A state-of-the-science review of health hazards in insulators in the United States

This article presents a state-of-the-science analysis of the evolution of knowledge over time regarding the potential health hazards associated with exposure to airborne asbestos among the insulating trade, which included the state of knowledge of the International Association of Heat and Frost Insulators and Asbestos Workers Union (IAHFIAW), now known as the International Association of Heat and Frost Insulators and Allied Workers (IAHFIAW), and its connection to the National Insulation Contractors Association (NICA) and the National Insulation Manufacturers Association (NIMA); work practices, exposure controls, and personal protective equipment (PPE) that were recommended; and the major regulations and guidelines related to asbestos over the past 100 years in the United States (U.S.). The general timeline of knowledge regarding potential health hazards associated with insulator exposures to asbestos in the U.S. Navy is incorporated in this review, including specific examples of exposure monitoring, medical surveillance campaigns, and recommendations for work practice controls over time. This paper is divided into five time periods (late 1800s-1945; 1946-1962; 1963-1970; 1971-1981; and 1982-present) that were selected based on what were generally believed to be seminal events with respect to the recognition or knowledge of the hazards of asbestos in relation to the insulating trade, the development and standardization of workplace and respiratory controls, and the promulgation of occupational exposure limits (OELs) for asbestos. For each time period, the following topics are addressed: insulation product composition and usage; major developments in the recognition or knowledge of health hazards of asbestos, including key epidemiology studies; health studies of insulators; guidelines and regulations related to OELs for asbestos and sampling and analytical method development for characterizing exposures; and industrial hygiene sampling and recommendations for controlling exposure to asbestos during insulating operations. The goal of this analysis is to illustrate when specific scientific knowledge about asbestos health hazards was established and communicated among the scientific and industrial hygiene communities and within the IAHFIAW. Although this information is available in various separate documents and locations, the purpose of this work is to synthesize it together in a single document so that the reader can understand the full historical context of the evolution of asbestos health hazard knowledge within the insulator trade. To the best of the authors' knowledge, this review represents the most comprehensive historical examination of the literature on exposure, health effects, and industrial hygiene controls related to asbestos used in insulating operations over time.