Effect of carbon nanotubes upon emissions from cutting and sanding carbon fiber-epoxy composites

Heitbrink, William A.; Lo, Li-Ming

doi:10.1007/s11051-015-3140-0

Cited by 6 publications

(4 citation statements)

References 51 publications

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“…Bello et al showed that the use of wet suppression techniques during sawing of nanocomposites reduced exposures down to background levels (Bello et al 2009). A recent study has also shown that the ventilated enclosure built to contain a power sawing machine efficiently captured the dust generated by cutting and sanding nanocomposite panels (Heitbrink and Lo 2015). …”

Section: Resultsmentioning

confidence: 99%

Performance of particulate containment at nanotechnology workplaces

Tsai

Dunn

et al. 2015

J Nanopart Res

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The evaluation of engineering controls for the production or use of carbon nanotubes (CNTs) was investigated at two facilities. These controls assessments are necessary to evaluate the current status of control performance and to develop proper control strategies for these workplaces. The control systems evaluated in these studies included ventilated enclosures, exterior hoods, and exhaust filtration systems. Activity-based monitoring with direct-reading instruments and filter sampling for microscopy analysis were used to evaluate the effectiveness of control measures at study sites. Our study results showed that weighing CNTs inside the biological safety cabinet can have a 37% reduction on the particle concentration in the worker’s breathing zone, and produce a 42% lower area concentration outside the enclosure. The ventilated enclosures used to reduce fugitive emissions from the production furnaces exhibited good containment characteristics when closed, but they failed to contain emissions effectively when opened during product removal/harvesting. The exhaust filtration systems employed for exhausting these ventilated enclosures did not provide promised collection efficiencies for removing engineered nanomaterials from furnace exhaust. The exterior hoods were found to be a challenge for controlling emissions from machining nanocomposites: the downdraft hood effectively contained and removed particles released from the manual cutting process, but using the canopy hood for powered cutting of nanocomposites created 15%–20% higher ultrafine (<500 nm) particle concentrations at the source and at the worker’s breathing zone. The microscopy analysis showed that CNTs can only be found at production sources but not at the worker breathing zones during the tasks monitored.

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Section: Resultsmentioning

confidence: 99%

Performance of particulate containment at nanotechnology workplaces

Tsai

Dunn

et al. 2015

J Nanopart Res

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“…Information regarding CNTs emissions in working environments is still limited (Methner et al 2010; Heitbrink and Lo 2015; Heitbrink et al 2015). The goal of this study is to assess nanomaterial emissions from product development activities in a laboratory and contribute additional understanding about potential CNT exposure and effective control measures.…”

Section: Introductionmentioning

confidence: 99%

Particle emissions from laboratory activities involving carbon nanotubes

Tsai

Heitbrink

et al. 2017

J Nanopart Res

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This site study was conducted in a chemical laboratory to evaluate nanomaterial emissions from 20–30 nm diameter bundles of single-walled carbon nanotubes (CNTs) during product development activities. Direct-reading instruments were used to monitor the tasks in real time and airborne particles were collected using various methods to characterize released nanomaterials using electron microscopy and elemental carbon (EC) analyses. CNT clusters and a few high aspect ratio particles were identified as being released from some activities. The EC concentration at the source of probe sonication was found to be higher than other activities including weighing, mixing, centrifugation, coating and cutting. Various sampling methods all indicated different levels of CNTs from the activities, however, the sonication process was found to release the highest amounts of CNTs. It can be cautiously concluded that the task of probe sonication possibly released nanomaterials into the laboratory and posed a risk of surface contamination. Based on these results, the sonication of CNT suspension should be covered or conducted inside a ventilated enclosure with proper filtration or a glovebox to minimize the potential of exposure.

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“…One paper on an international survey regarding occupational health and safety programs, engineering controls and PPE, did not contain data on the concentrations of airborne MNMs particles [13] and could not be used for the calculation of PFs. The remaining 14 papers reported on: enclosure systems (down flow clean rooms with ventilated enclosure hood); ventilation (LEV, enclosure type LEV with proper face velocity, process ventilation, biosafety cabinets); specialized ventilation systems (thermal displacement ventilation); and segregation sources (reactor cabinets) [7][8][9][10][11][12][14][15][16][17][18][19][20][21].…”

Section: Effects Of Enclosure and Ventilationmentioning

confidence: 99%

“…Based on the scores of the risk of bias in Table 2, we excluded 3 papers because of low scores of the risk of bias, in particular the score of RB1 [9,15,20]. The 11 papers reported 27 cases for which we could obtain the PF eng [7, 8, 10-12, 14, 16-19, 21].…”

Section: Effects Of Enclosure and Ventilationmentioning

confidence: 99%

The Effectiveness of Specific Risk Mitigation Techniques Used in the Production and Handling of Manufactured Nanomaterials: A Systematic Review

Myojo

Nagata

Verbeek

2017

J UOEH

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: Many kinds of manufactured nanomaterials (MNMs) have been developed and used as basic materials of industrial products, and they may pose health risks for workers in not only developed countries but also in developing countries. Few studies have looked at the evidence for effects of controls that mitigate the risk of exposure to MNMs. Therefore, we systematically searched the literature from the year 2000 to 2015. We included studies that compared the use of an exposure control to the situation without such a technique and those that measured the exposure to MNMs as the outcome. In order to evaluate the effectiveness of these controls, we used their "protection factor", defined as the ratio between concentrations without and with the control. We located 1,131 references in PubMed and other lists, and out of these references, 41 studies fulfilled our inclusion criteria. We categorized them as engineering controls such as enclosure, local exhaust ventilation or process automation, and as personal protective equipment (PPE). For enclosure systems we found a protection factor beyond 100. For other engineering controls, the better controls scored 10 to 20, but many cases of local exhaust ventilation had a protection factor of less than 10 and some cases even increased exposure. PPE such as N95 or equivalent filtering respirators had a protection factor of approximately 10 tested with nano-sized aerosols. We conclude that there is low quality evidence that specific engineering controls can reduce exposure to MNMs but that enclosure is considerably more effective. For respiratory protection the evidence is of very low quality due to the lack of field studies. This information can be used to decide about controls when exposure to MNMs exceeds proposed occupational exposure limits or when no toxicological information is available for a MNM.

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Effect of carbon nanotubes upon emissions from cutting and sanding carbon fiber-epoxy composites

Cited by 6 publications

References 51 publications

Performance of particulate containment at nanotechnology workplaces

Performance of particulate containment at nanotechnology workplaces

Particle emissions from laboratory activities involving carbon nanotubes

The Effectiveness of Specific Risk Mitigation Techniques Used in the Production and Handling of Manufactured Nanomaterials: A Systematic Review

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