county seat of Sangamon County with a population of 117,400 , making it the sixth most populated city in the state and the second most populated Illinois city outside of the Chicago Metropolitan Area...

, to Goodland, Kansas

Goodland, Kansas

Goodland is a city in and the county seat of Sherman County, Kansas, United States. As of the 2010 census, the city population was 4,489.-History:...

, showed that agents dispersed through this aerial method could achieve widespread coverage when particles were detected on both sides of the flight paths.

Scope

According to Leonard A. Cole

Leonard A. Cole

Leonard Cole, an expert on bioterrorism and terror medicine, is an adjunct professor of political science at Rutgers University-Newark, New Jersey, where he teaches on terrorism issues in the Division of Global Affairs...

, an Army Chemical Corps document titled "Summary of Major Events and Problems" (1958) described the scope of Operation LAC. Cole stated that the document outlined that the tests were the largest ever undertaken by the Chemical Corps and that the test area stretched from the Rocky Mountains to the Atlantic Ocean, and from Canada to the Gulf of Mexico. Other sources describe the scope of LAC varyingly, examples include, "Midwestern United States", and "the states east of the Rockies". Specific locations are mentioned as well. Some of those include: a path from South Dakota to Minneapolis, Minnesota,Dugway Proving Ground

Dugway Proving Ground

Dugway Proving Ground is a US Army facility located approximately 85 miles southwest of Salt Lake City, Utah in southern Tooele County and just north of Juab County...

, Corpus Christi, Texas

Corpus Christi, Texas

Corpus Christi is a coastal city in the South Texas region of the U.S. state of Texas. The county seat of Nueces County, it also extends into Aransas, Kleberg, and San Patricio counties. The MSA population in 2008 was 416,376. The population was 305,215 at the 2010 census making it the...

, north-central Texas, and the San Francisco Bay area

San Francisco Bay Area

The San Francisco Bay Area, commonly known as the Bay Area, is a populated region that surrounds the San Francisco and San Pablo estuaries in Northern California. The region encompasses metropolitan areas of San Francisco, Oakland, and San Jose, along with smaller urban and rural areas...

.

Risks and issues

A large body of evidence exists of ZnCdS having adverse health effects as a result of 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." Still, the use of ZnCdS remains controversial and some critics have accused the Army of "literally using the country as an experimental laboratory".

Further reading

• Subcommittee on Zinc Cadmium Sulfide, U.S. National Research Council, Toxicologic Assessment of the Army's Zinc Cadmium Sulfide Dispersion, (Google Books), National Academies Press, 1997, (ISBN 0309057833).