Applying NIOSH’s Nanomaterial Sampling Methods in the Laboratory Setting – Preliminary Observations<br />Michael K. Blumer...
Presentation Outline <br />Review Occupational Exposure Monitoring<br />Review NIOSH Sampling Methods & Limitations<br />C...
Disclaimers<br />Certain commercial instruments are identified in this paper in order to specify the sampling procedures a...
Introduction<br />NIST Safety Office is evaluating exposures in working labs<br />NIST researchers fabricate, test, and us...
Occupational Exposure Monitoring<br />Traditional Exposure Monitoring<br />Occupational Exposure Limit (OEL)<br />Airborne...
ENM Exposure Monitoring<br />No OELs in most cases<br />Instead, evaluate change over background(Standard philosophy is to...
NIOSH NEAT Sampling Protocol<br />Particle Counters - Hand-held direct-reading<br />Condensation Particle Counter (CPC)<br...
Condensation Particle Counter<br />Saturated alcohol condenses on particles to grow them to 10 micrometers (µm)<br />Count...
Optical Particle Counter<br />Counts particles based on laser light scattering<br />Six size channels: 300 nm – 10,000 nm...
Filter Sampling<br />Carbon Nanotubes<br />NIOSH Method 5040, Diesel Particulate Matter (as Elemental Carbon)<br />Thermal...
Case Study: Spraying Carbon Nanotubes<br />All work performed in fume hood, HEPA filtered exhaust to outside<br />Weigh d...
Work Location<br />12<br />
Spraying MWCNTs<br />13<br />
Filter Sampling<br />Three pairs of filters<br />Researcher’s personal breathing zone<br />Stationary samples at face of f...
Personal Samples<br />15<br />
Particle Counters<br />CPC logs data every 1 minute<br />OPC logs data every 30 seconds, 1-sec. delay<br />Background leve...
Filter Sampling Results<br />17<br />
Particle Counter Results<br />Three sets of data<br />Smallest size channel on OPC (0.3 µm – 0.5 µm)<br />Five larger OPC ...
Effect of Background Particulate Levels<br />19<br />
Comparison of Work and Background Particulate Concentrations (Geometric means)<br />OPC Small Size Channel<br />OPC Large ...
Optical Particle Counter MeasurementsSmall- and Large-Size Channels (one scale)<br />21<br />
Optical Particle Counter MeasurementsSmall- & Large-Size Channels (two scales)<br />22<br />
23<br />
Conclusions<br />Researcher was not exposed to measureable levels of airborne MWCNTs during spraying<br />Local exhaust ve...
Questions?<br />michael.blumer@nist.gov<br />Photo: A 40-nanometer-wide NIST logo made with cobalt atoms on a copper surf...
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Nanomaterial sampling at NIST

Sampling protocols used to determine employee exposure to nanoparticles at NIST
Published on: Mar 3, 2016
Published in: Technology      Business      
Source: www.slideshare.net


