In former times, which workers were prone to a condition known as "phossy jaw"?

This horrible and sometimes fatal condition was technically known as "phosphorus necrosis of the jaw" and afflicted workers in the matchstick industry due to coming into contact with poisonous white/yellow phosphorus. It was first diagnosed in Vienna in 1839, though it existed long before then.

Initially it could have been mistaken for a severe toothache, but soon spread to the jawbone, and could infect the whole body. It also caused the unfortunate victim to emit a terrible smell, and could even cause their bones to glow in the dark. Eventually this could lead to organ failure, and especially when the disease reached its severe stages, the only effective "treatment" was removal of the jaw bone, but this in itself could lead to death by malnutrition. The brain could also be affected.

Thankfully, the banning of the use of phosphorus (Finland leading the way in 1873) has led to this condition being virtually eliminated.