CO2 is CO2. The problem is not with the gas, but the handling of it and the containers it is dispensed from and stored in. There is always a possibility that impurities may be introduced into the cylinder while being filled. While food service providers may be more careful, there's still a chance of contaminants, though it is likely smaller than a welding supply.
As Robert said, check with local bars and restaurants to see where they get theirs. Better yet, ask a local brewery.