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Assess Potential Exposures

“The key deliverable from this step is an exposure characterization; a summary and synthesis of the gathered exposure information. The exposure characterization should include:

a) a statement of purpose, scope, level of detail, and the approach used in the assessment;

b) estimates of exposure and dose by pathway, both for individuals and populations; and

c) an evaluation of the overall quality of the assessment and the degree of confidence in the exposure estimates and conclusions drawn.

Risks are associated with the nature of material and the exposures that people have to that material. Information should be collected that helps assess what the exposures might be.” 1

“The following are indicators of a potential for high exposure:

  • High production volume for the field of application
  • High mobility of the nanoform in organisms (probability of internal exposure) (e.g. transport via macrophages; transport through cell membranes, blood-brain barrier and/or placenta; drug delivery systems) and mobilization potential (e.g. infiltration, sorption, complex formation)
  • Targeted or controlled release
  • Persistence/stability (e.g. in water, fat, and body fluids, lack of solubility/degradation)
  • Bioaccumulation”2

“In general, it is likely that processes generating nanomaterials in the gas phase, or using or producing nanomaterials as powders or slurries/suspensions/solutions (i.e. in liquid media) pose the greatest risk for releasing unbound, engineered nanoscale particles. In addition, maintenance on production systems (including cleaning and disposal of materials from dust collection systems) is likely to result in exposure to unbound_engineered_nanoparticle unbound, engineered nanoscale particles if it involves disturbing or aerosolizing deposited nanomaterial. Exposures associated with waste streams containing Nanomaterials may also occur. The magnitude of exposure to unbound_engineered_nanoparticle unbound, engineered nanoscale particles when working with nanopowders depends on the likelihood of particles being released from the powders during handling.”3

“Both wet precipitation methods and gas-phase processes have the potential to cause exposure to primary unbound, engineered nanoscale particles during the synthesis stage. All processes may give rise to exposure to agglomerated unbound, engineered nanoscale particles during recovery, powder handling, and product processing. The nature of the exposure, the likely level and the probability of exposure will differ according to the specific process and the stage of the process. Similarly, the optimum strategy to control employee exposures and the efficacy of the control methods used will differ depending on the specific process.”4


Potentially Exposed Individuals:

  • Operators
  • Janitors and Maintenance Workers
  • Supervisors and Inspectors
  • Visitors and Contractors
  • Other Nearby Workers
  • Emergency Responders

Potential Exposure Routes

“Workers may be exposed to unbound_engineered_nanoparticle unbound, engineered nanoscale particles by way of inhalation, dermal contact (including eyes and mucus membranes), ingestion, or injection. The nature and extent of the exposure will depend on the physical characteristics of the engineered nanomaterials.”5

“The most common route of exposure to airborne particles in the workplace is by inhalation. The deposition of discrete nanoparticles in the respiratory tract is determined by the particle’s aerodynamic or thermodynamic diameter (depending on particle size). Agglomerates of nanoparticles will deposit according to the diameter of the agglomerate, not constituent nanoparticles. Research is still ongoing to determine the physical factors that contribute to the agglomeration and de-agglomeration of nanoparticles, and the role of agglomerates in the toxicity of inhaled nanoparticles.”6

  • Dermal Exposure (including eye and mucus membranes(external link))
  • Ingestion Exposure(external link)

“Ingestion can occur from unintentional hand to mouth transfer of materials; this can occur with traditional materials, and it is scientifically reasonable to assume that it also could happen during handling of materials that contain nanoparticles. Ingestion may also accompany inhalation exposure because particles that are cleared from the respiratory tract via the mucociliary escalator may be swallowed. Little is known about possible adverse effects from the ingestion of nanoparticles.”6

  • Injection Exposure
  • Qualitative Exposure Assessment
  • Quantitative Exposure Assessment

1. British Standards, Guide to safe handling and disposal of manufactured Nanomaterials,” PD 6699-2:2007, at (Dec. 31, 2007). (PD 6699-2:2007 provides guidance and recommendations only. The document “should not be quoted as if it were a specification and particular care should be taken to ensure that claims of compliance are not misleading.” Finally, PD6699-2:2007 “is not be regarded as a British Standard.”)

2. European Food Safety Authority, “EFSA Scientific Committee; Scientific Opinion on Guidance on the risk assessment of the application of nanoscience and nanotechnologies in the food and feed chain,” EFSA Journal 2011;9(5):2140 (36 pp.) doi:10.2903/j.efsa.2011.2140, at 10.

3. ASTM International, “Standard Guide for Handling Unbound Engineered Nanoscale Particles in Occupational Settings,” E2535-07, § A2.1.1 (October 2007)

4. ASTM International, “Standard Guide for Handling Unbound Engineered Nanoscale Particles in Occupational Settings,” E2535-07, § A2.1.2 (October 2007)

5. ASTM International, “Standard Guide for Handling Unbound Engineered Nanoscale Particles in Occupational Settings,” E2535-07, § 8.1 (Oct. 2007)

6. U.S. National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, “Approaches to Safe Nanotechnology—An Information Exchange with NIOSH, Draft for Public Comment, 6-7 (July 2006). (This paper has been distributed solely for the purpose of pre-dissemination peer review under applicable CDC/NIOSH information quality guidelines. It has not been formally disseminated by CDC/NIOSH and should not be construed to represent any CDC/NIOSH determinations or policy.)