Nanotechnology and the use of unbound engineered nanoparticles (UNP) is a
rapidly developing area of material science. Unbound engineered nanoparticles
are defined as engineered nanoparticles that are not contained within a matrix
that would prevent the nanoparticles from being mobile and a potential source of
exposure. At this time there are no regulatory environmental release limits or
worker exposure limits for unbound engineered nanoparticles. Some preliminary
consensus standards have been issued, but they are still under development by
In an effort to evaluate worker exposure and potential environmental release
of unbound engineered nanoparticles at Lawrence Berkeley National Laboratory, a multi-phase pilot
study was initiated in the summer of 20091,2. RJ Lee
Group, Inc. was retained to assist in the design, setup, and implementation
of the study. The goals of the pilot study are to comply with Department of
Energy (DOE) Notice N456.1, The Safe Handling of Unbound Engineered
Nanoparticles3 and meet the requirements of the
DOE Nanoscale Science Research Centers Approach to Nanoscale ES&H4.
What is Control Banding
A control banding approach is being used to provide guidance on risk
management of UNP at Lawrence
Berkeley National Laboratory. Originally developed in the pharmaceutical
industry, control banding is a qualitative method for summarizing risks and
controls5. It is a concept that is applicable to the
field of engineered nanomaterials where there is incomplete information on
hazard and exposure6,7,8. Control banding utilizes basic characteristics of a
process and its material(s) to determine a generalized risk level, either
environmental or occupational.
This information can then be matched to a level of control best suited for
the process. The outcome of the control banding process suggests or helps define
the appropriate level of control for a process. When the control is appropriate
for the risk, the hazard is successfully mitigated. Studies indicate that
control banding is highly successful at determining adequate controls when
validated by subsequent professional evaluations and workplace monitoring9. The control banding process being employed in this pilot
study is based on the following algorithm:
The Worker/Environmental Hazard categories are based primarily on
risk attributes such as dustiness, chemistry, and suspected toxicity (low,
medium, high, very high/unknown). The Release/Exposure Probability categories
are based on the ability of a material to become dispersed (unlikely, low,
likely, probable). The Risk (Degree of Hazard) Level rankings range from
relatively safe, 1A to the highest degree of risk, 4D, depending on the
categories determined above.
The level of control for a process should be directly matched to the risk;
that is, a low level of control is generally matched to a low level of risk,
whereas higher risk indicates the need for a higher level of control. Controls
may exceed the level of risk but should not be less than the level indicated by
the risk. The preliminary control bands developed for Lawrence Berkeley National
Laboratory illustrating the relationship of the probability of
release/exposure to potential toxicity or severity are shown in a matrix form in
Figure 1. LBNL
Preliminary Control Banding Matrix.
Lawrence Berkeley National Laboratory Pilot Study
To establish preliminary control bands, Phase I of the project involved
discussions with the researchers and observation of processes involving fume
hoods, glove boxes, counter tops and ablation systems. In addition, a key
component of Phase I was the characterization of the starting (source) UNP
materials. Samples of UNP materials used in process activities were obtained
from the researchers, and these samples were analyzed using ICP and/or electron
microscopy to establish source signatures of the various starting UNP materials.
For instance, in one laboratory gold nanorods are being studied for use in
sensor applications. The milligram quantities of input material is obtained in
an aqueous solution and manipulated within a functional laboratory exhaust hood.
The source material was analyzed in a high-resolution scanning electron
microscope (SEM) and found to be primarily rod-shaped particles approximately 20
nanometers in diameter and approximately 50 nanometers in length, as shown in
Figure 2. Secondary
electron microscopy images of gold nanorods analyzed in a Hitachi S-5500 high
The Phase II study activities involved the development of preliminary control
bands. Based on the characterization of the source material as described for the
gold nanorods, a review of process activities, and an assumed toxicity, a table
of risk attributes specific to the material was generated. The table of risk
attributes for the gold nanorods is shown in Table 1. A preliminary control band
was then established for this process, as shown in Table 2.
