"Background Efforts have been made for 25 years to develop asbestos risk assessments that provide valid information about workplace and community cancer risks. Mathematical models have been applied to a group of workplace epidemiology studies to describe the relationships between exposure and risk. EPA's most recent proposed method was presented at a public meeting in July 2008.Methods Risk assessments prepared by USEPA, OSHA, and NIOSH since 1972 were reviewed, along with related literature. Results and Conclusions None of the efforts to use statistical models to characterize relative cancer potencies for asbestos fiber types and sizes have been able to overcome limitations of the exposure data. Resulting uncertainties have been so great that these estimates should not be used to drive occupational and environmental health policy. The EPA has now rejected and discontinued work on its proposed methods for estimating potency factors. Future efforts will require new methods and more precise and reliable exposure assessments. However, while there may be genuine need for such work, a more pressing priority with regard to the six regulated forms of asbestos and other asbestiform fibers is to ban their production and use."

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