Registration Dossier

Physical & Chemical properties

Endpoint summary

Administrative data

Description of key information

The test substance (Zirconium praseodymium silicon zircon, CAS 68187-15-5, EC 269-075-7) is an inorganic, yellow, odourless, powder.


- Melting point > 1000 °C.


- relative density 4.47.


- Particle size distribution: D50 = 9.6 µm, D90 = 21.8 µm, D10 = 3.3 µm


- Dustiness:


total: 44.61 mg/g


MMAD= 22.79 µm, GSD= 3.83


Fractional deposition in human respiratory tract: Head (ET): 48.1 %, Tracheobronchial (TB): 0.8 %, Pulmonary (PU): 0.9 %


- The transformation/dissolution


The dissolved concentrations of Si at a 1 mg/l loading after 7 and 28 days and at a 100mg/L loading after 7 days were below the LOD (0.07 µg/L) and therefore not determinable.


The dissolved concentrations of zirconium and praseodymium at a 100 mg/l loading after 7 days were 0.16 µg/L and 86.25µg/L, respectively.


The dissolved concentrations of zirconium and praseodymium at a 1 mg/l loading after 7 days were 0.17 µg/L and 2.1 µg/L, respectively.


The dissolved concentrations of zirconium and praseodymium at a 1 mg/l loading after 28 days were < LOD (0.08 µg/L) and 0.79 µg/L, respectively.

Additional information