These are munition workers who died of TNT poisoning during the manufacture of ammunition for the front lines of World War I.
[2] Shells were filled with a mixture of TNT (the explosive) and cordite (the propellant),[citation needed] and even though these ingredients were known to be hazardous to health, they were mixed by hand so came into direct contact with the workers' skin.
A medical investigation was carried out by the government in 1916, to closely study the effects of TNT on the munitions workers.
The investigators were able to gather their data by acting as female medical officers posted inside the factories.
[3] It is possible that the irritative symptoms were also partly caused by the cordite in the shell mixture, although this was not established until years later.