In many types of machines, when two parts are connected together by a gasket, that gasket needs to be insulated to prevent the transfer of any heat that might be generated by the moving parts. Heat seals can be found in appliances such as refrigerators, irons, washing machines and electric heaters, as well as in automobiles.
From the early 1900s through the 1970s, heat seals were often made from asbestos because this mineral had many qualities that lent itself well to the production of heat seals. In addition to being inexpensive and easy to mine, asbestos was easily formed or compressed into many different shapes; its densely packed fibers gave it incredible strength and durability, and it had excellent insulating properties against heat.
The Environmental Protection Agency (EPA) and the Consumer Product Safety Commission became concerned about the growing health risks for individuals who mined asbestos, manufactured products containing it, or worked around those products. If a gasket or heat seal containing asbestos is damaged in any way, whether it wears down from age or use or is simply cut or drilled, the tiny asbestos fibers can be released into the air. The fibers are so small that it’s easy to breathe them in, and once in the lungs they embed themselves in the lining and remain there for many years. Prolonged exposure to asbestos fibers can result in very serious diseases, including asbestosis (scarring of the lungs), lung cancer, and mesothelioma (a rare cancer of the lining of the lung).
In the late 1970s, the use of asbestos was banned for many construction and manufacturing applications; it is allowed to be used, however, in gaskets and other applications in which the fibers are tightly bound. Some foreign countries still use asbestos in a variety of products. Unfortunately, it is impossible to tell whether a gasket or heat seal contains asbestos just by looking at it.
When repairing or replacing heat seals, it is best to treat them as if they contain asbestos and proceed with extreme caution. The EPA and the Occupational Safety and Health Administration have developed guidelines for the safe removal and disposal of asbestos in many different applications. Someone who is not trained in these procedures must ensure that he or she does not carry asbestos dust on the hair, skin, clothing or shoes, where it might contaminate family members or the home. Spending some time in research and setting up a safe work area will lessen the chance of unwanted asbestos contamination.