Assessing Exposure to Airborne Nanomaterials

Speaker:

Robert Aitken Director, Strategic Consulting, Institute of Occupational Medicine

Co-Author(s):

Miss Bryony Ross, Institute of Occupational Medicine

Classically, occupational exposure to airborne particles has been characterised in terms of the mass of material present per unit volume (mg/m3). Measurements are based on the workers breathing zone and are taken using personal samplers developed using guidance on inhalable, thoracic, respirable fractions provided in ISO 7708 (1995). Measurement of high aspect ratio particles such as fibres is however based on a different approach and requires counting of these particles to achieve a number concentration. However, the applicability of these traditional approaches to assessment of exposure to nanoparticles is questionable based on published associations between particle toxicity and surface area. A wide range of sampling methods exist, including those which measure mass, particle number, surface area etc. However, in all cases there are limitations in applying these directly to nanoparticle exposure. As a result, there is very little published data concerning assessment of exposure to airborne engineered nanomaterials and the area is currently not well understood. Classification of engineered nanoparticles according to their physicochemical characteristics, and relation of these to health impact-relevant attributes to explore the applicability of different physical exposure metrics to a range of particle class/attribute combinations has been investigated in a recent review by Maynard and Aitken (2007) and this can help with the election of appropriate methods. In this paper we provide a critical review of the methods available for measurement of exposure to engineered nanoparticles and a discussion of their applications and limits, based on recent experimental evidence. References: Maynard A.D. and Aitken R.J. (2007). Assessing exposure to airborne nanomaterials: Current abilities and future requirements. Nanotoxicology 1:26-41.