EE WAS BAGGING CEMENT WHEN A BAG BROKE. INSTEAD OF LETTING THE BAG FALL TO THE CONVEYOR BELOW, HE REACHED DOWN AND TRIED TO TEAR THE BAG OPEN TO EMPTY THE CEMENT INTO THE HOPPER BELOW THE CONV EYOR. WHEN HE PULLED ON THE HEAVY BAG OF MATERIAL, HE PULLED THE MUSCLES IN HIS LOWER BACK.