1. © 2008, TSI Incorporated Measurement Methods for Nanoparticles Comparing and Contrasting Measurement Metrics Presented at: National Environmental Partnership Summit May 20, 2008 Tim Johnson TSI Incorporated

2. © 2008, TSI Incorporated 2 Agenda Nanoparticle exposure issues Lung deposition Traditional measurements Nanoparticle measurements Closing remarks Questions, comments and discussion

3. © 2008, TSI Incorporated 3 Nanoparticle Exposure Increasing commercial development Nano-scale materials exhibit startling new properties Occupational health risks are not understood Routes of exposure –Inhalation Most common way for particles to enter the body Lung deposition and health effects –Dermal contact –Ingestion Current research indicates that mass and bulk chemistry may be less important than particle size, surface area, and surface chemistry (or activity) for nanostructured materials (Oberdörster et al. 1992, 1994a,b; Duffin et al. 2002)

4. © 2008, TSI Incorporated 4 Nanoparticle Exposure What experts say If nanoparticles can i.Deposit in the lung and remain there ii.Have active surface chemistry iii.Interact with the body Then, there is the potential for exposure related dosing

5. © 2008, TSI Incorporated 5 Traditional IH Aerosol Measurements No regulations for nanoparticles! Traditional occupational exposure limits based on mass –Size range of ~0.1 – 100 µm OSHA has two size fractions ACGIH, ISO, and CEN define three size fractions Mass based measurement methods –Gravimetric sampling (collecting particles on a filter) –Direct-reading instruments - Photometers

6. © 2008, TSI Incorporated 6 Lung Deposition, Sampling and Modeling Size selective sampling Size fractions and examples Inhalable / total, ≤100 µm > silica Thoracic, ≤10 µm > cotton dust Respirable, ≤4 µm > coal dust Human respiratory tract has 3 regions –Extrathoracic –Tracheobronchial –Alveolar ICRP lung deposition models –Developed in 1966 –Used to develop current standards –Define and characterize lung deposition Most recent work in 1999, by Drs. Phalen / Vincent (ACGIH) to develop a reference worker model –Reference worker lung deposition curves Physiological, activity related, and aerosol parameters

7. © 2008, TSI Incorporated 7 Lung Deposition Diagrammatic representation of respiratory tract regions in humans Based on International Commission of Radiological Protection (1994) and U.S. Environmental Protection Agency (1996a). Air Quality Criteria for Particulate matter, 2004, p 6-5.

8. © 2008, TSI Incorporated 8 Why Monitor Nanoparticles? Quantifying Exposure Quantifying worker exposure Determining effectiveness of ventilation systems Conduct work area monitoring Assist in characterizing, defining, and validating new production processes Selecting and implementing corrective actions Nanoparticle Research & Production Controls Monitor and control particle concentration and size Determine correlation between exposure and health effects

9. © 2008, TSI Incorporated 9 Particle Measurements Nanoparticle General Sampling Practices Look at outdoor concentrations for sources and variability Ventilation system plays a role – Evaluate the effect Background / baseline measurements Mass Measurements - Background Traditional workplace exposure limits are mass based –No regulations currently exist specifically for nanoparticles Mass of one 10 µm particle = 10 6 times the mass of one 100 nm particle = 10 9 times the mass of one 10 nm particle Traditional gravimetric methods are not effective for nanoparticles since toxicity data is based on large particles It takes ~1,000,000,000 (1 billion) 10 nm particles to equal the mass of one 10 µm particle!

10. © 2008, TSI Incorporated 10 Mass Measurements Background Mass can be measured in many ways –Gravimetrically –Photometrically Size selective sampling –PM 10 –PM 2.5 –PM 1.0 –Inhalable, thorasic, respirable

11. © 2008, TSI Incorporated 11 Photometry What is it? Photometers measure particle mass in real time Light-scattering effects vary based on particle properties Photometers come in personal, hand held, table top, and fixed monitor configurations What it does? Typical particle size range: 0.1 to 10 µm Typical concentration range: 0.001 to 100 mg/m 3 Light-scattering technology closely estimates mass concentrations Photometers respond linearly to mass concentration across their range

12. © 2008, TSI Incorporated 12 Photometry Theory of Operation Light- scattering laser photometry is used to determine mass concentration Air sample is drawn into the sensing chamber Laser is used to illuminate the particles Particles scatter light in all directions A lens collects light onto a photo- detector Signal is proportional to the amount of light scattered, which is proportional to the mass concentration of the aerosol in mg/m 3

