1.1 This guide describes actions that could be taken by the user to minimize human exposures to unbound, engineered nanoscale particles (UNP) in research, manufacturing, laboratory and other occupational settings where UNP may reasonably be expected to be present. It is intended to provide guidance for controlling such exposures as a cautionary measure where neither relevant exposure standards nor definitive hazard and exposure information exist.

1.2 General Guidance—This guide is applicable to occupational settings where UNP may reasonably be expected to be present. Operations across those settings will vary widely in the particular aspects relevant to nanoscale particle exposure control. UNP represent a vast variety of physical and chemical characteristics (for example, morphology, mass, dimension, chemical composition, settling velocities, surface area, surface chemistry) and circumstances of use. Given the range of physical and chemical characteristics presented by the various UNP, the diversity of occupational settings and the uneven empirical knowledge of and experience with handling UNP materials, the purpose of this guide is to offer general guidance on exposure minimization approaches for UNP based upon a consensus of viewpoints, but not to establish a standard practice nor to recommend a definite course of action to follow in all cases.

1.3 Applicable Where Robust Risk Information Does Not Exist—This guide assumes the absence of scientifically sound risk assessment information relevant to the particular UNP involved. Where sound risk assessment information exists, or comes to exist, any exposure control measures should be designed based on that information, and not premised on this guide. Such measures may be more or less stringent than those suggested by this guide.

1.4 Materials Within Scope—This guide pertains to unbound engineered nanoscale particles or their respirable agglomerates or aggregates thereof. Relevant nanoscale particle types include, for example, intentionally produced fullerenes, nanotubes, nanowires, nanoropes, nanoribbons, quantum dots, nanoscale metal oxides, and other engineered nanoscale particles. Respirable particles are those having an aerodynamic equivalent diameter (AED) less than or equal to 10 µm (10 000 nm) or those particles small enough to be collected with a respirable sampler (1-3).² The AED describes the behavior of an airborne particle and is dependent upon the particle density, shape, and size—for instance, a particle with a spherical shape, smooth surface, density of 1.0 g/cc and a physical diameter of 4 µm would have an AED of 4 µm, whereas a particle with a spherical shape, smooth surface, density of 11.35 g/cc and a physical diameter of 4 µm would have an AED of 14 µm and would therefore be of a nonrespirable size. Respirable fibers are those having physical diameters less than or equal to 3 µm (3000 nm) or those fibers small enough to be collected with a thoracic sampler (4, 5).

1.5 Materials Beyond Scope:

1.6 Handling Considerations Beyond Scope—The use of this guide is limited to the scope set forth in this section. This guide generally does not address actions related to potential environmental exposures, nor to exposures potentially arising at disposal or other end-uses.

1.7 Not a Standard of Care—This guide does not necessarily represent the standard of care by which the adequacy of a set of exposure control measures should be judged; nor should this document be used without consideration of the particular materials and occupational circumstances to which it may be applied. The word “standard” in the title means only that the document has been approved through the ASTM consensus process.

1.8 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.9 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.