Table 1. Risk Attributes for Gold Nanorods
Rod-shaped particles ~20 nanometers (nm) in diameter and ~50 nm in length;
rounded and spherical particles were ~40-50 nm in diameter
Primarily rod-shaped particles; rounded and spherical particles; observed in
Toxicity of Nanomaterial
Amount of Material Used
Number of People Doing the Work
Duration of Operation
Frequency of Operation
Table 2. Preliminary Control Bands for Gold Nanorods
Preliminary Control Bands for Gold
Preliminary Control Band
A preliminary control level II (refer to Fig. 1) was assigned to this process
based on the category 2 release/exposure probability and category C
worker/environmental hazard. Lawrence Berkeley National Laboratory is performing research
activities using this material with level II controls in place for this process.
Thus, the current level of controls for this process conforms to the control
level indicated by the preliminary control band.
In Phase III, the preliminary control bands will be evaluated further and
modified, as appropriate, based on data obtained through process and worker
exposure sampling. The sampling methodology in Phase III will incorporate both
real time particle counters and filtration-based particle collection
Nanotechnology represents the next frontier in materials science with
seemingly unlimited opportunities. Yet there is concern related to the potential
toxicity associated with engineered particles in the nano size range10. We have built a foundation in research methods,
characterization techniques, analytical instrumentation, and control
This work advances the knowledge base and experience to move forward in a
safe manner in the emerging field of nanotechnology. The work being performed at
Lawrence Berkeley National
Laboratory builds on this foundation and puts into practice a methodology
that can be used to reduce risks to the worker and the environment related to
the use of nanomaterials.
The authors would like to acknowlege Leo Banchik, Jay James, Guy Kelley, Don
Lucas, Ron Pauer and Tim Roberts at Lawrence Berkeley National Laboratory for their contributions
to the study.
1. Casuccio, G., Ogle, R., Wahl, L., and Pauer, R., "Worker and
Environmental Assessment of Potential Unbound Engineered Nanoparticles Releases:
Phase I Final Report," RJ Lee Group, Inc., and Lawrence Berkeley National
Laboratory, September 2009.
2. Casuccio, G., Ogle, R., Wahl,
L., and Pauer, R., "Worker and Environmental Assessment of Potential Unbound
Engineered Nanoparticles Releases: Phase II Final Report," RJ Lee Group, Inc.,
and Lawrence Berkeley National Laboratory, September 2009.
Department of Energy, The Safe Handling of Unbound Engineered Nanoparticles, DOE
N456.1, 5 January 2009.
4. Department of Energy, Nanoscale
Science Research Centers, Approach to Nanomaterial ES&H, Revision 3a, DOE
Office of Science, 12 May 2008.
5. NIOSH Publication No.
2009-152: Qualitative Risk Characterization and Management of Occupational
Hazards: Control Banding (CB), Published August 17, 2009, http://www.cdc.gov/niosh/docs/2009-152/.
Zalk, D. M. and Nelson, D. I., "History and Evolution of Control Banding: A
Review," Journal of Occupational and Environmental Hygiene, 5:5, 330-346,
7. Maynard, A.D., "Nanotechnology: The Next Big Thing, or
Much Ado about Nothing?," Annals of Occupational Hygiene, 51:1, 1-2, 2007.
8. Kulinowski, K. M., "Temptation, Temptation,
Temptation: Why Easy Answers About Nanomaterial Risk are Probably Wrong,"
AZoNano.com, November 15, 2009.
9. Hashimoto, H. G., et. al.,
"Evaluation of the Control Banding Method-Comparison with Measurement-based
Comprehensive Risk Assessment," Journal of Occupational Health, Nov. 2007,
49(6):482-92, http://www.ncbi.nlm.nih.gov/pubmed/18075208, accessed 28
10. Lee, R.J., "Nanomaterials - Securing the Future with Lessons from the
Past,"AZoNano.com, November 15, 2009.
Copyright AZoNano.com, Dr. Kristin Bunker (RJ Lee Group
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