TABLE 2.

Overview of physicochemical properties list in different literature and the result of the identified key physicochemical properties ^a .

caLIBRAte D5.3 (Nymark et al., 2017)	GUIDEnano b (pristine NM)	GUIDEnano b (NM in the exposure medium)	GRACIOUS c	OECD physicochemical decision framework d	Identified key physicochemical properties
Size/size range	Size	Size	Particle size prio		Size
Size distribution				Particle Size Distribution	Size distribution
Atomic structure/crystallinity			Crystallinity prio	Crystallinity	Crystallinity
Composition			Composition prio	Chemical Composition and Impurities	Composition
Shape/morphology	Shape		Partical shape prio	Shape	Shape
Surface chemistry			Surface chemistry prio	Surface chemistry, coating, functionalisation	Surface chemistry
Surface area	Surface area		Specific surface area prio	Specific Surface Area	Surface area/Specific surface area
Surface charge	Surface charge	Surface charge	Surface charge	Charge/zeta potential	Surface charge
Purity					Purity
Agglomeration/aggregation state				Agglomeration/Aggregation in relevant media	Agglomeration/Aggregation
Stability (solubility, dissolution rate)			Water Solubility	Dissolution rate in relevant media	Stability
					Solubility/dissolution rate
	Other information e	Other information f	Dustiness	Free radical generation capacity	Low priority parameters
			Density
			Surface hydrophobicity	Conduction band energy level
				Corrosivity

^a the aim is to identify key physicochemical properties of tested NMs, providing potential parameters for RQ, within SciRAPnano.

^b in GUIDEnano, the required nanomaterial characterization parameters are separated in two subsets: A: pristine nanoparticle; B: Nanoparticle in the exposure medium. Parameters included in this sheet are from both subsets (Fernández-Cruz et al., 2018).

^c in GRACIOUS, composition, crystallinity, particle size, particle shape, surface chemistry and specific surface area are considered to be “priority properties” ^prio; particularly in the context of REACH (Comandella et al., 2020).

^dOECD, Physical-chemical Decision Framework to Inform Decisions for Risk Assessment of Manufactured Nanomaterials (OECD, 2019).

^e “other information” involves crystal structure, solubility, magnetic properties, acidity/basicity, redox potential, catalysis photosensitivity, hydrophobicity, radical production capacity, etc.

^f “other information” involves ion release, solubility, shape, etc.