These are munition workers who died of TNT poisoning during the manufacture of ammunition for the front lines of World War I. Working with TNT caused many health issues, commonly called TNT poisoning, the most serious of which was a liver disease called toxic jaundice. According to historian Anne Spurgeon, during the First World War, there were 400 cases of the disease of which about 100 were fatal. Munition workers were sometimes called Canary Girls, British women who worked in munitions manufacturing trinitrotoluene (TNT) shells during the First World War1 (1914–1918). The nickname arose because exposure to TNT is toxic, and repeated exposure can turn the skin an orange-yellow colour reminiscent of the plumage of a canary.