13. © 2008, TSI Incorporated 13 Gravimetric Mass Measurements Gravimetric Strengths Area and personal samplers in the nano size range Ability to compare to historical gravimetric data Relatively inexpensive –Air sampling equipment –Lab analyses Gravimetric Weaknesses Mass measurements for nanoparticles are difficult due to size and sampling constraints Not a real-time measurement –Takes time to get lab results –Not able to use for point source location, etc. Toxicity for nanoparticles unknown –May not have quantitative relevance as an exposure metric No guidelines or standards for nanoparticles

14. © 2008, TSI Incorporated 14 Photometer Mass Measurements Photometer Strengths Qualitative relevance for agglomerated / aggregated nanoparticles: >100 nm Real-time measurement Field portable, battery operated, and easy to use Personal or area sampling Photometer Weaknesses Not in the size range for discrete nanoparticles: <100 nm Not size resolved Not a compliance method No guidelines or standards for nanoparticles

15. © 2008, TSI Incorporated 15 CPC Number Concentration CPC - what is it? A Condensation Particle Counter (CPC) is an instrument for detecting and counting nanoparticles CPCs do not size particles, only count them CPCs measure number of nanoparticles in real time A CPC uses a method of condensation and growth of particles until they are large enough to be optically detected CPCs require a working fluid (alcohol or water) Typical particle size range: 2.5 nm 1 µm Concentration range: 0 – 500,000 pt/cc

16. © 2008, TSI Incorporated 16 CPC Number Concentration Theory of Operation Particles drawn into instrument Particles pass through a saturator chamber mixing with vapor Air flows through a condenser where vapor condenses onto the particles Particles scatter laser light which is detected by a photo- detector

17. © 2008, TSI Incorporated 17 CPC Number Concentration CPC Strengths CPCs are well suited to measuring nanoparticles in the workplace –Good qualitative measurements –Based on relative changes in concentration Field portable, battery operated, and easy to use –Handheld models relatively inexpensive ~ $5 – 8K CPC Weaknesses CPCs are not a size resolved measurement –Cannot determine original size of particle –Cannot account for agglomeration No guidelines or standards exist for number concentration of nanoparticles –What’s a good number vs. a bad number

18. © 2008, TSI Incorporated 18 Size Distribution Background Why measure size distribution of nanoparticles? –To know the size and number of nanoparticles produced for Exposure information and Quality control purposes –To determine if they are being released from production processes or being re-aerosolized during bulk production use –To determine if nanoparticles are agglomerating or aggregating after production Size distribution can be measured in a number of ways –Scanning Mobility Particle Sizer (SMPS), <1 µm –Optical Particle Counter (OPC), >0.3 µm

19. © 2008, TSI Incorporated 19 SMPS Size Technology What is it? A SMPS uses a Differential Mobility Analyzer (DMA) and a CPC to measure size and number concentration of nanoparticles What it does? DMA separates particles according to charge and electrical mobility for size classification CPC grows the particles to a detectible size for counting Has high resolution (64 channels/decade) and high size accuracy Wide size range (2.5 – 1000 nm) Wide concentration range (up to 10 8 particles/cm 3 )

20. © 2008, TSI Incorporated 20 SMPS Technology Theory of Operation Particles go through a inlet conditioner and a neutralizer Creating a known charge distribution on the particles Particles pass thru DMA Particles are separated and classified according to electrical mobility size Classified particles counted by a CPC Particles are grown and counted in the CPC Size distribution is determined

21. © 2008, TSI Incorporated 21 SMPS Size Distribution SMPS Strengths Nanoparticle size range Real-time measurement –Size distribution determined in several minutes Size resolved, quantitative measurement –For process applications –Determine if agglomerating Qualitative area sampling SMPS Weaknesses No guidelines or standards for nanoparticles Limited field portability Computer controlled –Not your typical IH instrument

22. © 2008, TSI Incorporated 22 OPC Technology What is it? A OPC measures the size and number concentration of particles, > 0.3  m OPCs come in hand held, table top and fixed monitor configurations What it does? OPCs measure particle size and number concentration by detecting light scattered from individual particles in real-time OPCs may be able to measure nanoparticles in the workplace –Nanoparticles must have agglomerated/aggregated >0.3 µm in size OPCs typically have multiple size fraction bins OPC size bins can be arranged to simultaneously measure size fractions Typical particle size range: 0.3 to 15  m Typical concentration range: 2x10 6 particles/ft 3 (70 pt/cc)

23. © 2008, TSI Incorporated 23 OPC Technology Theory of Operation Single particles are drawn through a focused laser sheath and the resulting scattered light is collected by a mirror and focused on to a photo-detector Concentration is derived from the count rate and particle size is derived from the pulse heights Electronics have to be very fast to be able to count and distinguish particle sizes

24. © 2008, TSI Incorporated 24 OPC Size Distribution OPC Strengths For agglomerated/aggregated nanoparticles >300 nm Size resolved measurement Real-time measurement Qualitative area sampling –Relative changes in number concentration –Locate point sources –Select and validate engineering controls Field portable, battery operated, and easy to use OPC Weaknesses Not in the size range for discrete nanoparticles, <0.3 µm No guidelines or standards for nanoparticles Limited to low concentration

