Considerations for Selecting Standard Materials for Occupational Safety and Health

Vladimir Murashov, Ph.D.Special Assistant to the Director

National Institute for Occupational Safety and Health

Interagency Workshop on Standards for

EHS Research Needs for Engineered Nanoscale Materials September 12-14, 2007

"The findings and conclusions in this presentation have not been formally disseminated by the National Institute for Occupational Safety and Health and should not be construed to represent any agency determination or policy."

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Issues for Developing Standard Materials

• Identification of needs and candidate materials

• Standard methods to produce well-characterized materials

• Standard methods utilizing well-characterized materials

• Categories of certified and other types of reference materials

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NIOSH-NIST Collaborations on Reference Materials for EHS

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NIOSH-NIST Collaborations on Reference Materials for EHS

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1. Prioritize research based on the value of information. • the extent to which information gained from

investment in research funding will reduce uncertainty about both benefits and risks of nanomaterials;

• the extent to which information may lead to broad knowledge about properties and behavior of nanomaterials or classes of nanomaterials;

• the extent of use expected for a nanomaterial or groups of nanomaterials; potential of worker, consumer, or environmental exposure to nanomaterials.

2. Where appropriate, seek to leverage research funded by other governments and the private sector.

3. Use adaptive management for nanomaterial EHS research.

NNI Prioritization Criteriafor EHS Research Needs

www.nano.gov/NNI_EHS_research_needs.pdf

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Risk Assessment and Risk Management Framework

1 2 3 4

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Hazard identification

Hazard characterization

Riskcharacterization

Exposure assessment

RiskManagement

“Is there reason to believe this

could be harmful?”

“How and under what conditions

could it be harmful?”

“Is substance hazardous and

will there be exposure?”

“Will there be exposure inreal-world

conditions?”

“Develop procedures to

minimize exposures”

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Re-evaluation

“Are there new data?”

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Standard-Material Matrix for Risk Assessment and Risk Management

Basic Applied

Hazard Exposure Controls Hazard Exposure Controls

Occupational

General public

Environment

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Toxicity and Internal Dose • Investigating and determining the physical and chemical properties

(ex: size, shape, solubility) that influence the potential toxicity of nanoparticles

• Evaluating short and long-term effects that nanomaterials may have in organ systems and tissues (ex: lungs)

• Determining biological mechanisms for potential toxic effects • Creating and integrating models to assist in assessing possible

hazards • Determining if a measure other than mass is more appropriate for

determining toxicity Fire and Explosion Safety• Identifying physical and chemical properties that contribute to

dustiness, combustibility, flammability, and conductivity of nanomaterials.

• Recommending alternative work practices to eliminate or reduce workplace exposures to nanoparticles.

NIOSH Nanotechnology Critical Topic Areas: Hazard

http://www.cdc.gov/niosh/topics/nanotech/critical.html

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1. Basic: Factors influencing health hazards (toxicity, pharmacokinetics) and physical hazards (explosivity, flammability)

2. Applied: Work-related exposures (mixtures, impurities, distribution of nanomaterials properties)

Criteria considerations for hazard assessment

28 days post exposure 40 g/mouse SWCNT

20 microns

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Exposure Assessment • Determining key factors that influence the production, dispersion,

accumulation, and re-entry of nanomaterials into the workplace • Assessing possible exposure when nanomaterials are inhaled or

settle on the skin • Determining how possible exposures differ by work process • Determining what happens to nanomaterials once they enter the body

Measurement Methods• Evaluating methods of measuring mass of respirable particles in the

air and determining if this measurement can be used to measure nanomaterials

• Developing and field-testing practical methods to accurately measure airborne nanomaterials in the workplace

• Developing testing and evaluation systems to compare and validate sampling instruments

NIOSH Nanotechnology Critical Topic Areas: Exposure

http://www.cdc.gov/niosh/topics/nanotech/critical.html

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1. Basic: Factors influencing generation (dustiness, sticking coefficient, agglomeration); routes of exposure; deposition and translocation models; exposure metric

2. Applied: Calibration of instrumentation (calibration reference material); method validation (matrix reference material)

Criteria considerations for exposure assessment

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Engineering Controls and PPE • Evaluating the effectiveness of engineering controls in

reducing occupational exposures to nanoaerosols and developing new controls where needed

