Nano exposure monitoring


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Presented at the 2011 ACS National Fall Meeting in Denver, Colordao

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Nano exposure monitoring

  1. 1. Exposure Monitoring Techniques for Nanomaterials American Chemical Society Meeting August 30, 2011 Joseph M. Pickel, Ph.D. CHO Center for Nanophase Materials Sciences Oak Ridge National LaboratoryUT-BattelleDepartment of Energy
  2. 2. Acknowledgements Scott Hollenbeck, CIH (ORNL-CNMS) John Jankovich, CIH (ORNL- Ret) Burt Ogle, Ph.D., CIH (Western Carolina) Tracy Zontek, Ph.D., CIH (Western Carolina) Randy Ogle, CIH (ORNL-Ret, RJLee Group) Gary Casuccio (RJLee Group) Michaela Hall, MPH (ORNL) Samantha Connell (Alabama, Birmingham)2 UT-Battelle Department of Energy
  3. 3. Outline Challenge and General Strategy for Nanomaterial Safety in the Laboratory Review of Current Approaches Discussion of New Developments3 UT-Battelle Department of Energy
  4. 4. Challenge Ensure that we are protecting workers – From materials that vary in size, shape, and composition – Having unknown toxicity and reactivity – By measuring a number of properties (count, surface area, mass) – Using tools, sometimes at or near their limits of quantitation4 UT-Battelle Department of Energy
  5. 5. Nanoscale Materials Properties  Relatively little mass – Mass of 1 billion 10 nm particles = mass of 10 µm particle  Large surface area  Produced in large numbers  Quantum effects – Change their physical, chemical, and biological properties  Behave like gases – Stay suspended for weeks  Disperse quickly  Tend to agglomerate quickly after production – Good for health effects – Bad for science5 UT-Battelle Department of Energy
  6. 6. Control of Nanoparticles As in any hazardous exposure to chemicals, a good health and safety management approach should include these four Identify the hazard Asses the risk elements: 1.Identify the hazard 2.Asses the risk 3.Prevent or control the risk Evaluate the effectiveness Prevent or control the risk 4.Evaluate the effectiveness of control measures6 UT-Battelle Department of Energy
  7. 7. Starting Point: Identify/ Assess SituationLack of and/or uncertainty of data warrants thatNanomaterials must handled using the precautionaryprinciple:“toxic in the short run and chronically toxic in the long run” Photos courtesy RJ LEE Group7 UT-Battelle Department of Energy
  8. 8. Prevent/Control Risk - Assumptions- Traditional Controls Work - Engineering - Administrative - Personal Protection- Material Releases Can be Measured- Hazard and associated Risk are product of Toxicity and Exposure8 UT-Battelle Department of Energy
  9. 9. Evaluate Effectiveness of Controls Sampling and Exposure Monitoring To check for releases (process control) – Leak checks on containment – Effectiveness of capturing system To define ambient concentration – Establish need for exposure control  Exceedance of regulated concentration  Exceedance of operational9 UT-Battelle guidelines Department of Energy
  10. 10. Challenge Ensure that we are protecting workers – From materials that vary in size, shape, and composition (what are we looking for?) – Having unknown toxicity and reactivity (how much is okay?) – By measuring a number of properties (count, surface area, mass) (which is most important) – Using tools, sometimes at or near their limits of quantitation (how many tools are enough?)10 UT-Battelle Department of Energy
  11. 11. Current Guidance on Nanomaterial Safety NIOSH: Approaches to Safe Nanotechnology DOE Nanoscience Research Centers: Approach to Nanomaterial ES&H (Rev 3a, 5/08) ISO/TR 12885:2008, Health and safety practices in occupational settings relevant to nanotechnologies ASTM E2535 - 07 Standard Guide for Handling Unbound Engineered Nanoscale Particles in Occupational Settings11 UT-Battelle Department of Energy
  12. 12. Foundation of NSRC Approach…  Integrated Safety Management followed from inception  Designed to accommodate the planned R&D  ESH and projected R&D staff designed individual labs and controls  Used experience, benchmarking, and best available control technologies12 UT-Battelle Department of Energy
