Occupational Exposure to Carbon Nanotubes and Nanofibers

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Table 6–6 (Continued). Examples of engineering controlsContainment categoryand description Advantages DisadvantagesD. Closed process design(isolation)All steps of the process or jobtask are sealed with little chanceof worker exposure.Examples:D.1. Glove box isolators (withHEPA filtered exhaust)D.2. Biological safety cabinetclass IIIEmission source confined.Minimizes external contamination.Need for worker PPE (e.g., respirator)reduced.More time required moving materialsand equipment in and out of enclosure.Difficulty in manipulating materialswhen wearing gloves.Limitations on size of material that canbe placed inside of an isolator.Need to periodically clean theenclosure.Adapted from Industrial Ventilation [ACGIH 2007]60 NIOSH CIB 65 • Carbon Nanotubes and Nanofibers
Table 6–7. Engineering controls to reduce CNT and CNF exposuresProcess/activityA. Pilot and research developmentoperationsPotential exposure source and recommendedcontainment of exposure*Exposure Source: Synthesis of CNT and CNF by fluidized-bed, chemicalvapor deposition, etc.: a) collection/harvesting after synthesis, b) powdertransfer, c) cleaning reactor, d) removal of CNT and CNF from a substrate,e) purification and/or functionalization of CNT or CNF [note: potentialexposures are generally to small quantities of CNT and CNF (i.e., µg,mg) compared to exposure to larger amounts (e.g., kg) during full-scalemanufacturing/synthesis (see C below)].Exposure Controls: a) laboratory fume hood (with HEPA filtered exhaustwhen warranted), b) HEPA-filtered exhausted enclosure (glove box), or c)biological safety cabinet. Local exhaust ventilation (LEV) may be requiredwhen opening reactor and during harvesting.B. Research laboratories Exposure Source: Handling (e.g., mixing, weighing, blending, transferring)small quantities (e.g., µg, mg) of CNT or CNF powder or during sonicationof a CNT or CNF liquid suspension.Exposure Controls: a) laboratory fume hood (with HEPA filtered exhaustwhen warranted), b) HEPA-filtered exhausted enclosure (glove boxisolator), or c) biological safety cabinet.C. CNT and CNF manufacturingand synthesisExposure Source: Synthesis of CNT and CNF by fluidized-bed, chemicalvapor deposition, etc., including: a) collection/harvesting after synthesis,b) drum and bag filling, c) powder transfer, d) cleaning reactor, e) removalof CNT and CNF from a substrate, f) purification and/or functionalizationof CNT or CNF [Note: potential exposures are generally to large quantities(e.g., kg) of CNT and CNF].Exposure Controls: Dedicated ventilated room with HEPA filtered exhaust,and/or LEV at source of exposure with HEPA filtered exhaust. Examples:ventilated bagging/weighing station and/or laminar down-flow booth ornon-ventilation options such as continuous liner off-loading systems forbagging operations. Ventilated bag dumping stations for product transfer.See footnotes at end of table.(Continued)NIOSH CIB 65 • Carbon Nanotubes and Nanofibers61
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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
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••Follow exposure and hazard as
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Periodic Evaluations••Evaluatio
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ContentsForeword ..................
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A.3.2 Comparison of Short-term and
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ESPFeFMPSFPSSgGMGSDHCLHECHEPAhrISOI
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AcknowledgementsThis Current Intell
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1 IntroductionMany nanomaterial-bas
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2 Potential for ExposureThe novel a
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CNMs, with MWCNT agglomerates obser
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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 and 66: A-6). Risk estimates derived from o
Page 67 and 68: Table 5-4. Factors, assumptions, an
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 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
Page 119 and 120: ContentsA.1 Introduction ..........
Page 121 and 122: A.1 IntroductionThe increasing prod
Page 123 and 124: provide an informal check on the es
Page 125 and 126: these same dose groups; this effect
Page 127 and 128: Table A-1. Rodent study information
Page 129 and 130: the deposited (no clearance) and th
Page 131 and 132: The other BMDS models failed to con
Page 133 and 134: Figure A-2. Benchmark dose model (m
Page 135 and 136: 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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