EE WAS CLIMBING ONT OF THE BED OF APICK UP TRUCK. HE SLIPPED AND FELL BACKWARDS ONTO THE CONCRETE FLOOR OF THE DIESEL SHOP AT THE PREPANTION PLANT. FELT PAIN IN LOWER LEFT BACK AND LEFT RIBS O IL ACCUMULATION IN BED OF TRUCK CAUSED EE TO SLIP. THERE WAS NO DAMAGE OR IMPAIRMENT TO THE MINING OPERATION OR EQUIPMENT. THE INJURY DID NOT INVOLVED COMPLIANCE JOB SKILLS, PROF. ATTITUDE.