There are several brands of 15% silver solder (braze) that are cadmium free. Most use phosphorus as an alloying agent instead of cadmium. Additionally when brazing copper to copper with these silver bearing rods, all manufacturers state that they are self fluxing, so no flux is required. This all but eliminates the risk of cadmium toxicity.
All soldering, brazing, and welding should be done in a well t ventilated area, and all fumes should be avoided.