How are workers exposed to cadmium or cobalt in hard metal?
A number of inspections in the state have revealed worker overexposures to cadmium from brazing with cadmium-containing solder, from grinding or sand- blasting hard metal tools made with cadmium-containing solder, and even from grinding operations in which “cadmium free” solders were used to attach the hard metals. Workers also can be exposed to cadmium by ingestion and through contact with cadmium in dust on hands and work surfaces. Cobalt, which is a routine ingredient of tungsten carbide and other hard metals, may be released into air during the manufacture, finishing, grinding, filing, sharpening, brazing, welding, or sandblasting of hard metal. Exposure could be in the form of cobalt metal fumes created when hard metal is brazed or welded to other metals, or as airborne cobalt metal produced by dry or wet grinding operations. Grinding coolants commonly leach cobalt from ground hard metal, and the concentration of cobalt dissolved in coolant can increase over time. Even when hard m
