Biomedical Engineering Reference
In-Depth Information
is determined as “unknown,” 75% of the highest point value would be assigned for that factor. The
two overall scores each have a maximum point of 100, stratified across four levels. The hazard
severity score and exposure probability score result in a 4 × 4 matrix with its intersections forming
bands of RL, as shown in Figure 2.5.
The four levels of risk are then linked to the four corresponding control bands as follows:
RL 1: General ventilation
RL 2: Fume hoods or local exhaust ventilation
RL 3: Containment
RL 4: Seek specialist advice
As shown above, the CB Nanotool needs rather comprehensive information for hazard banding,
and thus requires the involvement of IH professionals. A spreadsheet of CB Nanotool 2.0, along
with instructions for scoring and a Nanomaterial Information Form for data collection is available
at http://www.controlbanding.net.
In light of numerous uncertainties, the CB Nanotool and other CB tools provide a relatively simple
yet efficient instrument that can facilitate risk management. As with any qualitative and quantitative
risk assessment methods, there are limitations to the CB approach. For example, the selected hazard
and exposure factors, and the scoring of these factors, only reflect what is known at the time of the
development of the model. In addition, there is currently very limited toxicological data from which
to determine the appropriate control levels. As a result, the CB should be implemented with some
degree of caution, and continually be refined when new information on nanomaterial toxicity and
exposure data and more validation studies become available. Finally, it is important to recognize that
CB is
not
a replacement for IH professionals, nor does it eliminate the need for quantitative exposure
assessments.
2.7 CONCLUSIONS
The field of nanotechnology is rapidly evolving and expanding and, thus, the number of workers that
could potentially be exposed to a wide variety of nanomaterials will increase. The unique physio-
chemical properties of some of these nanomaterials are shown to pose safety and health risks that are
not anticipated from their bulk materials. Until new information on their toxicity and exposure become
available, it is at present necessary to take precautionary measures to minimize workers' exposures to
hazardous nanomaterials. Prudent practices and preventive measures should be implemented accord-
ing to the traditional IH hierarchy of control in the following order whenever possible: PtD, engineer-
ing controls, administrative controls, the use of PPEs, and occupational health surveillance.
In the face of numerous uncertainties, the CB strategy emerges as a simple yet efficient approach
to directing limited resources to areas where it is needed the most, that is, exposure control. It offers
desired control advices and solutions based on the level of risk determined by bands of hazard
severities and exposure probabilities. It is important to recognize that CB is intended as a comple-
ment to IH professions, not a replacement, and it is particularly useful when limited knowledge is
known about the hazard and exposure. With that being said, the effectiveness of CB builds upon
up-to-date knowledge as well as sound IH principles. As a result, the CB should be implemented
with some degree of caution, and continually be refined when new information becomes available.
REFERENCES
ACGIH (American Conference of Industrial Hygienists). 2010.
Industrial Ventilation: A Manual of
Recommended Practice
, 27th ed., Cincinnati, OH: ACGIH, USA.
Adeleye, A., Huang, D., Layton, Z., Paladugu, S., Twining, J. 2011. CERNS: A condensed environmental
health & safety reference for nanotechnology startups. Master's thesis, University of California-Santa
Barbara, CA, USA.
