Asbestos in Clay
Clays are made up of a number of different minerals that become moldable and plastic-like when wet. When clays are subjected to heat through the process of firing in a high-temperature oven or kiln, the water is driven out of the clay and the material becomes irreversibly hard and cured, like stone.
Clays are supplied in both wet and dry forms, and other materials are often added to dry clay in order to change the composition of the final material. Dry clay is composed of aluminum silicates which are mixed with water in a clay mixer machine.
Presence of Asbestos in Clay
Since clay is often subjected to high temperatures, the mineral asbestos was often added to certain dry clays in order to lower the temperature at which clay needed to be heated.
As long ago as 2500 B.C., the combination of asbestos and clay was used in Finland to give clay pots added strength upon firing.
In the 20th century in America, asbestos often found its way into dry clay mixes and modeling clay mixes accidentally. Talc, vermiculite and other clay additives were often discovered to be contaminated with asbestos fibers, which, in turn, contaminated the clay with the potentially-dangerous fibers.
Asbestos-containing clay had many uses, including:
- Modeling clays
- Pipe joint seals
- Pipe insulation
- Pottery and ceramics
- Instant papier-mâché mixes (manufactured prior to the mid-1970s)
- Firebricks
Asbestos in Children's Modeling Clay
Modeling clay compounds used by children have often been found to contain high amounts of asbestos fibers. In 1982, New Jersey school authorities determined that asbestos was present in certain packages of "Fibro-Clay," a modeling compound used to make papier-mâché artwork in schools. The product was supplied in powder form, which allowed the dry asbestos particles to be inhaled or ingested easily when the product was mixed with water during use. Ironically, the Fibro-Clay product had been initially labeled as "non-toxic."
Authorities determined that the Fibro-Clay modeling compound could contain as much as 50 percent chrysotile asbestos, a dangerous type of asbestos fiber that likely originated from contaminated talc powder in the clay manufacturing process. A recall was soon issued by the manufacturer of Fibro-Clay, Milton Bradley, as well as the U.S. Consumer Product Safety Commission. Milton Bradley stated that asbestos was used in the compound from 1967 until 1972. After the recall, many health departments urged school districts and consumers to only use talc-free clay and avoid clays supplied in powder form.
Hazards of Asbestos in Clay
Asbestos is particularly dangerous if found in clay, as the mixing process of dry clay can easily result in airborne asbestos particles. Dry clay is often ground to a powder before mixing, and asbestos fibers can easily escape from the mixture and be released into the air, where they can be inhaled and become lodged in the lungs.
Asbestos-clay dust can be extremely toxic if inhaled or ingested, as the fibers can lead to lung scarring, asbestosis, lung cancer, mesothelioma and other cancers. Dried clay that is chipped or sanded can also produce clay dust that releases asbestos into the air.
Individuals at risk for exposure to clay containing asbestos include:
- Clay mixers
- Art teachers
- Pottery studio owners or workers
- Artists
- Custodians and others involved in cleaning up or sweeping up clay dust
Clay that contains asbestos is particularly dangerous if handled during the clay mixing process, as the process generates a large quantity of dust. When dry clay is poured into a clay mixer, tiny particles of silica, talc, asbestos and other particles are released into the air, where they can then be inhaled.
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© 2012 The Mesothelioma Center |
Last Modified Thursday, February 9th, 2012 | Disclaimer | Privacy Policy |
The information provided by The Mesothelioma Center is not a substitute for professional medical advice, diagnosis or treatment.
Sponsored by a law firm concentrating in asbestos litigation, The Peterson Firm, LLP with offices at 1350 Connecticut Ave, NW, Fifth Floor, Washington DC 20036.
