Evaluation of total and inhalable samplers for the collection of carbon nanotube and carbon nanofiber aerosols

Abstract

A growing number of carbon nanotubes and nanofibers (CNT/F) exposure and epidemiologic studies have utilized 25-and 37-mm open-faced cassettes (OFCs) to assess the inhalable aerosol fraction. It has been previously established that the 37-mm OFC undersamples particles >20 mm in diameter, but the size-selective characteristics of the 25-mm OFC have not yet been fully evaluated. This article describes an experimental study conducted to determine if the 25-and 37-mm OFCs performed with relative equivalence to a reference inhalable aerosol sampler when challenged with CNT/F particles. Side-by-side paired samples were collected within a small Venturi chamber using a 25-mm styrene OFC, 37-mm styrene OFC, 25-mm aluminum OFC, and button inhalable aerosol sampler. Three types of CNT/F materials and an Arizona road dust were used as challenge aerosols for the various sampler configurations. Repeated experiments were conducted for each sampler configuration and material. The OFC samplers operated at flow rates of 2 and 5 L/min. Results showed that the 25-mm OFC performed comparably to the button sampler when challenged with CNT/F aerosols, which was demonstrated in five of the six experimental scenarios with an average error of 21%. Overall, the results of this study indicate that the sampling efficiency of the 25-and 37-mm OFCs adequately followed the ISO/ACGIH/CEN inhalable sampling convention when challenged with CNT/F aerosols. Past exposure and epidemiologic studies that used these OFC samplers can directly compare their results to studies that have used other validated inhalable aerosol samplers.

Physicochemical characterization and genotoxicity of the broad class of carbon nanotubes and nanofibers used or produced in U.S. facilities

“…Total dustiness was the percent of the total dust (sample using a closed face cassette) that can be aerosolized from the test sample, while the respirable fraction (sampled with a cyclone) was the percent of the aerosolized dust that can penetrate to the deep airways, or the alveolar region. Total dustiness may be approximated to the inhalable dustiness fraction, particularly with these CNT/F materials [ 94 ] MW #1, #2, #5, and CNF #1 had total dustiness that ranged from 3 to 14% and a respirable dustiness that ranged from 0.8–2.4%. CNF #2 was not measured but was expected to be very close to the values of CNF #1 and MW #5 published previously [ 93 ].…”