Amorphous or noncrystalline silica includes such materials as diatomaceous earth and cabosil. Silicosis takes at least 10 years to develop and entails symptoms such as shortness of breath, dry cough, emphysema, and high susceptibility to lung infections such as tuberculosis. Skin contact and ingestion pose no significant hazards. Inhalation of large quantities of China clay powder is moderately hazardous, causing kaolinosis, a disease in which the lungs becomes mechanically clogged by the clay. China clay may also cause silicosis if it contains free silica.
Asbestos is highly toxic by inhalation and possibly by ingestion.
It may cause asbestosis, lung cancer, mesothelioma, stomach cancer and intestinal cancer. Talcs are often contaminated with asbestos. Respiratory problems can also result from inhalation of powders that develop when aged clay dries. The molds, which can contribute to the workability of the clay, can cause skin problems, particularly if there is a pre-existing dermatitis. Handling cold wet clay, such as when throwing clay, can cause abrasion and drying of the hands, particularly the fingertips.