History of Asbestos: Mining in Libby, Montana
Continued from: Asbestos
Libby, Montana is a picturesque town that sits on a bend of the Kootenai River as it flows south from Canada toward the Columbia River. East of Libby lie the Zonolite Mountains where an asbestos mining facility was opened in 1924. More than 1,900 men worked in this mine that processed an astonishing amount of asbestos.
According to W.R. Grace and Co., who purchased the mine in 1963, at the peak of production, nearly 500,000 pounds of asbestos a day went through the "dry mill," which is the primary processing facility and the dustiest building on the property. Tests showed that as much as 24,000 pounds of dust a day were expelled from the stack on the dry mill. The dust consisted of about 20 percent asbestos. It was common for this dust to blanket the mine buildings. If a wind blew toward Libby, the dust also covered the town. It was not unusual for the clothes hanging on clotheslines to be covered with asbestos-containing dust, or for children to write their names in the dust that layered the cars.
The asbestos from the Zonolite mine was composed of tremolite. While all types of asbestos are extremely dangerous when inhaled, tremolite fibers are the most deadly. The fibers are needle-like and sharply pointed. As such, they more easily penetrate the lining of the lungs when inhaled and cause more irritation to the lung pleura. These fibers cannot be coughed or washed out, and over time the scarring of the lungs turns into a disease called asbestosis. During asbestosis, the scar tissue causes the lung to lose functioning and the patient loses his or her ability to breath. Eventually, the scar tissue completely engulfs the lungs and either the lungs fail completely or the heart becomes too overworked to continue beating.
The incidence of mesothelioma has been directly linked to tremolite and other types of asbestos exposure. Since scarring of the lungs can continue for decades after exposure to asbestos, there is a very long latency for mesothelioma. Although the mine closed in 1990, doctors from the Libby area suggest that persons from Libby will be dying from asbestos-related diseases for years to come. Indeed, x-rays taken while the mine was still operating showed that almost half of the people who had worked at the mine for 11 to 20 years had lung disease of some type. For those miners who had worked at the mine for 21 to 25 years, 92 percent showed signs of lung disease.
Asbestos exposure in Libby was highest among the mine workers, but as described earlier, the mine generated tons of asbestos-containing dust that was also a hazard to the townspeople. Further, W.R. Grace and Company, the owner of the mine, did not provide showers or a change of clothing for the miners. As a result, deadly asbestos fibers traveled from the mine to the homes of the miners in the dust on the miners' clothing. A large number of miners and family members have died in Libby due to diseases, such as malignant mesothelioma and asbestosis, caused by exposure to asbestos. The prognosis for patients with these diseases is grim. For example, the American Cancer Society places pericardial mesothelioma life expectancy, peritoneal mesothelioma life expectancy and pleural mesothelioma life expectancy at between four and 18 months.
In addition to the asbestos deposits, the Libby area also has enormous deposits of vermiculite. In the area of the vermiculite deposits, tremolite asbestos laid undisturbed under a thin layer of top soil. When the vermiculite mining started, these deadly asbestos fibers were released into the air. In 1999, statistics showed that 12 to 15 people a month from Libby were being diagnosed with the asbestos related diseases asbestosis, mesothelioma and lung cancer.
Although the vermiculite mines are closed in Libby, vermiculite that derived from the Libby mines may continue to pose a health risk. Vermiculite is used in insulation and construction materials. If these materials were used in a structure and then become disturbed during demolition or other movement, the asbestos fibers can become airborne. When airborne, these fibers can be inhaled and then penetrate the lining of the lung. Tremolite asbestos fibers are particularly sharp and needle-like, thus causing more lung penetration and irritation with fewer fibers.
In cases where asbestos-containing vermiculite must be removed, standard hazardous material handling protocols should be used. Before removing and destroying any construction materials, it is best to have them tested for asbestos.
[Page updated May 2011]