Beech 1900
Flight Crew Air Transport Pilot (ATP)
Training / Qualification
Deviation / Discrepancy - Procedural Hazardous Material Violation; Deviation / Discrepancy - Procedural Published Material / Policy
Human Factors
While unloading the plane; some boxes were found that had the diamond-shaped 'BIOHAZARD' placard.  They were not otherwise labeled and no shipper's declaration paperwork was given to me. [The company] says it does need paperwork since it had the diamond-shaped placard so we left the boxes behind. There seems to be a lot of debate about the nature of biohazard.  Better education about the specifics of what biohazard needs paperwork and what doesn't would help prevent this from happening.
While unloading the plane some boxes were found that had a diamond shaped 'biohazard' placard. They were not otherwise labeled and no shipper's declaration paperwork was given to the Captain. The Captain called [the company] who said the shipment originated from [a specific station]. That station told them that biohazard does not need paperwork; but [the company] says it does need paperwork since it had the diamond shaped placard. We left the boxes behind.
Flight crew reports discovering a biohazard shipment onboard at an intermediate stop which has no paperwork. The shipment is left behind.