What materials are toxic?
The two materials that are proven toxic at this time are lead and cadmium. Lead is used to make glazes flow better at low temperatures. Cadmium is used primarily to create bright orange and red colors. There are other materials which may be toxic, but there is not enough evidence that they are unsafe at this time, so they are not regulated. Many of these materials are safe in low doses (for example, nickel, barium, selenium and cobalt), but toxic in high doses. So reducing leaching as much as possible is always a good idea. Toxicity in pre-fired form (liquid or dry) Commercial glaze manufacturers label their glazes using ASTM D-4236. All their glazes are either AP Non-toxic, which means non-toxic in liquid or dry form, or CL Cautions Required, which means it has proper labeling of ingredients for health and safety. In this sense, non-toxic only refers to lead and cadmium. All glazes sold in K-12 schools must be AP Non-toxic. This is to reduce the risk of harm if a child drinks the glaz