• Evaluating and improving current personal protective equipment

• Developing recommendations to prevent or limit occupational exposures (ex: respirator fit testing)

• Evaluating suitability of control banding techniques where additional information is needed; and evaluating the effectiveness of alternative materials

NIOSH Nanotechnology Critical Topic Areas: Controls

http://www.cdc.gov/niosh/topics/nanotech/critical.html

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1. Basic: Factors influencing transport/penetration and precipitation (aerodynamic diameter and drag, diffusion coefficient, sticking coefficient, agglomeration)

2. Applied: PPE and respirator testing; testing of engineering controls

Criteria considerations for exposure controls

Nanoscale alumina on cotton fabric

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Proposed Selection Criteria: Mission Oriented

Criteria Basic Applied

What are we trying to achieve?

Provide the foundation

for protective and predictive models

Provide information relevant to existing and

emerging materials, processes, instruments,

and methods

How can we achieve this given the uncertainties?

Focus on materials that will support expert

level understanding and expert judgment

skills that can be generalized

•Survey the industry:Amounts of materials

•Conduct health surveillance:

Adverse effects

•Engage stakeholders 

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Proposed Selection Criteria: Feasibility Considerations

Criteria Basic Applied

Do we have or can we get this material?

•Sufficient availability•Stability of generation

method•Stability and

uniformity of material

•Actual applications•Stability of process

environment•Stability and uniformity

of material

Is or can this material be properly and adequately characterized?

•Broad range of parameters

•Application-critical parameters

By whom and how extensively will this reference material be used?

•Costs•Market (researchers)

•Costs•Market (production and

EHS professionals)

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1. OSH TR: chemistry and dimensionality based grouping• Carbonaceous• Oxides• Metals• Semiconductors• Organic polymeric • Bio-inspired

2. TR on Physical-chemical properties for toxicology studies

3. Standards for Nano-silver particle generation for toxicology studies

Nano EHS Standards in ISO

Allotropes of carbon

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Nanoparticle Occupational Safety and Health (NOSH) Consortium

• Generate well-characterized aerosol nanoparticles of various chemistries

• < 100 nm• various chemistries: TiO2, SiO2, carbon black, silver, latex

reference material, citric acid• materials of interest to consortia members• aerosol synthesis methods (in situ and re-aerosolization)

• Applications• Develop a portable air sampling method for daily monitoring of

R&D and manufacturing settings• Measure filtration efficiency of filter media to specific engineered

nanoparticles

Michele Ostraat, DuPont

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PhiX174 bacteriophage

• Small size• Spherical or polyhedral• Environmental stability• Low or non-human infectivity• High assay sensitivity• Rapid growth• High titer

ASTM F1671-03 Standard Test Method for resistance of materials used in protective clothing to penetration by blood-borne pathogens using Phi-X174 bacteriophage penetration

H.-W. Ackermann, Laval University, Quebec

100 nm

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Criteria• A representative matrix

reference material• Commonly used CNT-

production method

• An adequate amount for calibration, quality assurance, and inter-comparison studies• Validation of product quality,

purity and consistency• Toxicity studies• Calibration and validation of

EHS methods

SWCNT-bearing Reference Material(candidate NIST RM 8475)

NIST-NIOSH-and others collaboration

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BeO Powder Standard Reference Material(candidate SRM 1877)

• Criteria• A continuing safety and health concern

(chronic beryllium disease)• Well characterized respirable powder of

common commercial form• Meets requirements for uniformity,

physical form, other measured quantities • Stability of production protocol• Continued availability

• Morphology• Clusters of primary particles

• Composition• High purity BeO• Primary particles

- Powder: 190 nm- Workplace particles: 220 nm

NIST-NIOSH-DOE collaboration

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1. What are critical research and workplace EHS needs requiring reference materials?

2. Is a candidate material critical for addressing an EHS research priority and/or for ensuring safety and health in the workplace? Will the demand for this material be sufficiently* high?

3. Does the candidate material represent a widely produced nanomaterial or a broad class of nanomaterials?

4. Is this material available in sufficient* quantities and of sufficient* homogeneity as a one-time batch or through a stable, reproducible process to be a reference material?

5. Can this material be sufficiently* characterized?

6. What financial model will be used and will the material be affordable?

Criteria for Discussion

*dependent upon the intended uses of the reference material