Zonolite, Asbestos and Mesothelioma
Continued from: About Asbestos
Zonolite was produced by the W.R Grace Company as a convenient, do-it-yourself insulation material. Many homeowners used it to reduce heating and air conditioning bills during the 1970s and 1980s. It was packaged in brown bags, and consumers would typically pour it into open spaces and in between joists in the attics of homes after construction. Zonolite is brownish in color, very lightweight, with silvery or gold-colored metallic-looking material.
The primary ingredient of Zonolite is vermiculite, which is a naturally occurring mineral that has been widely used for a variety of purposes, including insulation. It has a unique exfoliation property, which means that it can expand to many times its original volume when it is heated. Thus, as an insulation material, when it becomes heated, it expands and blocks airflow around the heated area where the insulation has been placed.
Vermiculite mined in Libby, Montana, contained a rare but very dangerous form of asbestos fibers called tremolite. Even minimal handling of this type of asbestos poses a substantial health risk.
W.R. Grace mined vermiculite in Libby, Montana, during the 1960s and 1970s and packaged it as insulation under the trade name Zonolite. Grace also had a number of processing plants around the United States where it turned the mined vermiculite into Zonolite. Zonolite was sold nationwide until about 1985. The federal government estimates that it may have been used as insulation in as many as 35 million homes. The Environmental Protection Agency (EPA) warns that if Zonolite dust is inhaled, it can create significant health risks, including asbestos-related diseases.
If a homeowner suspects that Zonolite has been used in his or her home, it is best that the insulation not be disturbed. Typical activities that would disturb this harmful substance and cause asbestos dust to spill into the air would be:
- Installation of an overhead vent or fan, underneath the vermiculite insulation
- Installation of wiring into or in proximity of the vermiculite insulation
- Repairing or installing plumbing
- Installing drop-down attic stairs
- Re-insulating attic areas
- Demolition of ceilings or walls
- Demolition of a home
Inhalation of asbestos fibers present in Zonolite can lead to the development of asbestosis (lung fibrosis) or asbestos lung cancer, including malignant mesothelioma. Once Zonolite is disturbed, the asbestos fibers can fill the air and become lodged in the lungs when they are inhaled. Over time, these fibers cause scar tissue to develop in the serous membranes surrounding certain organs in the body, which can lead to asbestosis or mesothelioma cancer. Before removing or disturbing insulation, it is best to test it for asbestos contamination.
However, not even testing can guarantee that vermiculite insulation is safe for removal. Due to this uncertainty, the EPA suggests that it is best to assume that any vermiculite insulation is contaminated with asbestos. As a result, proper precautions should be taken when removing or disturbing this insulation to eliminate the potential for inhaling asbestos fibers.
Mesothelioma is a deadly form of cancer that has a very low survival rate. The time period between asbestos exposure and the onset of mesothelioma can be many decades and has been documented to be as long as 50 or 60 years. Mesothelioma symptoms can include shortness of breath and chest pain. If you are examined by a physician for these symptoms, it is best to inform the doctor if you have had previous asbestos exposure due to Zonolite insulation or from other sources.
[Page updated August 2009]