The History of Chemicals Against Nature

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Between 1962 and 1971
  –  

Vietnam War - Agent Blue

65.6% organic arsenicical (cacodylic acid (Ansar 138) and its sodium salt sodium cacodylate)[2]

Tonnage used: The only agent used on a large scale in an anti-crop role was Agent Blue, with 142,166,656 U.S. gal (538,159,330 L; 118,378,504 imp gal) used.[10]