25. © 2008, TSI Incorporated 25 Surface Area Measurements Background Nanoparticles vs. large particles –Has relatively little mass, large surface area and large numbers Nanoparticle exposure studies –Drs. Driscoll (1996) and Oberdörster (2001) have shown that surface area (μm 2 /cc) plays an important role in the toxicity of nanoparticles Surface area is the metric that initial evidence shows correlates well with particle-induced adverse health effects Potential for adverse health effects is proportional to particle surface area (Driscoll, 1996; Oberdörster, 2001) Emerging need to assess workplace exposure to nanoparticles based on surface area

26. © 2008, TSI Incorporated 26 Lung Deposition Diagrammatic representation of respiratory tract regions in humans Based on International Commission of Radiological Protection (1994) and U.S. Environmental Protection Agency (1996a). Air Quality Criteria for Particulate matter, 2004, p 6-5. Lung Deposition – revisited Inhalation is primary exposure route The respiratory tract consists of 3 major regions –Extrathoracic region: uppermost region –Tracheobronchial (TB) region: middle region –Alveolar (A) region: innermost region Uptake of inhaled particles according to deposition in respiratory tract

27. © 2008, TSI Incorporated 27 What it does? A diffusion charger measures the charge of the particles. This charge calibrated to the surface area deposited in the TB or A regions of the lung –Does not measure the total surface area of particles sampled, only the TB or A deposition fractions The ion trap voltages are optimized to correspond to the TB or A lung deposition curves for the reference worker Particle size range: 10 – 1000 nm Concentration range: TB = 1 – 2,500 µm/cc A = 1 – 10,000 µm/cc User-selectable measurement response (TB or A) Diffusion Charger Technology

28. © 2008, TSI Incorporated 28 Diffusion Charger Technology Based on diffusion charging of sampled particles followed by detection using an electrometer Theory of Operation Clean air is ionized Diffusion Charging –Ions and aerosol sample streams are turbulently mixed and the particles are charged Ion Trap –Excess ions are removed –Acts as an inlet conditioner or a size-selective sampler –Ion trap voltage can be changed between TB and A response

29. © 2008, TSI Incorporated 29 Diffusion Charger Technology Theory of Operation (cont.) Electrometer –Particles pass through the electrometer –Particles collected on a conductive filter –Amplifies and measures the charge on the surface of the particles –Measured charge converted into deposited surface area in units of µm 2 /cc

30. © 2008, TSI Incorporated 30 Diffusion Charger Technology Diffusion Charger Strengths Research shown that surface area is highly correlated with observed toxic effects Wide size range, 10- 1000 nm Real time measurement Qualitative area sampling –Data correlates well with CPC and SMPS measurement trends Diffusion Charger Weaknesses Not size resolved –Cannot determine original size of particle –Cannot account for agglomeration No guidelines or standards for nanoparticles –What’s a good number vs. a bad number

31. © 2008, TSI Incorporated 31 0.0010.010.1110100 Particle Size Range (micrometers ) Inhalable (Total dust) TSP Respirable Thoracic Particle Size Range for Aerosol Instruments Photometer CPC-alcohol OPC Diffusion Charger 4 OPC: Optical Particle Counter CPC: Condensation Particle Counter SMPS: Scanning Mobility Particle Sizer CPC - Water SMPS

32. © 2008, TSI Incorporated 32 Application Comparison 1 Engineered nano particles of homogenous material less than 0.1 micron (100 nm) in diameter. 2 Agglomerated and aggregated nano particles greater than 0.1 microns (100 nm) diameter for photometers and greater than 0.3 microns (300nm) for OPC’s. 3 The Health effects of engineered nano particles and ultrafine particles below 0.1 micron (100 nm) in diameter are not completely understood. Research suggests these ultrafine particles may cause the greatest harm. There are currently no established exposure limits or governmental regulations specifically addressing ultrafine or nano particles exposure. N/AExcellent PoorClean Room Monitoring N/AExcellent Filter Testing N/AExcellentPoorExcellent Respirator Fit Testing ExcellentGoodPoorExcellentEmissions Monitoring Excellent 3 Good Outdoor Environmental Monitoring Excellent 3 Poor 1/ Good 2 Industrial Workplace Monitoring (Nano-Materials) N/A PoorExcellentIndustrial Workplace Monitoring (Conventional) N/AExcellentN/APoorIndoor Air Quality - Ultrafine Particle Tracking N/A Good Indoor Air Quality - Conventional Studies Diffusion charger CPCOPCPhotometer