  13. 13. Nanotechnology Safety Approach  Sound Workplace Practice – SOGs/SOPs  Effective workplace controls: engineering, administrative, and PPE where appropriate (i.e. protect routes of entry, particularly inhalation and dermal exposures).  Safety and Health Training – disseminating appropriate hazard information  Safe procedures for handling and disposal of hazardous (and potentially hazardous) materials.13 UT-Battelle Department of Energy
  14. 14. Controls to limit exposureInstall similar engineering controlsused to control gases and vapors: Enclosures Local exhaust ventilation Fume hoodsUse of HEPA FiltrationLimitation on number of workers andexclusion of othersUse of suitable personal protectiveequipmentGood Chemical Hygiene (Prohibition ofeating and drinking in contaminatedareas, Regular cleaning of walls andother surfaces)14 UT-Battelle Department of Energy
  15. 15. Tools for Evaluating NanomaterialExposures Surface area – diffusion charger Scanning Mobility Particle Sizer (SMPS) Count– CPC(TSI), scanning mobility, GRIMM Composition/Chemistry - GC-MS Filter/Impinger/Impactor-TEM/SEM15 UT-Battelle Department of Energy
  16. 16. Sampling Strategy Determine if nanomaterials are controlled at the source – Use of Condensation Particle Counter, TSI 3007  Range from 0.01 - >1 um with a concentration range of 0 to 100,000 particles/cc – SMPS (Sequential Mobility Particle Sizer)  Combination of electrostatic classifier and condensation particle counter  Determines particle sizes and distributions – GRIMM Aerosol Spectrometer  Particle sizes in 13 channels ranging from greater than 0.3 um to greater than 10 um, with a count range from 1 to 2 million counts per liter16 UT-Battelle Department of Energy
  17. 17. Sampling Approach for CNMSActivities TSI 3007 CPC, particle counts to 10nm Nucleopore filter + SEM/TEM – size, – shape, – metallic composition Baseline index of “clean” watch for other sources (air pollution, combustion) Direct count, estimated mass, and surface area for each process Passive monitoring (TEM/SEM Stub or grid)17 UT-Battelle Department of Energy
  18. 18. Working in fume hood Activity / Materials Range (p/cc) Mean (p/cc) SD Time (s) Room background 970-1344 1214.19 50.58 426 Grinding in hood 1161-1929 1580.73 164.38 540 Hood background 1481-1887 1665.16 78.83 145 At 10:09 a.m. to end of log, baseline of inside Grinding the barium the hood. fluoride inside the hood. Crushed powder was shook from the filter paper into a glass holder. CPC monitoring begins in room F263.18 UT-Battelle Department of Energy
  19. 19. Berkeley Study Worker and Environmental Assessment of Potential Unbound Engineered Nanoparticle Releases – Multiphase study (Assessment and Control Band Development) – Conducted by LBNL and RJLEE group19 UT-Battelle Department of Energy
  20. 20. Evaluation of Spray System at CNMS Protocol used to survey efficacy of control methods Results motivated change to administrative protocols20 UT-Battelle Department of Energy
  21. 21. General Results of Sampling Protocol  CPC – Extremely effective to identify background levels and spikes – Background levels crucial to data interpretation – Not effective to collect employee exposure samples  GRIMM Aerosol Spectrometer – Provides particle size distribution – Did not measure particles less than 300 nm  Particle spikes found due to equipment: – HEPA vacuum – Heat exchanger on laser enclosure  Controls and work practices were effective overall: – Work in hoods (HEPA) – Wet methods – Closed systems / enclosures21 UT-Battelle Department of Energy
  22. 22. Discussion of Protocol - Focus on research / laboratory environments (non- production) - Emphasis on CPC and Microscopy as convenient, universally accessible tools - Combination approach allows confirmation of source - Protocol measures particle count, distribution and composition - Forgo gravimetric measurements due to technical concerns - Forthcoming revision of protocol removes GRIMM - Continuous Improvements to method via research – on new equipment and components – Sampling methods and assumptions22 UT-Battelle Department of Energy
