Hazards

Hazards in the making and use of traditional ceramics.

Introduction

A wide range of materials are used in ceramics. Many of them are harmless, they can be breathed or eaten with little effect. Hundreds of tons of clays are sold each year for the specific purpose of eating them! And many more for cosmetic and medicinal uses. Most ceramic materials are inert, insoluble and among the most stable of materials. That means that it is not dangerous to, once in a while, touch or handle the vast majority of materials. However, if there is constant exposure, then long-term effects need to be considered. Notwithstanding this, some materials do have specific acute or short-term exposure hazards (by ingestion or inhalation).

Material hazards are most commonly related to dust. But there is a need to be sensible about it. One cigarette, for example, does not kill. Nor do 100. But 100,000 can. Likewise, there may be some asbestos fibres in talc or vermiculite, but you will not be harmed by sweeping up a little of either. You will be harmed if exposed to the dust daily for years and take no precautions. Consider frits to illustrate the need for common sense: Hundreds are available. They are ground glass powders, which means each particle is a glass shard, potentially with razor-sharp angular edges! It is not easy to find hazard information on frits (likely because there are so many types and each pulverizes to a different particle shape). Yet simple logic tells us to be careful about breathing the dust. And, to illustrate the need for perspective, consider silicosis: It is a much more serious health issue than asbestosis. Yet pretty well all dust in nature contains some quartz. Even gardening, farming or just walking in dry areas exposes one to quartz dust. This is because quartz makes up 20% of the earths crust. So minimizing exposure over the years is the common sense approach.

Some materials produce harmful fumes at certain temperatures during firing. Bodies or glazes with high percentages of manganese dioxide (and other metal oxide raw materials), for example, can fume and should be considered hazardous. Fumes don't settle the same as dust, they can stay in the air for long periods. The obvious precaution is to install a vent on your kiln.

Some materials are poisonous or toxic if eaten. Barium carbonate or lithium carbonate are examples. But this is not common.

There is a special need for caution about material hazards when production is being ramped up from a hobby level to a business. The economic and scheduling pressures often mean that precautions and facility hygiene are put aside temporarily (and never restored). It is thus important that safety and common sense be an integral part of any business plan to produce ceramics.

Links

Articles	Crazing and Bacteria: Is There a Hazard? A post to a discussion on the clayart group by Gavin Stairs regarding the food safety of crazed ware.
Articles	Is Your Fired Ware Safe? Glazed ware can be a safety hazard to end users because it may leach metals into food and drink, it could harbor bacteria and it could flake of in knife-edged pieces.
Articles	Attack on Glass: Corrosion Attack Mechanisms Max Richens outlines the various mechanisms by which acids and bases can dissolve glass and glazes. He provides some information on stabilizing glazes against attack.
URLs	http://www.ilo.org/public/english/protection/safework/cis/products/icsc/dtasht/index.htm International Labour Organization Chemical Safety Database
URLs	http://www.atsdr.cdc.gov/toxprofiles/index.asp CDC Toxicity Profiles of many substances
URLs	https://www.iloencyclopaedia.org The Encyclopedia of Occupational Health & Safety
URLs	http://www.ccohs.ca/oshanswers/chemicals/whmis_ghs/sds.html Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
URLs	https://www.ccohs.ca/oshanswers/chemicals/whmis_ghs/sds.html WHMIS Safety Data Sheet Overview
URLs	https://www.osha.gov/annotated-pels/note Permissible Exposure Limits to Substances – Annotated Tables from OSHA
URLs	https://www.wiley.com/en-ca/Patty%27s+Industrial+Hygiene,+4+Volume+Set,+7th+Edition-p-9781119438021 Patty's Industrial Hygiene, 4 Volume Set, 7th Edition
URLs	https://pubchem.ncbi.nlm.nih.gov/ PubChem, the world's largest collection of freely accessible chemical information
URLs	https://www.lung.org/lung-health-diseases/lung-disease-lookup/occupational-lung-diseases Occupational Lung Diseases
URLs	https://monographs.iarc.who.int World Health Organization information of carcinogenic hazards
URLs	https://www.elsevier.com/books/sittigs-handbook-of-toxic-and-hazardous-chemicals-and-carcinogens/pohanish/978-1-4377-7869-4 Sittig's Handbook of Toxic and Hazardous Chemicals and Carcinogens
Glossary	Leaching Ceramic glazes can leach heavy metals into food and drink. This subject is not complex, there are many things anyone can do to deal with this issue

Flow diagram of a pottery operation

Each stage presents potential health hazards. Photo courtesy of American Conference of Governmental Industrial Hygienists.

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