Air Carrier First Officer reported a communications breakdown between ground personnel handling Dangerous Goods. Documentation transmitted to flight crew contained incorrect information. Flight crew refused cargo.

Narrative

During our preflight while finishing up our processes in the cockpit I was handed the Dangerous Goods (DG) paperwork which I did not initially review because we were finishing up the Take-off & Landing Data brief. Once we completed the Take-off & Landing Data brief I reviewed the paperwork. There was no Accessible Dangerous Goods and was not a DG Agent waiting for me so I had not made it a priority to review. Upon review; I immediately noticed that the paperwork indicated a small amount of radioactive material in position 1D. Per FOM; the A300 cannot have radioactive material < 50 TI's [Transportation Index] forward of position 3. I made the Captain aware of the issue and left the flight deck while he called Dispatch and the Duty Pilot. I found the ramp agent and made him aware of the issue. He immediately agreed that he believed the radioactive material was in the can in position 1D and asked another ramp individual if the load team had left because he would have to open the can to find and remove the material. The load team had left and the ramp agent decided to open the XX net and smoke barrier on the right side of the aircraft to begin to access and attempt to unload the can. I let [the] Captain know what was going on and he had just gotten off the phone with the Duty Pilot or Dispatch. A few minutes later we received an ACARS message from Dispatch that stated; 'I was told there is not any [Dangerous Goods] in can 1D. It is a paperwork error and they are fixing it now'. I left the cockpit to tell the ramp agent that we were just notified that it was a paperwork error; his response was to point to a small box on the stairs to the airplane and said that he found it and it had been removed. He told me that he was repacking the can and we would get a new weight-and-balance and DG paperwork in a few minutes. We received the new paperwork and departed shortly after. My main concern lies in the ACARS message that we received telling us that it was a paperwork error but there was actually DG material in the can; indicating that someone lost track of where the potentially hazardous material was located. I believe the cause of this event is a possible training issue with the DG personnel at the [company] hub. The ramp was aware of the radioactive material because it was on the paperwork. It was missed that it should not be loaded in a forward position. [Reporter suggests more] Training and proper communications.