Occupational Exposure to Carbon Nanotubes and Nanofibers

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Table 5–3. Summary of human-equivalent working lifetime exposure concentration estimatesassociated with animal effect levelsWorking lifetime 8-hr TWA (µg/m 3 )Animaleffect levelAnimal lung responseAssumingestimateddepositedlung dose *Assumingestimatedretainedlung dose *Animal studyTablein CIBNOAELNo statistically significantlung responseSubchronic studiesnd 3.5 Pauluhn 2010a A–13LOAELMinimal granulomatousinflammation (grade 1+)nd 4.0 Ma-Hock et al.2009A–13BMD 10Minimal granulomatousinflammation or alveolarseptal thickening (grade 1+)0.51, 0.77 2.7, 4.2 Ma-Hock et al.2009; Pauluhn2010a, respectivelyBMDL 100.19, 0.38 1.0, 1.9A–5BMD 10Slight/mild granulomatousinflammation or alveolarseptal thickening (grade 2+)BMDL 100.69, 3.3 4, 191.0, 6.4 6.2, 44 Ma-Hock et al.2009; Pauluhn2010a, respectivelyA–6Short-term studiesBMD 10BMDL 10Alveolar connective tissuethickness0.11, 1.8, 4.70.075, 1.0, 2.5nd Shvedova et al.2005; Mercer etal. 2011; Shvedovaet al. 2008,respectivelyA–3BMD 10Hydroxyproline amount 18 nd Muller et al. 2005 A–3BMDL 1012BMD 10BMDL 10Granuloma 101.7nd Lam et al. 2004 A–4Abbreviations: nd=not determined; BMD 10=benchmark dose (maximum likelihood estimate) associated with 10% additional riskof the adverse response; BMDL 10=95% lower confidence limit estimate of the BMD 10; LOAEL= lowest observed adverse effectlevel; NOAEL=No observed adverse effect level*Interspecies dose normalized by alveolar surface area in animal and humans (Section A.2.3.4).40 NIOSH CIB 65 • Carbon Nanotubes and Nanofibers
Table 5–4. Factors, assumptions, and options evaluated in the CNT risk assessment.CNT typeRoute of exposureDuration of exposureFactor Assumption Options evaluatedRisk estimates for various types ofCNT are relevant to worker exposures,based on animal dose-response data ofadministered or estimated lung dose andearly-stage, persistent lung responses, usingstandardized methodsLung dose is associated with animalresponse regardless of route of exposureand is relevant to human inhaled doseSubchronic or short-term exposure isassociated with observed lung responsesand relevant to humansSWCNT (Fe 2%)SWCNT (Fe 0.2–0.3%)SWCNT (Fe 18%)MWCNT (Co 2%, Fe 0.5%)MWCNT (Al 2O 39.6%)MWCNT (Co 0.5%)InhalationPharyngeal aspirationIntratracheal instillation13-week inhalation, 1d–26wk PEShort-term inhalation, 56d PESingle dose, 28–91d PESpecies/strain Animal model is relevant for humans Rat• Sprague-Dawley• Wistar• Mouse• B6C3F1• C57BL/6Sex No sex-specific effect MaleFemaleCritical effect Animal response is relevant to humans Dichotomous response:GranulomaGranulomatous inflammation *• grade 1+• grade 2+Lipoproteinosis• grade 1+Alveolar septal thickening• grade 1+• grade 2Continuous response:Alveolar connective tissue (septal)thicknessHydroxyproline amountCritical effect levelDose to target tissue (as administered,estimated deposited, or estimated retainedmass in alveolar region of lungs) isassociated with lung responseBMDLBMDNOAELLOAELSee footnotes at end of table.(Continued)NIOSH CIB 65 • Carbon Nanotubes and Nanofibers41
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CURRENT INTELLIGENCE BULLETIN 65Occ
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Current Intelligence Bulletin 65Occ
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ForewordThe Occupational Safety and
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Executive SummaryOverviewCarbon nan
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2009; Pauluhn 2010a; Porter et al.