33. © 2008, TSI Incorporated 33 PhotometerOPCCPCSMPSDiffusion Charger Typical Size Range0.1 to 10 um0.3 to 20 µm 0.0025 to 3.0 µm 0.0025 to 1 µm 0.02 to 0.1 um Measures Particle Mass (estimate)YesNo Typical Mass Concentration Range0.01 to 100 mg/m 3 N/A Measures Particle SizeNoYesNoYesNo Detects Single ParticlesNoYes No Typical Number Concentration Range (Particles / cc) N/A2 x 10 6 1.5 x 10 10 1 x 10 8 N/A Upper Limit, number concentration (particles/cc) N/A70500,0001 x 10 8 N/A Measures Lung-Deposited Surface Area No No 1 Yes OPC = Optical Particle Counter CPC = Condensation Particle Counter SMPS = Scanning Mobility Particle Sizer 1 Surface area can be calculated using SPMS size distribution data. Aerosol Technology Comparisons

34. © 2008, TSI Incorporated 34 Research Work References 1.Donaldson, K. et al. Ultrafine (Nanometer) Particle Mediated Lung Injury, J. Aerosol Sci. 29(5/6):553-560. (1998) 2.Driscoll K.E. Role of inflammation in the development of rat lung tumors in response to chronic particle exposure. Inhal. Toxicol. 8 [suppl1: 85-98] (1996) 3.Driscoll K.E. et al. Pulmonary inflammatory, chemokine, and mutagenic responses in rats after subchronic inhalation of carbon-black. Toxicol. Appl. Pharmacol. 136, 372-380 (1996) 4.Driscoll K.E. et al. Characterizing mutagenesis in the hprt gene of rat alveolar epithelial- cells. Exp. Lung Res. 21, 941-956 (1995). 5.Heinrich et al. Chronic inhalation exposure of Wistar rats and two different strains of mice to diesel engine exhaust, carbon black, and titanium dioxide. Inhal. Toxicol. 7: 533- 556 (1995) 6.Lam C.W. et al. Pulmonary toxicity of single-wall carbon nanotubes in mice 7 and 90 days after intratracheal instillation, Toxicol. Sci. 77 (1): 126-134 (2004)Pulmonary toxicity of single-wall carbon nanotubes in mice 7 and 90 days after intratracheal instillation 7.Lee K.P. et al. Pulmonary response of rats exposed to titanium dioxide by inhalation for two years. Toxicol. Appl. Pharmacol. 79: 179-192 (1985) 8.Li N. et al. Ultrafine particulate pollutants induce oxidative stress and mitochondrial damage, Environ. Health Persp. 111:455-460 (2003) 9.Nemmar A. et al. Passage of inhaled particles into the blood circulation in humans, Circulation 105:411-414 (2002)

35. © 2008, TSI Incorporated 35 Research Work References 10.Number A. et al. Passage of intratracheally instilled ultrafine particles from the lung into the systemic circulation in hamster. Am J Respir Crit Care Med (164) 1665-1668 (2001) 11. Oberdörster E. Manufactured nanomaterials (Fullerenes, C-60) induce oxidative stress in the brain of juvenile largemouth bass, Environ. Health Persp. 112 (10): 1058-1062 (2004)Manufactured nanomaterials (Fullerenes, C-60) induce oxidative stress in the brain of juvenile largemouth bass 12. Oberdörster G. Pulmonary effects of inhaled ultrafine particles. Int. Arch. Occup. Environ. Health 74:1-8 (2001) 13. Oberdörster, G. Significance of Particle Parameters in the Evaluation of Exposure-Dose- Response Relationships of Inhaled Particles, Particulate Sci. Technol. 14(2):135-151 (1996). 14. Oberdörster G. et al Association of particulate air pollution and acute mortality: involvement of ultrafine particles? Inhal. Toxicol. 7:111-124 (1995) 15. Penttinen P. et al. Number concentration and size of particles in urban air: effects on spirometric lung function in adult asthmatic subjects, Environ. Health Persp. 109:319-323 (2001) 16. Shanbhag, A. S. et al. Macrophage/Particle Interactions: Effect of Size, Composition and Surface Area, J. Biomed. Mat. Res. 28(1):81-90 (1994). 17. Utell M.J. et al. Acute health effects of ambient air pollution: the ultrafine particle hypothesis. J. Aerosol Med. 13:355-359 (2000). 18. Warheit D. B. et al. Comparative Pulmonary Toxicity Assessment of Single-wall Carbon Nanotubes in Rats, Toxicol. Sci. 77 (1): 117-125 (2004)

36. © 2008, TSI Incorporated 36 Closing Remarks Nanoparticle exposure is an issue of concern Traditional measurements were discussed Metrics for nanoparticle measurements were discussed along with available instruments Applications of nanoparticle measurements Review of bibliography of health effects studies