* Dustiness
The European Food Safety Authority established the following table to characterize engineered nanomaterials prior to use in food/feed related applications. That said, the guidance provided in this table should be of assistance in other applications:
“Parameters for characterization and identification of ENM”1
| Parameter | Requirements | Description |
|---|---|---|
| Chemical composition/ identity | Essential | Information on chemical composition of the ENM including purity, nature of any impurities, coatings or surface moieties, encapsulating materials, processing chemicals, dispersing agents and/or other formulants e.g.stabilisers. |
| Particle size (Primary/Secondary) | Essential(two methods, one being electron microscopy) |
Information on primary particle size, size range and number size distribution (indicating batch to batch variation “ if any). The same information would be needed for secondary particles (e.g. agglomerates and aggregates) if present. .
|
| Physical form and morphology | Essential | Information on the physical form and crystalline phase/shape. The information should indicate whether the ENM is present in a particle-, tube-, rod-/shape, crystal or amorphous form, and whether it is in free particulate form or in an agglomerated/aggregated state as well as whether the preparation is in the form of a powder, solution, suspension or dispersion. |
| Particle and mass concentration | Essential for dispersions and dry powders | Information on concentration in terms of particle number and particle mass per volume when in dispersion and per mass when as dry powder. |
| Specific surface area | Essential for dry powders | Information on specific surface area of the ENM. |
| Surface chemistry | Essential (for ENM with surface modifications) |
Information on ENM surface “ including any chemical/ biochemical modifications that could modify the surface reactivity, or add a new functionality.
|
| Surface charge | Essential | Information on zeta potential of the ENM. |
| Redox potential | Essential for inorganicENMs | Information on redox potential. Conditions under which redox potential was measured need to be documented. |
| Solubility and partition propertiesa | Essential |
Information on solubility of the ENM in relevant solvents and their partitioning between aqueous and organic phase (e.g. as log Kow if appropriate).
|
| pH | Essential for liquiddispersions | pH of aqueous suspension. |
| Viscosity | Essential for liquid dispersions | Information on viscosity of liquid dispersions. |
| Density and pour density | Essential for granular materials | Information on density/porosity of unformulated ENM and pour density. |
| Dustiness | Essential for dry powders | Information on dustiness of powder products such as spices, creamers and soup powders. |
| Chemical reactivity/catalytic activityb | Essential | Information on relevant chemical reactivity or catalytic activity of the ENM and of any surface coating of the ENM. |
| Photocatalytic activity | Essential for photocatalytic materials | Information on photocatalytic activity of relevant materials used in food packaging, coatings, and printing inks and internal reactions. |
a) Dispersion, solution, dissolved: An insoluble ENM introduced to a liquid form a ˜dispersion™ where the liquid and the ENM coexist. In a true solution the ENM is dissolved (and thus not present) (see OECD ENV/JM/MONO(2010)25)
b) If an ENM has catalytic properties, it may catalyse a redox or other reaction that may perpetuate resulting in a much larger biological response even with small amounts of the catalytically active ENM. Thus, compared to a conventional biochemical reaction that uses up the substrate, ENM reaction centres may perpetuate catalytic reactions.
1. 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 13 (see appendix A for characterization methods).