A Review of the NIOSH Roadmap for Research on Asbestos Fibers and Other Elongate Mineral Particles (2009) / Chapter Skim
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1 Introduction
1 Introduction
Pages 13-22
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From page 13... ...
Internationally, asbestos continues to be mined and used in manufacturing in a number of countries because of its desirable commercial properties such as strength and heat resistance. Ongoing issues include potential health effects in workplaces and in situ environmental settings as well as exposures to mineralogical mixtures that may contain asbestos and exposures to nonasbestiform elongate mineral particles of similar size and shape to asbestos particles.
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From page 14... ...
• Does the document clearly and adequately explain the scientific rationale for research on the mineralogy, morphology, dimen sions, and surface characteristics of elongate mineral particles, and is its treatment of this issue consistent with the state of scien tific understanding of the toxicity, occupational exposures, and epidemiology of elongate mineral particles? • Does the document discuss the most significant issues regarding mineralogy, morphology, dimensions, and surface characteristics of elongate mineral particles?
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From page 15... ...
The report concludes with Chapter 4, which provides the committee's recommendations for strengthening the Roadmap and increasing its utility for work by NIOSH, other federal agencies, the private sector, and other stakeholders. COMPLEXITIES OF THE ISSUES The following brief overview identifies several issues that highlight the challenges faced in conducting research in this field and provides some introductory material for readers unfamiliar with these topics.
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From page 16... ...
The central focus of the Roadmap is on establishing research to assess the potential for asbestos, asbestos analogs, or other mineral particles with specific physical or chemical characteristics to impact human health. The generic term elongated mineral particles is used by NIOSH in the Roadmap to encompass a broad spectrum of mineral particles of a specific size and aspect ratio but the term has no current regulatory or mineralogical connotation.
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From page 17... ...
. a NIOSH defines airborne asbestos fibers as those particles greater than 5 µm in length and having an aspect ratio of 3:1 or greater and the mineralogical characteristics (i.e., crystal structure, elemental composition)
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From page 18... ...
Within a particular mineral deposit or rock, the constituent minerals can be heterogeneous, even at the micrometer scale, varying in composition, crystal structure, and/or habit, for example. The potential diversity of minerals occurring in mineral deposits and rocks creates challenges when identifying those minerals associated with health impacts and when characterizing human exposures, whether at the mine site or during or following processing into manufactured products.
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From page 19... ...
The Roadmap acknowledges the limitations in current understanding of exposures and recommends research on the nature and levels of occupational exposures to asbestos and other elongate mineral particles and on the number of workers exposed. Further, in the United States, although generally below the levels of occupational exposures in mines, nonoccupational exposures can occur in homes, schools, public buildings, and other locations with unabated asbestos insulation or from other exposures.
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From page 20... ...
Detailed methodologies for identifying and counting asbestos fibers have been developed by NIOSH, ASTM International, the International Organization for Standardization, and other organizations using phase contrast microscopy, polarized light microscopy, scanning electron microscopy, or transmission electron microscopy. Electron microscopy methods allow higher spatial resolution and can provide further definition to the nature of the crystalline habit, previously characterized through polarized light microscopy and/or the mineral's chemical composition.
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From page 21... ...
1990a. Comments of the National Institute for Occupational Safety and Health on the Occupational Safety and Health Administration's notice of proposed rulemaking on occupational exposure to asbestos, tremolite, anthophyllite, and actinolite.
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From page 22... ...
. OSHA (Occupational Safety and Health Administration)
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