There are far worse conditions that arise from welding (and more so from welding incorrectly) that Parkinson's is the least of your worry. Even then, "so what" comes to mind. If you love doing it the fear of death shouldn't stop you. A youtuber I love once said "Has anyone ever noticed how there aren't any old welders? (cynical chuckle)". He's right but people still do it.

You can also, in some cases, avoid using manganese based fluxes. There are quite common rods without the presense of manganese.