UNLABELLED: RESEARCH SIGNIFICANCE: Toxicological evidence suggests the potential for a wide range of health effects, which could result from exposure to carbon nanotubes (CNTs) and carbon nanofibers (CNFs). The National Institute for Occupational Safety and Health (NIOSH) has proposed a recommended exposure limit (REL) for CNTs/CNFs at the respirable size fraction. The current literature is lacking exposure information, with few studies reporting results for personal breathing zone (PBZ) samples in occupational settings. To address this gap, exposure assessments were conducted at six representative sites identified as CNT/CNF primary or secondary manufacturers. METHODS: Personal and area filter-based samples were collected for both the inhalable mass concentration and the respirable mass concentration of elemental carbon (EC) as well as CNT structure count analysis by transmission electron microscopy to assess exposures. When possible, full-shift PBZ samples were collected; area samples were collected on a task-based approach. RESULTS: The vast majority of samples collected in this study were below the proposed REL (7 μg m(-3)). Two of the three secondary manufacturers' surveyed found concentrations above the proposed REL. None of the samples collected at primary manufacturers were found to be above the REL. Visual and microscopy-based evidence of CNTs/CNFs were found at all sites, with the highest CNT/CNF structure counts being found in samples collected at secondary manufacturing sites. The statistical correlations between the filter-based samples for the mass concentration of EC and CNT structure counts were examined. A general trend was found with a P-value of 0.01 and a corresponding Pearson correlation coefficient of 0.44. CONCLUSIONS: CNT/CNF concentrations were above the proposed NIOSH REL for PBZ samples in two secondary manufacturing facilities that use these materials for commercial applications. These samples were collected during dry powder handling processes, such as mixing and weighing, using fairly large quantities of CNTs/CNFs.
UNLABELLED: RESEARCH SIGNIFICANCE: Toxicological evidence suggests the potential for a wide range of health effects, which could result from exposure to carbon nanotubes (CNTs) and carbon nanofibers (CNFs). The National Institute for Occupational Safety and Health (NIOSH) has proposed a recommended exposure limit (REL) for CNTs/CNFs at the respirable size fraction. The current literature is lacking exposure information, with few studies reporting results for personal breathing zone (PBZ) samples in occupational settings. To address this gap, exposure assessments were conducted at six representative sites identified as CNT/CNF primary or secondary manufacturers. METHODS: Personal and area filter-based samples were collected for both the inhalable mass concentration and the respirable mass concentration of elemental carbon (EC) as well as CNT structure count analysis by transmission electron microscopy to assess exposures. When possible, full-shift PBZ samples were collected; area samples were collected on a task-based approach. RESULTS: The vast majority of samples collected in this study were below the proposed REL (7 μg m(-3)). Two of the three secondary manufacturers' surveyed found concentrations above the proposed REL. None of the samples collected at primary manufacturers were found to be above the REL. Visual and microscopy-based evidence of CNTs/CNFs were found at all sites, with the highest CNT/CNF structure counts being found in samples collected at secondary manufacturing sites. The statistical correlations between the filter-based samples for the mass concentration of EC and CNT structure counts were examined. A general trend was found with a P-value of 0.01 and a corresponding Pearson correlation coefficient of 0.44. CONCLUSIONS: CNT/CNF concentrations were above the proposed NIOSH REL for PBZ samples in two secondary manufacturing facilities that use these materials for commercial applications. These samples were collected during dry powder handling processes, such as mixing and weighing, using fairly large quantities of CNTs/CNFs.
Authors: L M Sargent; A A Shvedova; A F Hubbs; J L Salisbury; S A Benkovic; M L Kashon; D T Lowry; A R Murray; E R Kisin; S Friend; K T McKinstry; L Battelli; S H Reynolds Journal: Environ Mol Mutagen Date: 2009-10 Impact factor: 3.216
Authors: Ken Donaldson; Robert Aitken; Lang Tran; Vicki Stone; Rodger Duffin; Gavin Forrest; Andrew Alexander Journal: Toxicol Sci Date: 2006-02-16 Impact factor: 4.849
Authors: Dale W Porter; Ann F Hubbs; Robert R Mercer; Nianqiang Wu; Michael G Wolfarth; Krishnan Sriram; Stephen Leonard; Lori Battelli; Diane Schwegler-Berry; Sherry Friend; Michael Andrew; Bean T Chen; Shuji Tsuruoka; Morinobu Endo; Vincent Castranova Journal: Toxicology Date: 2009-10-24 Impact factor: 4.221
Authors: Craig A Poland; Rodger Duffin; Ian Kinloch; Andrew Maynard; William A H Wallace; Anthony Seaton; Vicki Stone; Simon Brown; William Macnee; Ken Donaldson Journal: Nat Nanotechnol Date: 2008-05-20 Impact factor: 39.213
Authors: Dale W Porter; Marlene Orandle; Peng Zheng; Nianqiang Wu; Raymond F Hamilton; Andrij Holian; Bean T Chen; Michael Andrew; Michael G Wolfarth; Lori Battelli; Shuji Tsuruoka; Mauricio Terrones; Vince Castranova Journal: Inhal Toxicol Date: 2020-02-07 Impact factor: 2.724
Authors: Eileen D Kuempel; Marie-Claude Jaurand; Peter Møller; Yasuo Morimoto; Norihiro Kobayashi; Kent E Pinkerton; Linda M Sargent; Roel C H Vermeulen; Bice Fubini; Agnes B Kane Journal: Crit Rev Toxicol Date: 2016-08-18 Impact factor: 5.635
Authors: Matthew M Dahm; Mary K Schubauer-Berigan; Douglas E Evans; M Eileen Birch; Joseph E Fernback; James A Deddens Journal: Ann Occup Hyg Date: 2015-04-07