Transcripts - Nanomaterial sampling at NIST

  • 1. Applying NIOSH’s Nanomaterial Sampling Methods in the Laboratory Setting – Preliminary Observations<br />Michael K. Blumer, CIH<br />Jason T. Capriotti, CIH, CSP<br />National Institute of Standards and Technology (NIST)<br />Office of Safety, Health and Environment (OSHE)<br />
  • 2. Presentation Outline <br />Review Occupational Exposure Monitoring<br />Review NIOSH Sampling Methods & Limitations<br />Case Study: Spraying Multi-walled Carbon Nanotubes<br />Photo: Carbon nanotubes with impurities; Credit: NIST<br />2<br />
  • 3. Disclaimers<br />Certain commercial instruments are identified in this paper in order to specify the sampling procedures adequately. Such identification is not intended to imply recommendation or endorsement by the National Institute of Standards and Technology, nor is it intended to imply that the equipment identified is necessarily the best for the purpose.<br />Due to the preliminary nature of the sampling activities, no attempt at deriving statistical inferences was made.<br />3<br />
  • 4. Introduction<br />NIST Safety Office is evaluating exposures in working labs<br />NIST researchers fabricate, test, and use variety of nanomaterials<br />Laboratory Setting<br />Small amounts of many different materials<br />Short-duration activities<br />Small population of highly educated, specialized workers<br />Exposure controls are commonly present<br />Local exhaust ventilation; fume hood, etc.<br />Personal protective equipment; lab coats, gloves, glasses<br />Ref: NIST HSI #23<br />Photo: Assembly of polystyrene particles held together by polyelectrolyte interaction fabricated by the Complex Fluids Group; Credit: NIST<br />4<br />
  • 5. Occupational Exposure Monitoring<br />Traditional Exposure Monitoring<br />Occupational Exposure Limit (OEL)<br />Airborne concentration – mass of contaminant<br />Set by governmental agency or scientific association<br />Based on medical case studies, toxicology, epidemiology<br />Collect physical sample of airborne contaminant with pump and filter or adsorption tube<br />Laboratory analysis to quantify material collected<br />Calculate concentration and compare with OEL<br />5<br />
  • 6. ENM Exposure Monitoring<br />No OELs in most cases<br />Instead, evaluate change over background(Standard philosophy is to control exposure to carcinogens as low as technically possible)<br />Chemical-specific OELs for Carbon Nanotubes and Nanowires and Titanium Dioxide<br />Methods sensitive enough to reach lower OEL<br />NIOSH sampling methods for ENMs<br />6<br />
  • 7. NIOSH NEAT Sampling Protocol<br />Particle Counters - Hand-held direct-reading<br />Condensation Particle Counter (CPC)<br />Optical Particle Counter (OPC)<br />Together provide semi-quantitative estimate of nanoparticles<br />Filter sample for SEM/TEM analysis<br />Particle identification and morphology<br />Filter sample for airborne chemical mass concentration<br />Traditional NIOSH sampling & analytical methods<br />Filter pairs at nanoparticle source and researcher’s personal breathing zone (PBZ)<br />Ref: Methner, M. , Hodson, L. and Geraci, C. (2010) 'Nanoparticle Emission Assessment Technique (NEAT) for the Identification and Measurement of Potential Inhalation Exposure to Engineered Nanomaterials — Part A', Journal of Occupational and Environmental Hygiene, 7: 3, 127 — 132, First published on: 16 December 2009 (iFirst)<br />7<br />
  • 8. Condensation Particle Counter<br />Saturated alcohol condenses on particles to grow them to 10 micrometers (µm)<br />Count with optical detector<br />10 nm – 1,000 nm particle size<br />1 – 100,000 (particles/cm3)<br />Concentration accuracy ± 20 %<br />8<br />
  • 9. Optical Particle Counter<br />Counts particles based on laser light scattering<br />Six size channels: 300 nm – 10,000 nm<br />Smallest size channel = 300 nm – 500 nm<br />Limited data-logging memory<br />Counting efficiency 50 % @ 300 nm,100 % @ >450 nm<br />Results in particles/liter of air<br />9<br />
  • 10. Filter Sampling<br />Carbon Nanotubes<br />NIOSH Method 5040, Diesel Particulate Matter (as Elemental Carbon)<br />Thermal-optical analysis, flame ionization detector<br />Estimated LoD: 0.3 µg per filter portion<br />Precision: 0.19 @ 1 µg Carbon, 0.01 @ 10 – 72 µg Carbon<br />SEM/TEM Analysis<br />Filter selection: Analyst’s preference or NIOSH Method 7402, Asbestos by TEM<br />Bulk sample to assist analyst in ENM identification<br />Difficult with under- or over-loaded filter<br />Ref: National Institute for Occupational Safety and Health (NIOSH):Methods 5040 and 7402. In NIOSH Manual of Analytical Methods(NMAM), 4th ed. DHHS (NIOSH) Pub. No. 94-113. P.C. SchlechtandP.F. O’Conner (eds.) Cincinnati, Ohio: U.S. Department of Health andHuman Services, Centers for Disease Control and Prevention, NIOSH,<br />1994.<br />10<br />
  • 11. Case Study: Spraying Carbon Nanotubes<br />All work performed in fume hood, HEPA filtered exhaust to outside<br />Weigh dry powder<br />Add 20 ml water and surfactant<br />Sonicate solution inside enclosure and in open-top aqua sonicator<br />Spray liquid solution of MWCNTs by use of air brush<br />Apply “canned” compressed air to speed drying<br />Two rounds of spraying totaling 30 minutes<br />11<br />
  • 12. Work Location<br />12<br />
  • 13. Spraying MWCNTs<br />13<br />
  • 14. Filter Sampling<br />Three pairs of filters<br />Researcher’s personal breathing zone<br />Stationary samples at face of fume hood<br />Inside fume hood, next to target<br />Pump flow of 3.5 lpm for 82 minutes provides limit of quantification below REL for carbon nanotubes<br />14<br />
  • 15. Personal Samples<br />15<br />
  • 16. Particle Counters<br />CPC logs data every 1 minute<br />OPC logs data every 30 seconds, 1-sec. delay<br />Background levels before and after ENM handling<br />Hand-held from point of operation to PBZusually at face of hood<br />16<br />
  • 17. Filter Sampling Results<br />17<br />
  • 18. Particle Counter Results<br />Three sets of data<br />Smallest size channel on OPC (0.3 µm – 0.5 µm)<br />Five larger OPC size channels combined (0.5 µm – >5 µm)<br />CPC data (0.1 µm –>1 µm)<br />Four stages of work<br />Background<br />Two rounds of prep combined<br />Two rounds of spraying combined<br />Cleanup<br />Compare geometric means, work / background<br />18<br />
  • 19. Effect of Background Particulate Levels<br />19<br />
  • 20. Comparison of Work and Background Particulate Concentrations (Geometric means)<br />OPC Small Size Channel<br />OPC Large Size Channels<br />CPC<br />20<br />
  • 21. Optical Particle Counter MeasurementsSmall- and Large-Size Channels (one scale)<br />21<br />
  • 22. Optical Particle Counter MeasurementsSmall- & Large-Size Channels (two scales)<br />22<br />
  • 23. 23<br />
  • 24. Conclusions<br />Researcher was not exposed to measureable levels of airborne MWCNTs during spraying<br />Local exhaust ventilation with HEPA filtration is effective at controlling nanoparticles<br />Limitations of particle counters significantly hamper identification of nanoparticles<br />Difficult to identify ENMs over normal background<br />Can improve sensitivity by activelylowering background particleconcentration<br /> - Do not need to HEPA filter incoming air<br />Photo: Nanowires that emit UV lightCredit: Lorelle Mansfield/NIST<br />24<br />
  • 25. Questions?<br />michael.blumer@nist.gov<br />Photo: A 40-nanometer-wide NIST logo made with cobalt atoms on a copper surface. The ripples in the background are made by electrons, which create a fluid-like layer at the copper surface. Each atom on the surface acts like a pebble dropped in a pond. Credit: J. Stroscio, R. Celotta/NIST<br />25<br />

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