“The identification of hazards is the first step in determining risk and exposure. This step involves identifying chemicals or nanomaterials, and their associated processes that pose toxic, physical (e.g. high levels of noise, high pressures and vacuums, strong electromagnetic flux, etc.) and physicochemical hazards. In a comprehensive hazard identification process, all potential occupational hazards, including workplace chemicals should be identified in this step, including hazards that are low-level hazards or of low exposure potential, or hazards already being controlled in the workplace.”¹

“The following are indicators of potential toxicity that should be considered when deciding on an appropriate testing strategy:

• High level of reactivity (e.g. catalytic, chemical, biological)
• Complex morphology (e.g. rigid, long tubes or fibres, high aspect ratio nanomaterials, fullerenes, crystal structure, porosity).
• ENM with cores and shells of different biopersistence (e.g. multifunctional ENM)
• Interactions with biomolecules such as enzymes, DNA, receptors, “Trojan horse” effect
• Complex transformations (e.g. aging, changes of surface properties, porosity) or metabolites (e.g. changes to or loss of coating (dynamic corona))
• ENM intended to be used as antimicrobials (e.g. unintended consequences on the gut flora).”²

A. Physicochemical Characteristics³

“There is little consensus for the relative significance of the physical and chemical characteristics of unbound, engineered nanoscale particles as an indicator of toxicity. However, current research indicates that particle size, surface area, and surface chemistry (or activity) may be more important metrics than mass and bulk chemistry.”⁴

B. Toxicity Characteristics

“For nanomaterials there are several potential sources of toxicological effects, including those that relate to the chemical properties of the bulk material and also those that relate specifically to the nanomaterial form. In some cases the bulk toxicological properties are well-defined, whereas the nanomaterial-specific properties are little-known (Nel et al. 2006). Recent toxicological studies have also been performed on relatively new engineered nanomaterials, such as CNTs, that have exhibited toxicity not previously seen in the bulk form of the same chemical (Poland et al. 2008).“5

C. Ecotoxicity Characteristics

D. Hazard Class Assignment

E. Hazard Communication Plan

As an alternative, British Standards recommends the following four groups as a useful starting point in assessing the hazard associated with a particular engineered nanomaterial. British Standards states that it is a reasonable assumption the nanomaterials categorized in these four groups “have a hazardous potential which is greater than that of the larger, non-nanoscale forms of the material.”

• Fibrous nanomaterials – “a high aspect ratio insoluble nanomaterial”
• “CMAR” nanomaterials – “any nanomaterial which is already classified in its larger particle form as carcinogenetic, mutagenic, asthmagenic or a reproductive toxin” (hence “CMAR”).
• Insoluble nanomaterials – “insoluble or poorly soluble nanomaterials not in the fibrous or CMAR category.”
• Soluble nanomaterials – solubabe nanomaterial “not in fibrous or CMAR category.“6

1. Safe Work Australia, “Engineered Nanomaterials: Evidence on the Effectiveness of Workplace Controls to Prevent Exposure,” at 12 (Nov. 2009) (copyright Commonwealth of Australia reproduced by permission).

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. S. Rocks, S. Pollard, R. Dorey, L. Levy, P. Harrison and R. Handy, “Comparison of Risk Assessment Approaches for Manufactured Nanomaterials”. Report complied as part of Defra project (CB403), Final Report, 55 (30 May 2008). The following three risk assessment frameworks are listed and discussed in “Comparison of risk assessment approaches for manufactured nanomaterials,” a report compiled as part of Defra project (CB403): pharmaceutical risk assessment; occupational risk assessment; and chemicals risk assessment. The report describes the occupational risk assessment framework as, “arguably, the most developed system for the control of chemical exposure.” “All occupational risk assessments require the employer to assess the substance toxicity (e.g. using material safety and hazard data sheets), the likelihood of worker exposure and exposure of other individuals and, how exposure can be prevented or controlled so as to avoid/minimize risk. Occupational exposure limits (OELs, airborne standards designed to protect health from acute or chronic effects so far as inhalation is concerned) are defined for substances normally as an average over a reference time period (e.g. 8 hours; also referred to as Time Weighted Average; TWA). OELs have been used since 1930’s for specific substances (e.g. cotton dust . . .). Threshold limit values (TLV) are also used as airborne standards for occupational risk assessment.”

4. ASTM International, “Standard Guide for Handling Unbound Engineered Nanoscale Particles in Occupational Settings,” E2535-07, § 7.1.1 (Oct. 2007)

5. Safe Work Australia, “Engineered Nanomaterials: Evidence on the Effectiveness of Workplace Controls to Prevent Exposure,” at 13 (Nov. 2009)(citing Nel AE, Xia T, Madler L & Li N (2006). Toxic potential of materials at the nano level. Science 311(5761): 622-627 and Poland CA, Duffin R, Kinloch I, Maynard A, Wallace WAH, Seaton A, Stone V, Brown S, MacNee W & Donaldson K (2008). Carbon nanotubes introduced into the abdominal cavity of mice show asbestos-like pathogenicity in a pilot study. Nature Nanotechnology 3(7): 423-428 (copyright Commonwealth of Australia reproduced by permission).)

6. British Standards, Guide to safe handling and disposal of manufactured nanomaterials,” PD 6699-2:2007, at 9 (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.”)