The process in progress at the time of the event was the manufacture of methatrexate, an anti-cancer drug. Shortly after employee #1 began to draw bromine liquid into the supposedly clean and empty charging pot, he heard a hissing sound. He then saw a purple haze spewing out from under the lid of the pot.
Analysis of the residue left behind inside the charging pot showed that bromine had reacted vigorously and exothermically with acetone to form bromo acetone and hydrogen bromide. Bromo acetone is a purple substance which is extremely irritating to the eyes and highly irritating to all mucous membranes and the skin.
Sixteen employees were taken to the hospital, treated for eye irritation and released.
The cause of the event was the failure to remove acetone, which had been used for cleaning, from the charging pot.
