EE WAS SECURING A PRODUCT LOAD IN AN UNEQUIPPED RAILCAR USING OLD PALLETS AND STRAPPING. HE STOOD THE FIRST PALLET ON END AGAINST THE LOAD, TURNED TO REACH AND PLACE A SECOND PALLET WHEN THE F IRST ONE TIPPED OVER, STRIKING HIM THE LOWER MIDDLE PART OF HIS BACK. EE DECLINE INTIAL MEDICAL TREATMENT; SOUGHT TREATMENT THE FOLLOWING DAY ON 1-16-03.