EVALUATION OF PAST, PRESENT, AND FUTURE EXPOSURES TO ASBESTOS AND THE RELATED RISK OF DISEASE

Asbestos is a commercial term that commonly refers to one or more members in a group of six naturally-occurring, hydrated silicate minerals. This group includes actinolite, amosite, anthophyllite, chrysotile, crocidolite, and tremolite. To further designate morphology or chemical composition, descriptors or other distinct names have also been assigned to these six minerals. Consequently, there has been some confusion associated with the nomenclature for asbestos. In contrast, the intrinsic properties of asbestos, such as durability, flexibility, friability, stability, and tensile strength are well-known, accounting for its high commercial value and its use as an insulating and reinforcing material throughout the world. Over the past 30 or more years, many publications have described the assessment of exposures to asbestos and the related risk of disease. Epidemiological studies, for example, have focused on cement workers, insulation workers, shipbuilders, and miners. From this scientific literature, the U.S. Occupational Safety and Health Administration (OSHA) identified an increased risk of mortality from lung cancer and mesothelioma, as well as an increased incidence of asbestosis, following chronic exposure to asbestos. In 1994, OSHA published a final rule that lowered its Permissible Exposure Limit for specific forms of asbestos to 0.1 fiber per cubic centimeter of air. This airborne exposure limit has been adopted by other agencies within the U.S. and in other countries. However, concerns still remain regarding the risk of disease from asbestos exposure, not only in occupational settings, but in environmental settings. Questions have been raised about the current definition of asbestos, applicability of OSHA's risk assessment, analytical methodologies, and exposure limits for asbestos, among a plethora of other technical issues. Some organizations have advocated an international ban of asbestos. Thus, regulators and policy-makers throughout the world face a considerable challenge in addressing the multi-faceted aspects of asbestos exposure and related risk of disease.