In the United States, the mercury-based process continued to be adopted until as late as 1941, when it was abandoned mainly due to the wartime need for the heavy metal in the manufacture of detonators.[1][2] Thus, for much of the 20th century mercury poisoning remained common in the U.S. hatmaking industries, including those located in Danbury, Connecticut (giving rise to the expression the "Danbury shakes").[8][4]