TABLE 8.
Recommendation for exposure characterization of sampled and airborne CNT/CNF (modified from Oberdörster et al., 2005)
| Human exposure | Rodent Exposure | |||
|---|---|---|---|---|
| Characterization Type | Aerosol | Supplied material | Aerosol | Filter samples |
| Size distribution (primary particles) | E | D | E | D |
| Agglomeration/aggregation state | E | D | E | D∗ |
| Density | D | E | D | N |
| Shape | E | E | E | E |
| Surface area | O | E | D | D∗ |
| Concentration, mass and number | E | − | E | E |
| Composition | E | E | E | E |
| Surface chemistry | O | E | D | D |
| Surface contamination | D | E | D | E |
| Surface charge – suspension/solution | O | O | D | E |
| Surface charge – powder | D | O | D | E |
| Crystal structure | D | E | D | E |
| Particle physicochemical structure | D | E | D | E |
| Solubility | N | E | N | E |
| Porosity | N | E | N | N |
| Method of production | E | E | E | E |
| Preparation process | E | E | E | E |
| Heterogeneity | D | E | E | E |
| Prior storage of material | E | E | E | E |
E: These characterizations arc considered to be essential and to be available for each characterization at least once.
D: These characterizations are considered to provide valuable information, but are not recommended as essential due to constraints associated with complexity, cost and method availability.
O: These characterizations are considered to provide valuable but non-essential information.
N: These characterizations are not considered to be essential for all studies.
The CNT/CNF property is assumed to be the same as in the supplied material and therefore no need to repeat measurement. If the CNT/CNF material has been altered from that supplied (e.g., micronization), then the new properties as used in the rodent assay have to be determined.