Nano exposure monitoring

UT-BattelleDepartment of Energy

Exposure MonitoringTechniques for Nanomaterials

American Chemical Society MeetingAugust 30, 2011

Joseph M. Pickel, Ph.D. CHO

Center for Nanophase Materials Sciences

Oak Ridge National Laboratory

2 UT-BattelleDepartment of Energy

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)


Challenge and General Strategy for Nanomaterial Safety in the Laboratory

Review of Current Approaches

Discussion of New Developments

Outline


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

quantitation

Challenge


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 science


As in any hazardous exposure to chemicals, a good health and safety management approach should include these four elements:

1.Identify the hazard

2.Asses the risk

3.Prevent or control therisk

4.Evaluate the effectiveness of controlmeasures

Asses the risk

Evaluate the effectiveness

Identify the hazard

Prevent or control the risk

Control of Nanoparticles


Starting Point: Identify/ Assess SituationLack of and/or uncertainty of data warrants that Nanomaterials must handled using the precautionary principle:

“toxic in the short run and chronically toxic in the long run”

Photos courtesy RJ LEE Group


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 Exposure


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 operational

guidelines

Evaluate Effectiveness of ControlsSampling and Exposure Monitoring


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?)

Challenge


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


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 technologies


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.

Nanotechnology Safety Approach


Install similar engineering controls used to control gases and vapors:

EnclosuresLocal exhaust ventilationFume hoods

Use of HEPA Filtration

Limitation on number of workers and exclusion of others

Use of suitable personal protective equipment

Good Chemical Hygiene (Prohibition of eating and drinking in contaminated areas, Regular cleaning of walls and other surfaces)

Controls to limit exposure


Tools for Evaluating Nanomaterial Exposures

Surface area – diffusion charger

Scanning Mobility Particle Sizer (SMPS)

Count– CPC(TSI), scanning mobility, GRIMM

Composition/Chemistry - GC-MS

Filter/Impinger/Impactor-TEM/SEM


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 liter


Sampling Approach for CNMS Activities

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)


Working in fume hood

Grinding the barium fluoride inside the hood.

CPC monitoring begins in room F263.

Crushed powder was shook from the filter paper into a glass holder.

At 10:09 a.m. to end of log, baseline of inside the 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 540Hood background 1481-1887 1665.16 78.83 145


Worker and Environmental Assessment of Potential Unbound Engineered Nanoparticle Releases– Multiphase study (Assessment and Control Band

Development)– Conducted by LBNL and RJLEE group

Berkeley Study


Protocol used to survey efficacy of control methods

Results motivated change to administrative protocols

Evaluation of Spray System at CNMS


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 / enclosures


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 assumptions


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-response


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 later


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 mass


Surface area as dominant characteristic contributing to toxicity is plausible


Nanoparticle Surface Area is Huge!

• 1/2 the size = 2x the surface area and 23 = 8x the number or particles

• Approaches 100% of atoms on the surface

•www.gly.uga.edu/railsback/1121WeatheringArea.jpeg

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64 512


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 toxicity


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 studies


Worker Health can be protected– Prudent practices– ALARA/ALARP Principles– Control Banding

Emerging information is solidifying technical basis for exposure assessment– Toxicological data– OELS– Sampling methodology,

techniques and tools…– But there is no “right answer” yet

Summary and ConclusionsAsbestos Fiber

Welding Fumes


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 www.asse.org

Nanotechnology research resources– National Institute for Occupational Safety and Health (NIOSH)– National Nanotechnology Initiative (NNI)– Rice University's International Council on Nanotechnology

(ICON) – Nanoparticle Information Library (NIL)


Nano exposure monitoring

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