Dusts in all forms in the studio should be avoided. They accumulate over the years and cause emphysema, not a nice disease to have. Take special care with silica.
Testing for toxicity:
Toxic or hazardous materials can also be ingested by the contamination of food by toxic metals released from fired ware. Pottery for domestic use should be tested for metal release and conform to British Standard: 4800 parts 1&2 (Part 2 is for cooking only). Most pottery suppliers will arrange for this test to be carried out.