Radiation Safety Aspects of Nanotechnology

Radiation Safety Aspects of Nanotechnology Celebrating the 100th Anniversary of Radioactivity at NPL Airborne Radioactivity Monitoring Users Group 3 J...
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Radiation Safety Aspects of Nanotechnology Celebrating the 100th Anniversary of Radioactivity at NPL Airborne Radioactivity Monitoring Users Group 3 June 2013

Mark D. Hoover, PhD, CHP, CIH 304-285-6374

[email protected] National Institute for Occupational Safety and Health Morgantown, West Virginia

The findings and conclusions in this presentation are those of the author and do not necessarily represent the views of the National Institute for Occupational Safety and Health. Mention of company names or products does not constitute endorsement by NIOSH.

Nano-enhanced materials and processes are raising issues in radiation-related operations.

 What are the sources of radiation-related nanomaterials?  How can exposure be assessed over life-cycle processes?

How should radiation dosimetry be conducted for nanomaterials?

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About the National Council on Radiation Protection and Measurements (NCRP) • Created in 1929 as the U.S. Advisory Committee on X-ray and Radium Protection. • Congressionally chartered in 1964 as a not-for-profit service organization by U.S. Public Law 88-376 to serve in the Nation’s public interest for collecting, analyzing, and disseminating the latest scientific information about radiation protection and measurement. • Cooperates with national and international governmental and private organizations to facilitate the effective use of combined resources to further develop the basic concepts of radiation protection and measurement. 3

NCRP is developing a commentary on radiation safety aspects of nanotechnology.

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Commentary Objective • Provide practical operational information for – radiation safety officers, – operational health physicists, – dosimetrists, – workers, – management, and – regulators.

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Commentary Scope • Radiation health and safety issues related to – Use of radiation to characterize or alter materials at the nanoscale level, – Radiolabelling of nanomaterials for tracking or evaluation of physicochemical and biological behavior, and – Use of nano-formulated materials in situations involving radiation or radioactivity. 6

Nanotechnology: A spectrum of activities

Many similarities to nuclear industries

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We can partner to develop a comprehensive risk management scheme to:

• • • • •

Anticipate, Recognize, Evaluate, Control, and Confirm

Training

Hoover et al., Synergist 22(1): 10, 2011.

success in our management of the radiation safety aspects of nanotechnology

by applying a science-based approach to understanding and managing the critical elements over which we have control.

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It makes sense to manage nanoparticles as a component of a traditional Radiation or Chemical Hygiene Program. • • • • • • • • • • •

Basic Rules and Procedures Chemical Procurement, Distribution, and Storage Environmental Monitoring Housekeeping, Maintenance, and Inspections Medical Program Personal Protective Apparel and Equipment Records Signs and Labels Spills and Accidents Training and Information Waste Disposal 9

Particle size-dependent deposition in the human respiratory tract is a critical factor. Deposition Fraction

1 0.9 0.8 0.7 0.6 0.5 0.4 Total

0.3

Head Airways Tracheo-Bronchial

0.2

Alveolar

0.1 0 0.001

0.01

0.1

1

10

100

Particle Diameter (µm) Calculated from the ICRP 66 model for an adult male, light exercise, nose breathing. 10

Radioactive nanoparticles need to be studied in more detail.

Committed effective dose Preliminary data analyses suggest higher urinary excretion per unit measured activity of nano-Pu-239 in urine is higher for larger particles. compared to the default Thus, bioassay interpretation based on the 5-µm particle size. default particle size should be protective. Better sizing of particles will lead to better dosimetry.

Courtesy of L. J. Cash

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Current Challenges: • The traditional assessment and management strategy requires an occupational exposure limit (OEL).

Hierarchy of Exposure Control Practices

Elimination

• OELs for radioactive materials are based on a unified concept of dose.

Substitution

• Such a unifying concept is not available for nanoparticles.

Modification Containment

• How can an effective chemical hygiene program for nanotechnology be developed and implemented in the absence of comprehensive OELs? • What control approaches are feasible and effective?

Ventilation Work Practices Personal Protection 12

A Hierarchical Vision of Hazard and Exposure Control for Comprehensive Health Protection, Health Promotion, and Well-being

Sustainability

Safety, Health, and Well-being

We have retrospective, contemporaneous, and prospective opportunities.

Elimination Substitution Modification

Work Practices

Safety, Health, and Well-being by Design

Containment and other engineered controls

Multiple hazards may be relevant. Personal Protective Equipment

Safety, Health, and Well-being by Procedure

Potential Hazard x Potential Exposure = Potential Risk

Draft for discussion

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A Hierarchical Vision of Hazard and Exposure Control for Comprehensive Health Protection, Health Promotion, and Well-being Safety, Health, and Well-being

Elimination Substitution

Sustainability

Modification

Work Practices

Safety, Health, and Well-being by Design

Containment and other engineered controls PPE Potential Risk

Safety, Health, and Well-being by Procedure

Potential Hazard x Potential Exposure = Potential Risk

Draft for discussion

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A Hierarchical Vision of Hazard and Exposure Control for Comprehensive Health Protection, Health Promotion, and Well-being Safety, Health, and Well-being

