Occupational Exposure to Carbon Nanotubes and Nanofibers

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Table 6–7 (Continued). Engineering controls to reduce CNT and CNF exposuresProcess/activityProduction and use of CNT and CNFenabled materials and compositesPotential exposure source and recommendedcontainment of exposure*Exposure Source: Mixing, weighing, and transferring of small quantities ofCNT or CNF powder or liquid suspension, including the: a) incorporationof CNT or CNF into matrices (e.g., polymer composites) and into coatings(e.g., inks) and, b) spraying CNT or CNF on surfaces.Exposure Controls: a) Laboratory fume hood (with HEPA filtered exhaustwhen warranted), b) HEPA-filtered exhausted enclosure (glove boxisolator), or c) biological safety cabinet.Exposure Source: Handling large quantities of CNT or CNF powder thatinvolves pouring and blending into other matrices. In addition, spinning,twisting, weaving of CNT into making rope, cloth, etc.; spray coating ofsurfaces.Exposure Controls: Isolation techniques such as a dedicated ventilatedroom or process enclosure with HEPA filtered exhaust. Process-basedcontrols such as ventilated bagging/weighing station, laminar down-flowbooth or non-ventilation options such as continuous liner off-loadingsystems for bagging operations. Ventilated bag dumping stations forproduct transfer.Exposure Source: Grinding, sanding, cutting, drilling or other mechanicalenergy applied to enabled-materials/composites containing CNT or CNF.Exposure Controls: For the handling of small pieces of CNT or CNFenabled materials/composites: a) laboratory fume hood (with HEPAfiltered exhaust when warranted), b) HEPA filtered exhausted enclosure(glove box isolator), or c) biological safety cabinet.Exposure Controls: For handling large CNT or CNF enabled materials/composites and where use of isolation techniques such as large ventilatedenclosures are not feasible: a) use LEV at exposure source with HEPAfiltered exhaust (may include LEV built into a hand-held tool), b) ventilateddown-flow booths with HEPA filtered exhaust, c) laboratory fume hood(with HEPA filtered exhaust) and/or d) wet dust suppression machiningtechniques such as wet saws (if applicable).*Note: Factors that influence selection of appropriate engineering controls and other exposure control strategies include thephysical form (e.g., dry dispersible powder, liquid slurry, in a matrix/composite), task duration, frequency, and quantity of CNTor CNF handled. Measurement of airborne exposure at the potential source of emission should be performed to confirm theeffectiveness of the control measure.62 NIOSH CIB 65 • Carbon Nanotubes and Nanofibers
is management commitment and support for workplacesafety [NIOSH 2010b]. The requirements forthe education and training of workers as specifiedin the OSHA Hazard Communication Standard(29 CFR 1910.1200), the Hazardous Waste Operationand Emergency Response Standard (29 CFR1910.120), and as described by Kulinowski andLippy [2011] for workers exposed to nanomaterials,provide a minimum set of guidelines that canbe used for establishing an education and trainingprogram. The establishment of a program shouldhave written procedures (e.g., standard operatingprocedures [SOPs]) for: (a) ensuring managementcommitment to control exposures, (b) identifyingand communicating potential hazards to workers,(c) assessing workplace exposures to CNT andCNF, (d) identifying and implementing engineeringand work practice controls, (e) establishingdocumentation of risk management actions taken,and (f) periodically reviewing the adequacy of controlsand other preventive practices. Managementshould systematically review and update these proceduresand convey to workers actions taken to resolveand/or improve workplace conditions.A program for educating workers should also includeboth instruction and “hands-on” trainingthat addresses the following:••The potential health risks associated with exposureto CNT and CNF.••The safe handling of CNT, CNF, and CNTandCNF-containing materials to minimizethe likelihood of inhalation exposure andskin contact, including the proper use ofengineering controls, PPE (e.g., respirators,gloves), and good work practices.6.4 Cleanup and DisposalProcedures should be developed to protect workersfrom exposure to CNT and CNF during the cleanupof CNT and CNF spills and CNT- or CNF-contaminatedsurfaces. Inhalation and dermal exposures willlikely present the greatest risks. The potential for inhalationexposure during cleanup will be influencedby the likelihood of CNT and CNF becoming airborne,with bulk CNT and CNF (powder form)presenting a greater inhalation potential than CNTand CNF in solution (liquid form), and liquids inturn presenting a greater potential risk than CNTandCNF-encapsulated materials.It would be prudent to base strategies for dealingwith spills and contaminated surfaces on the use ofcurrent good practices, together with available informationon exposure risks. Standard approachesfor cleaning powder spills can be used for cleaningsurfaces contaminated with CNT or CNF. Theseinclude using HEPA-filtered vacuum cleaners, wipingup CNT and CNF (powder form) using dampcloths, or wetting the powder before wiping. Liquidspills containing CNT or CNF can typicallybe cleaned by applying absorbent materials/liquidtraps. If vacuum cleaning is employed, care shouldbe taken that HEPA filters are installed properlyand bags and filters changed according to manufacturer’srecommendations. Dry sweeping or airhoses should not be used to clean work areas.The handling and disposal of waste (including allcleaning materials) and other contaminated materials(e.g., gloves) should comply with all applicableregulations (e.g., federal, state, local).6.5 Personal ProtectiveClothingThere are no regulations or guidelines for the selectionof protective clothing or other apparelagainst exposure to CNT and CNF; however, theOccupational Safety and Health Administration(OSHA) requires employers to provide employeeswith hand protection when exposed to hazards[OSHA 1910.138(a)]. Currently, limited informationis available to assess the exposure and healthhazards of skin exposure to CNT and CNF. In astudy to determine potential airborne and dermalexposures to SWCNT during manufacturing andhandling, workers’ dermal exposure was estimatedby placing cotton gloves over the rubber glovesused by workers [Maynard et al. 2004]. DermalNIOSH CIB 65 • Carbon Nanotubes and Nanofibers63
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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
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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 86 and 87: Table 6-6 (Continued). Examples of
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
Page 137 and 138: 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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Occupational Exposure to Carbon Nanotubes and Nanofibers

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