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Ceramic Toxic Materials

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Due to the need for a comprehensive listing of toxic ceramic materials on the Net, I have put together information on this subject. Below you will find a listing of 35 common and not so common ceramic ingredients -- the stuff that we deal with on a daily basis. While most of this knowledge is freely available, my experience at various art schools has told me that the toxicity of ceramic materials is not stressed enough. Even well known figures in the ceramic world have been known to disregard common sense rules. One well-known tragic incident was Hans Copers death from manganese poisoning. The instances of emphesemia due to dust inhalation amongst potters is too high -- a sickness which is fairly easily avoided. I hope this list will contribute to the knowledge available on ceramic toxins on the Net.

Many substances are a problem for the potter during production, e.g. through touch or inhalation, others in the finished product. A designates a substance which may be hazardous to health, either through inhalation or assimilation through the skin. Some substances should not be used for tableware, usually due to leaching. While the substaces listed may be hazardous, this does not mean they cannot be used at all - rather that caution should be used! Note that some ingredients listed may not be designated as toxic, but may be hazardous nonetheless. To make a contribution to this database, please send an email .
A comprehensive list of MSDS (Material Safety Data Sheets) is available here: http://avogadro.chem.iastate.edu/MSDS/.
Safety Measures: 
  • know the materials you are dealing with
  • wear a good dust mask when handling dry materials
  • wear gloves when touching any raw materilas, dry or wet
  • avoid using particularly toxic raw materials, such as white lead. Use frits instead.
  • wash hands carefully after contact with materials
  • wear protective clothing and wash frequently
  • wear a gas mask when reducing or salt or soda firing 
  • wash workbenches and wet mop studio floors
  • if spraying glazes, wear a mask and use a spray booth
  • never eat or drink near studio or working area

Ceramic Toxic Materials List

Alumina dust is a nuisance to lungs
Asbestos causes particularly nasty, incurable fibrosis if inhaled. More info.
Barium Carbonate
is a dangerous form of barium, as it forms a soluble chloride in the stomach and accumulates. It affects muscles, in particular the heart, increasing its excitability, leading to high blood pressure and internal bleeding. Will penetrate the skin. Not recommended for food ware, as it may leach.
See Feature Article for more info.
Borax chronic exposure can cause asthma, diarrhoea and skin conditions 
 Used as a pigment in glazes. Can cause respiratory diseases, osteoporosis, cancer and other problems. See Feature Article for more information.
Carbon Dioxide 
If the oxygen level falls, hearing will decrease, pulse and blood pressure rise. Carbon dioxide forms during combustion firing processes. 
Carbon Monoxide 
combines in the body with the haemoglobin in the blood and reduces the availability of oxygen to the body. Symptoms such as headache, dizziness and fatigue appear in healthy people when 10% of their haemoglobin combines with carbon monoxide. Can lead very quickly to drowsiness, then death. Forms during heavy reduction firings. More info.
Chromates and Chromic Acid 
may be cancerous. Will also enter the body through the skin. 
See Feature Article for mor information.
Cobalt Oxide, Carbonate 
can cause liver damage and dermatitis. Will enter the body through the skin. 
salts are irritants to the skin, eyes,and mucous membranes. Inhalation of copper dust and fume results in irritation of the respiratory tract. See Feature Article for more information. 
Dusts in all forms in the studio should be avoided. They accumulate over the years and cause emphesemia -- not a nice disease to have. Take special care with silica.
Ferrous Sulphite
can be fatal and should be avoided.
Fiber Blanket especially in the fired state can shed invisible floating fibres that have similar effects to asbestos.
Gases from salt kilns and reducing kilns, can cause respiration trouble or even acid corrosion of lung tissue. 
Gum Arabic may cause asthma and eye inflammations.
Iron Chromate
may lead to acute pneumonia and cause lung cancer. 
Iron Oxide Dust is poisonous for children and can cause "iron pigmentation" of the lungs, supposedly benign but contentious.
Kaolin similar to silica
is an accumulative poison. It can be stored in the bone structure for years before a fatal dose is accumulated. Beware of raw lead froms, such as white or yello lead, which are extremely toxic. Use lead frits instead. Do not use for tableware.
Liquid Petroleum Gas can cause headaches, numbness, chills and vomiting, but is a greater risk as explosive than inhalation.
Magnesium Oxide is considered inoxious, but general rules for dusts still apply.
Manganese can lead to brain damage and eventually death. Will penetrate skin.
See Feature Article for mor information.
Mica, Muscovite, Vermiculite, Lipidolite may contain traces of asbestos. Inhalation of dust will lead to lung irritation and coughing, possibly cancer, pneumoconiosis, dyspnea.
Nickel Oxide can cause cancer. Will cause skin irritation ('nickel itch'). Will penetrate skin.
Platinum may cause asthma.
Potassium Dichromate/ Bichromate
is very poisonous. Can cause kidney failure and is cancerous. Avoid all contact! Not recommended for tableware!
Selenium affects the liver.
Silica is everpresent in clay materials. Repeated inhalation will cause potentially fatal silicosis, or 'potters' asthma', a form of emphesemia. The molecule (especially when fired) has a 'hook' which attaches itself to the lung wall and accumulates and irritates.
Sulpher Dioxide is a strong lung irritant and can form when firing soluble metal salts.
Talc similar to silica
Tin Oxide can result in 'stannosis', supposedly a benign condition. More info.
Titanium Dioxide causes pulmonary irritation in chronically exposed workers. More info.
Uranium Compounds cause kidney damage, not to mention the radioactivity.
Vanadium Pentoxide can cause Anemia; it a respiratory irritant. See Feature Article for more info. More info also here.
Zinc Oxide primarily a nuisance dust, but exposures to high concentrations can result in respiratory system effects. More info.
Zirconium contact of the skin with zirconium or zirconium compounds has caused skin granulomas in the form of linear streaks of small papules; also causes pulmonary granulomas after prolonged exposure. More info.

Disclaimer: this database is by no means a complete listing of toxic materials. It is a guide only. It remains the duty of each individual handling these and other substances to insure that the proper safety standards are met, and that he/she is fully informed on the levels of toxicity of the various substances he/she is using. For more information, refer to the relevant literature available.

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