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neurogenic sig nals from sensory ir
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possible. Until the results from an
Page 15 and 16: ••Follow exposure and hazard as
Page 17 and 18: Periodic Evaluations••Evaluatio
Page 19 and 20: ContentsForeword ..................
Page 21 and 22: A.3.2 Comparison of Short-term and
Page 23 and 24: ESPFeFMPSFPSSgGMGSDHCLHECHEPAhrISOI
Page 25 and 26: AcknowledgementsThis Current Intell
Page 27 and 28: 1 IntroductionMany nanomaterial-bas
Page 29: 2 Potential for ExposureThe novel a
Page 32 and 33: CNMs, with MWCNT agglomerates obser
Page 34 and 35: composite materials with local exha
Page 36 and 37: information on air contaminants. Sa
Page 39 and 40: 3 Evidence for Potential Adverse He
Page 41 and 42: decreasing agglomerate size increas
Page 43 and 44: examined up to 60 days post-exposur
Page 45 and 46: 3.3 SWCNT and MWCNTIntraperitoneal
Page 47 and 48: The same potency sequence was obser
Page 49 and 50: Table 3-3. Findings from published
Page 55 and 56: Table 3-7 (Continued). Findings fro
Page 57: Table 3-8. Findings from published
Page 60 and 61: length, respectively) [Muller et al
Page 63 and 64: 5 CNT Risk Assessment and Recommend
Page 65: A-6). Risk estimates derived from o
Page 69 and 70: and analytical methods. NIOSH is re
Page 71 and 72: Table 5-5. Recommended occupational
Page 73 and 74: deficits in animals or clinically s
Page 75: (3) Rat lung dose estimationIn the
Page 78 and 79: tasks where worker exposures exceed
Page 80 and 81: As part of the evaluation of worker
Page 82 and 83: Table 6-1. EC LODs and LOQs for 25-
Page 84 and 85: 6.2 Engineering ControlsOne of the
Page 86 and 87: Table 6-6 (Continued). Examples of
Page 88 and 89: Table 6-7 (Continued). Engineering
Page 90 and 91: exposure estimates for SWCNT on ind
Page 92 and 93: Table 6-8. Respiratory protection f
Page 94 and 95: ••Workers in areas or in jobs w
Page 97 and 98: 7 Research NeedsAdditional data and
Page 99 and 100: ReferencesACGIH [1984]. Particle si
Page 101 and 102: Bolton RE, Vincent HJ, Jones AD, Ad
Page 103 and 104: eport issued on July 22, 2011. NEDO
Page 105 and 106: Kobayashi N, Naya M, Mizuno K, Yama
Page 107 and 108: Methner M, Hodson L, Geraci C [2010
Page 109 and 110: Human Services, Centers for Disease
Page 111 and 112: Piegorsch WW, Bailer AF [2005]. Qua
Page 113 and 114: AD, Baron PA [2003]. Exposure to ca
Page 115: Varga C, Szendi K [2010]. Carbon na
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ContentsA.1 Introduction ..........
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A.1 IntroductionThe increasing prod
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provide an informal check on the es
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these same dose groups; this effect
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Table A-1. Rodent study information
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the deposited (no clearance) and th
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The other BMDS models failed to con
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Figure A-2. Benchmark dose model (m
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Figure A-3 (continued). Benchmark d
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Table A-3. Benchmark dose estimates
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Table A-5. Benchmark dose estimates
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histopathology grade 2 or higher lu
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Table A-8. Working lifetime percent
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developing early-stage adverse lung
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Figure A-4. Dose-response relations
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cell surface area). However, the wo
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purified or unpurified (with differ
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Table A-9. Comparison of rat or hum
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A.6.1.3 Pulmonary Ventilation RateT
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used as the effect levels in evalua
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the DF estimate, although a larger
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or overloading, of particle clearan
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Table A-13. Human-equivalent retain
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A.7.1 Particle CharacteristicsBoth
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and density. The following MMAD and
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Table A-15. CNT lung dose normalize
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B.1 Key Terms Related toMedical Sur
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APPENDIX CNIOSH Method 5040
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filter. In the method evaluation, d
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Most of the studies on sampling art
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e analyzed to determine the onset o
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Delivering on the Nation’s promis
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