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Asbestos in Magnesia and Other Materials

Magnesia, scientifically known as magnesium oxide, is also known as "magnesia alba" (due to its white coloring) and as periclase. Most magnesium oxide (nearly 60%) is used in refractory applications because of its ability to remain stable at high temperatures. This material is therefore likely to be found in aluminum processing plants as well as smelting operations and anywhere else that flame and heat are a hazard. Magnesium oxide is also one of the basic ingredients in portland cement.

Magnesium oxide has also been used in recent years as a substitute for asbestos in many fireproofing products. As stated above, magnesia remains stable at very high temperatures making it ideal for use in refractory products. Materials such as brick and concrete used in refractory applications in aluminum plants often contained magnesia. Magnesia may also be found in electric, steam-fitting and HVAC insulation materials as well as the linings of kilns, blast furnaces and even nuclear reactors. This type of magnesia is known as dead-burned, and should not be confused with the "light-burned" variety used in agricultural, environmental and medical applications.

The most common magnesia-based product is known as “magnesia block.” Magnesia block is an insulation material that also contained asbestos. It was used for soldering and to make crucibles in which metals are melted down. Magnesia block products contained up to 15% asbestos by weight. Magnesia was also used to make pipe insulation.

Magnesia Products Containing Asbestos

The following partial list of magnesia products were known to contain asbestos:

Product Name Start Year End Year
AC & S Armstrong 85% Magnesia Pipe Covering 1958 1970
Celotex Carey Super-Light 85% Magnesia Pipe Covering
Fibreboard Pabco 85% Magnesia Block Insulation 1941 1971
Fibreboard Pabco 85% Magnesia Pipe Covering 1941 1971
Johns Manville 85% Magnesia Block Insulation 1902 1970
Johns Manville 85% Magnesia Pipe Covering 1902 1970
Keene Ehret Pipe Covering (85% Magnesia)

Hazards Associated with Magnesia Products

One set of major health hazards from magnesia occur during the manufacturing process, which itself requires very high heat. Magnesium oxide can give off fumes that can result in metal fume fever, which can cause very serious flu-like symptoms and is potentially fatal if not treated immediately. During the initial manufacturing process, the greatest dangers of magnesia are to the eyes and lungs. Those who work with magnesia powder must wear eye protection, as the bright light produced by burning magnesium can cause irreparable damage to the retina. Burning magnesia powder also produces toxic gases that can harm the respiratory system.

Beyond this, the major hazard from magnesia insulation products comes from the actual asbestos itself in the magnesium block or insulating sheet. During building construction, repair, renovation or demolition, these materials are capable of releasing friable asbestos fibers into the environment when they are cut to size during installation or damaged during the removal process. When inhaled, these fibers can cause mesothelioma, asbestosis and pleural thickening.



N/A. "Magnesia." Industrial Minerals Association North America ( Retrieved 26 July 2011.

N/A. "Material Safety Data Sheet: Magnesium Oxide." Fisher Scientific ( Retrieved 9 January 2011.

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