Two Ironworkers were setting a rebar column onto a double rebar mat footing. After the column was guided off Ironworker climbed the column to cut extra rebar off. Injured Ironworker started to finish tying column dowels to rebar mat. Ironworker cut rebar loose and accidentally dropped one and it fell hitting injured in the back causing a 1 1/2"" laceration to the right rear flank.