Zinc cadmium sulfide

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Zinc cadmium sulfide is a mixture of zinc sulfide (ZnS) and cadmium sulfide (CdS). It is used for its fluorescent properties.


Operation LAC (Large Area Coverage) was a United States Army Chemical Corps operation in 1957 and 1958 which dispersed microscopic zinc cadmium sulfide (ZnCdS) particles over much of the United States. The purpose was to determine the dispersion and geographic range of biological or chemical agents. Zinc cadmium sulfide was used as it could be easily detected. It was not thought at the time to pose any particular health risk.

It was also used in an experiment on unwilling civilians in the UK and Canada.[1]

Health effects[edit]

Anecdotal evidence[2] exists of ZnCdS having adverse health effects as a result of LAC. However, a 1997 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."[3] It said that the material was dispersed at very low levels, and people were exposed to higher levels in typical urban environments. Responding to the 1997 study, Leonard A. Cole said that by testing ZnCdS the Army was "literally using the country as an experimental laboratory".[4]

See also[edit]


  1. ^ Portion Down – The Unwitting Victims, BBC, October 28, 2002
  2. ^ LeBaron, Wayne. America's Nuclear Legacy, (Google Books), Nova Publishers, 1998, p. 83–84, (ISBN 1560725567).
  3. ^ Leary, Warren E. "Secret Army Chemical Tests Did Not Harm Health, Report Says", The New York Times, May 15, 1997, accessed November 13, 2008.
  4. ^ Moreno, Jonathan D. (2001). Undue risk : secret state experiments on humans (Routledge ed.). New York [u.a.]: Routledge. p. 235. ISBN 0415928354. Retrieved 11 May 2018.

External links[edit]