U.S. EPA may be in the midst of changing the basic assumptions in its 1986 risk assessment model for asbestos. Currently, EPA’s risk assessment model considers all asbestos mineral types and all asbestos fibers greater than five microns in length to be equally capable of causing mesothelioma and lung cancer.
The model is under intense attack from industry types and insurers, who want to do away with EPA’s assumption that all asbestos fibers greater than five microns in length are dangerous to humans. However, changing underlying assumptions in the model would be a radical change for EPA. Since 1986, EPA’s approach to assessing disease risk from asbestos exposures drew no distinctions among fiber types or fiber sizes.
Many different kinds of asbestos were used in building materials, paper products, plastics, and other products. The principal forms of asbestos include chrysotile, crocidolite, amosite, tremolite, actinolite, and anthophyllite. All but chrysotile are classified as amphiboles, which tend to have a thin, needle-like appearance.
Exposure mainly occurs in indoor air where it may be released from asbestos-containing materials. Effects on the lung are a major health concern from asbestos, as chronic exposure to asbestos in humans via inhalation can result in asbestosis.
Cancer is also a major concern from asbestos exposure, as inhalation exposure can cause lung cancer and mesothelioma (a rare cancer of the thin membranes lining the abdominal cavity and surrounding internal organs), and possibly gastrointestinal cancers in humans.
U.S. EPA has classified asbestos as a Group A, known human carcinogen. Asbestos litigation has swelled in recent years and many companies are facing millions of dollars in potential liability and cleanups.
If a new risk assessment model for asbestos is approved by EPA, the new model would likely classify chrysotile asbestos as a lower risk of harm than other types of asbestos minerals. There is really no secret to the underlying rationale for this change. Chrysotile was the most widely used type of asbestos in the U.S.
To the skeptical, EPA is under pressure to change a basic assumption in its risk assessment model to reduce the financial risk to defendants in asbestos litigation and cleanup, rather than as a result of new or convincing scientific evidence on the topic.