Elimination

Sustainability

Substitution Modification

Work Practices

Safety, Health, and Well-being by Design

Containment and other engineered controls Potential Risk

PPE

Safety, Health, and Well-being by Procedure

Potential Hazard x Potential Exposure = Potential Risk

Draft for discussion

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A Hierarchical Vision of Hazard and Exposure Control for Comprehensive Health Protection, Health Promotion, and Well-being

Sustainability

Safety, Health, and Well-being

Elimination Substitution Modification

Safety, Health, and Well-being by Design

Potential Risk

Work Practices

Containment and other engineered controls

Personal Protective Equipment

Safety, Health, and Well-being by Procedure

Potential Hazard x Potential Exposure = Potential Risk

Draft for discussion

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A Hierarchical Vision of Hazard and Exposure Control for Comprehensive Health Protection, Health Promotion, and Well-being

Sustainability

Safety, Health, and Well-being

Elimination Substitution Modification

Work Practices

Safety, Health, and Well-being by Design

Containment and other engineered controls Personal Protective Equipment

Safety, Health, and Well-being by Procedure

Potential Hazard x Potential Exposure = Potential Risk

Draft for discussion

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A Hierarchical Vision of Hazard and Exposure Control for Comprehensive Health Protection, Health Promotion, and Well-being

Sustainability

Safety, Health, and Well-being

We have retrospective, contemporaneous, and prospective opportunities.

Elimination Substitution Modification

Work Practices

Safety, Health, and Well-being by Design

Containment and other engineered controls

Multiple hazards may be relevant. Personal Protective Equipment

Safety, Health, and Well-being by Procedure

Potential Hazard x Potential Exposure = Potential Risk

Draft for discussion

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Conventional Controls Should Work Exhaust Ventilation Capture Diffusion Dominates

About 1 nm 200 to 300 nm Most Fine Dusts

Inertia Dominants

No Capture

Micro Scale

Air Stream

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Particle penetration through personal protective equipment: N95 respirators • Use of respiratory protection for nanomaterials professional judgment and hazard assessment 3.0 % Penetration

2.5 2.0 1.5 1.0 0.5 0.0 1

10

100

1000

Particle Size (nm)

Maximum penetration is in the region of minimal Brownian motion and minimal inertial effects

Silver

Sodium chloride

n = 5; error bars represent standard deviations Flow rate 85 L/min; NIOSH Approved N95 (NPPTL)

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Developing an Effective Control Strategy mild / reversible

Occupational Health Hazard

severe / irreversible 8 hours

Closed Systems

Engineered Local Exhaust Ventilation

Laboratory Hoods

milligrams

General Ventilation agglomerated

Glovebox Enclosures

highly dispersible Physical Form powder Adapted from Heidel, in NIOSH Approaches to Safe Nanotechnology 2009 slurry or suspension

Task Duration

Quantity

kilograms

15 minutes

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Key guidance is available from NIOSH. 3-15-2010 DRAFT

NIOSH Current Intelligence Bulletin Occupational Exposure to Carbon Nanotubes

English Spanish Portuguese Italian Japanese

www.cdc.gov/niosh/topics/nanotech

DEPARTMENT OF HEALTH AND HUMAN SERVICES Centers for Disease Control and Prevention National Institute for Occupational Safety and Health

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A technical report is also being developed on measurement and characterization. • International Electrotechnical Commission – Technical Committee 45 (Nuclear Instrumentation) – Scientific Committee 45B (Radiation Protection Instrumentation) • Technical Report on Radiation Protection Instrumentation Issues for Particles including Nanomaterials – Clarifying current practice – Identifying critical gaps – Attention to issues for workplace and offsite dispersion • Input is welcome – The writing group will meet in Moscow in June 2013.

International collaboration on consensus standards

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Characterization Methods

• Particle number • Mass concentration • Size distribution (by count or mass) • Surface area • Qualitative – Morphology – Extent of agglomeration – Complexity

• Confirmation – e.g. TEM with elemental analysis

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Graded Approach to exposure assessment and control Level 1

Level 2

Level 3

Initial Screening and Detection

Comprehensive Characterization and Assessment

Routine Monitoring and Control

• Process knowledge • Gross mass or activity counting • Optical particle counting • Condensation particle counting • Microscopy

• Composition - Elemental and chemical

• Particle size - Physical - Aerodynamic - Thermodynamic - Electrical mobility

• A necessary and sufficient subset of Level 1 and 2 methods for the material and situation of interest

• Exposure Concentrations - Peaks, averages, variability

• Biophysical properties - Shape, surface area, solubility

• Other factors relevant to the assessment

Adapted from Hoover 2011

Essential for cost and feasibility 25

Characterization Methods Overview Periodic Performance Testing

Mission Evaluation

Research and Development Prototype Testing

Maintenance and Recalibration

Operational Experience

A Life-Cycle Approach for Instrumentation and Methods

Type Testing

Production Control Testing

Functional Checks Initial Calibration

Acceptance Testing

Training

Successful approaches address all issues Hoover and Cox, 2004 and 2011 http://www.aiha.org/insideaiha/Documents/DREAM%20Radiation.pdf http://www.nano.gov/node/848

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Questions ? Mark D. Hoover, PhD, CHP, CIH NIOSH Nanotechnology Research Center and Division of Respiratory Disease Studies National Institute for Occupational Safety and Health Centers for Disease Control and Prevention 1095 Willowdale Road Morgantown, West Virginia 26505-2888 Phone: 304-285-6374 Email: [email protected]

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