Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

Pyrochlore:

The overall chemical and physiological properties of pyrochlore are principally characterised by a degree of inertness because of the specific synthetic process (calcination at high temperatures, approximately 1000°C), rendering the substance to be of a unique, stable crystalline structure in which the majority of atoms are tightly bound and not prone to dissolution in environmental and physiological media. This has been shown in transformation/dissolution testing for antimony, in which dissolved Sb concentrations were below 27 µg/L (after 7 days at a loading of 0.1g/L) and 2 µg/L (after 28 days at a loading of 1 mg/L); thus implying a solubility of < 0.03% of antimony. Hence, Sb can be considered as not bioavailable and is not regarded concerning toxicological and environmental effects.

On the other hand, lead dissolution levels were much higher (>2.9 mg/L at a loading of 100 mg/L after 7 days at pH 6; 105 µg/L at a loading of 1 mg/L after 28 days at pH 6) and therefore have to be regarded concerning toxicological and environmental aspects. No substance-specific data on the toxicity of pyrochlore are available, so that instead read-across to lead oxide and sparingly soluble lead compounds was conducted

Lead:

From the literature overview, the following bioaccumulation/bioconcentration factors have been derived for Pb:    

 - Aquatic compartment

Bioaccumulation/bioconcentration factors in freshwater: 1,553 L/kg

- Soil compartment

Bioaccumulation/bioconcentration factors in soil: 0.39 kg/kg (dry weight)