  23. 23. Exposure limits for Nanomaterials No current regulatory limits ALARA in R&D (Prudent Practice) Current guidance (and tox data) based on mass (e.g., LD50 mg/Kg) Older standards based on particle counts Not yet a foundation for a surface area based dose-response23 UT-Battelle Department of Energy
  24. 24. Other Considerations – Emerging Toxicity Information  Depends on chemistry, morphology, surface charges, etc.  Probably relates to particle surface area especially for insoluble/low soluble  Free radicals (in vitro)  Increased inflammatory response (in vivo)  Translocation to target organs (rodents)  Allergic asthma like symptoms  Aggravate symptoms of pneumonia  Cardiac effect-2 days later24 UT-Battelle Department of Energy
  25. 25. NIOSH on Titanium Dioxide  Exposure limit of 1.5 milligrams per cubic meter for fine TiO2 (particles greater than 0.1 micrometers in diameter)  0.1 mg/m3 for ultrafine particles as time-weighted averages for up to 10 hours per day during a 40-hour work week  Suggests that ultrafine TiO2 particles may be more potent than fine TiO2 particles at the same mass. This may be due to the fact that the ultrafine particles have a greater surface area than the fine particles at the same mass25 UT-Battelle Department of Energy
  26. 26. Surface area as dominant characteristic  contributing to toxicity is plausible26 UT-Battelle Department of Energy
  27. 27. Nanoparticle Surface Area is Huge! 8 1 • 1/2 the size = 2x  the surface area  and 23 = 8x the  number or  particles • Approaches 100%  of atoms on the  surface 64 512 • UT-Battelle Department of Energy
  28. 28. Discussion on Exposure Guidelines  Current progress is towards mass based limits – NIOSH proposes mass based Recommended Exposure Limit  Basis approximates limits of quantitation rather than toxicological considerations  Forthcoming article to propose 530 p/cc (53000p/cc for respirator) for non-doped carbon based aerosols – Extrapolated particle based guideline – Applicable to poorly soluble, low toxicity28 UT-Battelle Department of Energy
  29. 29. Summary and Conclusions All processes should be carefully evaluated and prudent controls in place prior to start – Control banding Air monitoring can evaluate release of nanoscale materials in workplace – Determine effectiveness of controls Poor work practices can lead to potential contamination Follow standard IH practices focusing on evaluation and control Consider end results and future – Characterize materials – Ensure health and safety – Data for epidemiological studies29 UT-Battelle Department of Energy
  30. 30. Summary and Conclusions Worker Health can be Asbestos Fiber protected – Prudent practices – ALARA/ALARP Principles – Control Banding Emerging information is Welding Fumes solidifying technical basis for exposure assessment – Toxicological data – OELS – Sampling methodology, techniques and tools… – But there is no “right answer” yet30 UT-Battelle Department of Energy
  31. 31. References and Resources Jankovic, J T; Hollenbeck, S M; “Ambient Air Sampling During Quantum-dot Spray Deposition” International Journal of Occupational and Environmental Health 2010 ,16:4, 388-398. Jankovic, J.T; Ogle, B.R.; Zontek, T.L.; Hollenbeck, S.M. “Characterizing Aerosolized Particulate As Part Of A Nanoprocess Exposure Assessment” International Journal of Occupational and Environmental Health 16:4, 451-457 Jankovic, J.T; Ogle, B.R.; Zontek, T.L.; Hall, M. A.; Hollenbeck, S.M. “Particle Loss in a Scanning Mobility Particle Analyzer Sampling Extension Tube” International Journal of Occupational and Environmental Health; 16:4, 429-433. Zontek, T. L. ; Ogle, B.R.; Ogle, R.B “Evaluating an air monitoring technique” Professional Safety 2010 34 Nanotechnology research resources – National Institute for Occupational Safety and Health (NIOSH) – National Nanotechnology Initiative (NNI) – Rice Universitys International Council on Nanotechnology (ICON) – Nanoparticle Information Library (NIL)31 UT-Battelle Department of Energy
  32. 32. 32 UT-Battelle Department of Energy