In a report titled “Elimination of Asbestos Related Diseases”, published in September 2006, the World Health Organization said that increased cancer risks have been observed in populations exposed to very low levels of asbestos. It further stated that they only efficient way to eliminate all asbestos-related disease was the discontinued use of asbestos.
International Trade Union Calls for the Use of Asbestos Alternatives
The Building and Woodworker’s International (BWI) says that 90 percent of all asbestos use is in asbestos-cement products and seven percent is in friction materials such as various types of rubber and resin that are used as binders.
Plastic materials that have been augmented with a binder created from rubber with an asbestos base have a greater and more stable coefficient of friction, making them especially desirable for motor vehicle brake linings and clutch bands. These plastic materials can also be created with an asbestos-based resin binder, but the friction coefficient is lower.
Experts Gather to Assess the Toxicity of Chrysotile Asbestos Alternatives
In November 2005, WHO convened a workshop at its subdivision, the International Agency for Research on Cancer (IARC) in Lyon, France. The purpose of this meeting was to evaluate the suitability of 12 chrysotile asbestos substitutes.
The following list indicates how the organization grouped these substitutes in terms of hazard level:
- Para-Aramid releases respirable fibers (fibers that can be easily inhaled) that have a size that is equivalent to known carcinogens. These fibers have been shown to have harmful effects on the lungs in animal studies and they are considered a medium risk.
- Attapulgite fiber hazard was deemed high for long fibers and low for short fibers based on observations from long-term inhalation studies using animals.
- Carbon fiber exposure in the workplace is primarily to non-respirable fiber, making this a low hazard.
- Cellulose fiber posed a problem in terms of a definitive hazard classification. Most of these fibers are non-respirable, making them low hazard. However, there are some cellulose fibers that are respirable, but there is no exiting data available to assess their toxicity. Therefore, the evaluation for cellulose was deemed indeterminate.
- Graphite whiskers fibers are extremely respirable and they have a long half life in the lungs. A half life is the length of time it would take graphite whiskers to decay enough to increase the original amount inhaled by half. However, the evaluation for graphite whiskers was deemed indeterminate because of the scarcity of information on the substance.
- Magnesium sulphate whiskers did not cause tumors with limited inhalation according to various short-term tests and they are quickly expelled from the lungs. In spite of this, no consensus of opinion could be reached as to whether this fiber is a low or indeterminate risk.
- Polyethylene polyvinyl chloride fibers was classified as indeterminate because of the lack of available data to make an evaluation.
- Polypropylene fibers are respirable and they remain in the lungs for a long time. However, in animal studies, there was no evidence of fibrosis, which is the formation of scar tissue. The classification of this fiber was indeterminate because of the limited number of studies.
- Potassium octatitanate fibers poses a high threat because they are respirable in the workplace and they remain in the lungs for a long time. In addition, there was evidence of high increase of risk for mesothelioma when the fibers were injected into the abdominal cavity during testing.
- Synthetic vitreous fibers (glass wool/fibrous glass, mineral wool, special purpose vitreous silicates and refractory ceramic fibers) posed a classification problem. Based on inhalation studies, studies in which the fibers were injected into the abdominal cavity and studies concerning the length of time the fibers remain in the lungs, these fibers were classified as high for those that remained in the lungs for a long time and low for those that didn’t.
- Wollastonite was considered a low hazard because occupational exposure is primarily to short fibers and it didn’t produce tumors in animal tests during which fibers were injected into the abdominal cavity.
- Xonotlite is rapidly expelled from the lungs and it didn’t cause tumors when injected into the abdominal cavity. Studies in which the fiber was injected into the trachea showed no evidence of inflammation or creation of scar tissue in the lungs. Therefore, it was classified as low hazard.