Small enough to care and big enough to deliver

Definition of Nanomaterials

Nanomaterials are natural or manufactured substances with 50% or more of particles in the number size distribution containing particle sizes between 1 to 100 nm in at least one dimension.

Nanomaterials contain constituent particles:

  • in an unbound state
  • as an aggregate
  • as an agglomerate

Definition of Nanoforms

A substance may have one or more different nanoforms, based on differences in size, shape, surface treatment and functionalization as well as specific surface area. These parameters may influence the toxicological or ecotoxicological profile, exposure as well as behavior in the environment. Therefore, all the nanoforms of a substance have to be reported in the registration dossier.

Methods for the characterization of Nanomaterials and Nanoforms

  1. TEM: Transmission electron microscopy
  2. PSD: Particle Size Distribution
    Guidelines: OECD 110 or CIPAC MT 187
  3. BET (Brunauer–Emmett–Teller)
    Determination of the specific surface by gas adsorption
  4. Density: bulk density, tapped density or skeletal density
  5. Hydroxy groups acc. SEARS
    Determination of Specific Surface Area of Colloidal Silica by titration with sodium hydroxide
  6. Point of Zero Charge (physical state, when the electrical charge density on a surface is zero)
  7. REM = SEM
    Scanning electron microscopy
  8. XRD: X-ray diffraction
    Characterization of amorphous Nanoforms including quantification by Rietveld method

Determination of Physical-chemical properties

The following studies are recommended to describe Nanomaterials:

Physical-chemical properties
Norm Description

OECD 105

Water solubility

OECD 105

Water solubility for silica with Tyndall effect


Transformation – Dissolution Study for inorganic Nanomaterials

OECD 318

Dispersion Stability of Nanomaterials in Simulated Environmental Media

OECD 110

Particle Size Distribution (PSD), angular laser diffraction wet and dry




All studies for Nanomaterials are recommended to be performed as chronic studies and mostly under flow through conditions:

  1. Aquatic plant studies: Lemna OECD 221
  2. Invertebrates studies: Daphnia OECD 211
  3. Fish studies: OECD 210, OECD 212, OECD 215
  4. Earthworm studies: OECD 222
  5. Chironomus studies: OECD 218 and OECD 219


Since the Ames study (OECD 471) is not recommended for Nanomaterials, Genotoxicity/Mutagenicity shall be evaluated using one or more in vitro studies on mammalian cells:

  • OECD 473: In Vitro Mammalian Chromosome Aberration Test
  • OECD 487: In Vitro Mammalian Cell Micronucleus Test
  • OECD 490: In Vitro Mammalian Cell Gene Mutation Test: Mouse Lymphoma Assay
  • OECD 476: Hypoxanthine-guanine phosphoribosyl transferase Test: HPRT Test

Endocrine Properties

Level testing
Level 1 Literature data
Level 2 YES/YAS Assay and/or Steroidogenesis in vitro (OECD TG 456)
Level 3 Uterotrophic Assay (OECD TG 440)* and/or Hershberger Assay (OECD TG 441)*
Level 4 Fish Sexual Development Test (OECD 234) or
Fish Reproduction Partial Lifecycle Test or
Chironomus Toxicity Test (OECD 218-219) or
Daphnia magna Reproduction Test (OECD 211) or
Earthworm Reproduction Test (OECD 222) or
Sediment Water Lumbriculus Toxicity Test (OECD 225)
Level 5 Fish Life Cycle Test (Danio rerio)
*will be subcontracted

We would be happy to offer you the recommended studies.