See page 57 of Ancient Egyptian Medicine by John Nunn (See
http://books.google.com/books?id=WHfEnVU6z8IC&pg=PT1&dq=scholar:+Ancient+Egyptian+Medicine+Nunn#PPA57,M1 ). On this page, there is a drawing of a relief in the Deir el Medina tomb of a Dynasty XX (11th or 12th century BCE) man (necropolis worker) named Ipwy. The scene shows a group of workers building a catafalque (a platform to support a coffin) and the variety of occupational injuries (foot hurt by a dropped mallet, foreign body in eye, dislocated shoulder from fall) that can occur (as well as their treatments).
As far as I know, this is the first recorded reference to occupational injuries.