Asbestos is a naturally occurring fibrous material that resists fire and most solvents. Asbestos is a toxic material, and occupational exposure to asbestos dust can result in mesothelioma, asbestosis, and lung cancer. D began these proceedings in 1979 when it issued an Advanced Notice of Proposed Rulemaking announcing its intent to explore the use of TSCA 'to reduce the risk to human health posed by exposure to asbestos.' D appointed a panel and reviewed over one hundred studies of asbestos and conducted several public meetings. D concluded that asbestos is a potential carcinogen at all levels of exposure, regardless of the type of asbestos or the size of the fiber. In 1989, D issued a final rule prohibiting the manufacture, importation, processing, and distribution in commerce of most asbestos-containing products. D estimates that this rule will save either 202 or 148 lives, depending upon whether the benefits are discounted, at a cost of approximately $450-800 million, depending upon the price of substitutes. Ps allege that D did not cross-examining Ps' witnesses, did not assemble a panel of experts on asbestos disease risks, designated a hearing officer, rather than an administrative law judge (ALJ), to preside at the hearings on the rule, and did not swear in witnesses who testified. D did not allow cross-examination of some of its witnesses and did not notify anyone until after the hearings were over that it intended to use 'analogous exposure' estimates and a substitute pricing assumption to support its rule.