The Parameters List

Recommended Minimum Physical and Chemical Parameters for Characterizing Nanomaterials on Toxicology Studies

Note:  This is a recommended minimum set of parameters, and is not intended to replace more robust guidelines from governments and organizations such as ISO and OECD

What does the material look like?

• Particle size/size distribution
• Agglomeration state/Aggregation
• Shape

What is the material made of?

• Overall composition (including chemical composition and crystal structure)
• Surface Composition
• Purity (including levels of impurities)

What factors affect how a material interacts with its surroundings?

• Surface Area
• Surface Chemistry, including reactivity, hydrophobicity
• Surface Charge

Overarching considerations to take into account when characetrizing engineered nanomaterials in toxicity studies:

• Stability—how do material properties change with time (dynamic stability), storage, handling, preparation, delivery etc?  Include solubility, and the rate of material release through dissolution.
• Context/Media—how do material properties change in different media; i.e. from the bulk material to dispersions to material in various biological matrices? (“as administered” characterization is considered to be particularly important)
• Where possible, materials should be characterized sufficiently to interpret the response to the amount of material against a range of potentially relevant dose metrics, including mass, surface-area and number concentration.

(These recommendations were developed at a workshop on ensuring appropriate material characterization in nano-toxicity studies, held at the Woodrow Wilson International Center for Scholars in Washington DC between October 28-29, 2008)

A PDF of these recommendations is available here (116 KB)