Cordierite (Mg2[Al4O3(SiO3)5])

Bioaccumulation: aquatic / sediment

Link to relevant study record(s)

Reference

Endpoint:

bioaccumulation in aquatic species: fish

Type of information:

other: Assessment based on the bioavailability of the substance and the bioavailability of the ions that will release to the aquatic environment.

Adequacy of study:

weight of evidence

Study period:

2017

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Assessment based on the bioavailability of the substance and the bioavailability of the ions that will release to the aquatic environment.

Qualifier:

no guideline followed

Principles of method if other than guideline:

Assessment based on the bioavailability of the substance and the bioavailability of the ions that will release to the aquatic environment.

GLP compliance:

no

Remarks on result:

other: Assessment based on the bioavailability of the substance and the bioavailability of the ions that will release to the aquatic environment.

Validity criteria fulfilled:

not applicable

Conclusions:

As a result of this assessment and in accordance with Guidance R.7c: Endpoint specific guidance (Version 2.0 - November 2014), the registered substance is not likely to bioaccumulate in aquatic species.

Executive summary:

In accordance with Guidance R.7c: Endpoint specific guidance (Version 2.0 - November 2014), inorganic substances are requiring special considerations regarding testing and exposure. The octanol-water partition coefficient (Kow) is not relevant in order to assess the bioaccumulation of an inorganic substance as the purpose of the Kow is to determine the distribution of non-polar organic compounds between water and natural solids (e.g. sediments) or organisms. Therefore, the bioaccumulation of the registered substance in aquatic species will depend on its bioavailability and the bioavailability of the ions that the substance will release to the aquatic environment.

The substance is a synthetic mineral with a crystalline structure having a theoretical empirical formula of Mg2Al4Si5O18. Due to the particle size of the substance, it cannot be absorbed as such by the aquatic species and must first be dissolved for the absorption process to occur. The water solubility performed on the registered substance according to OECD TG 105 showed that aluminium, silicon, and magnesium ions were released to water. However, the high lattice energy of the structure implies that the dissolution of the substance would require conditions far more extreme than those the substance will experience in the aquatic environment. The hydrolysis assessment of the substance concluded that it was hydrolytically stable under normal conditions. The dissolved ions identified during the water solubility study are considered to be surface ions not interlinked in the crystalline structure of the substance. As a result only a limited quantity of aluminium, silicon, and magnesium ions will be released by the substance to the aquatic environment, which will be available for direct uptake by aquatic organisms. These ions are naturally occurring in all environmental compartments and their concentrations will be below the natural background levels.

According to Guidance R.7c: Endpoint specific guidance (Version 2.0 - November 2014), aquatic species will absorb some of these dissolved ions to meet their metabolic requirements. However it is not expected that their release will affect significantly the concentration of these dissolved ions in the natural environment and therefore their “natural” bioavailability to aquatic species.

In the EU concentrations of magnesium in water range from 0.05 to 230 mg/l depending on the area with a median value of 6.02 mg/l (FOREGS Geochemical Atlas of Europe, 2005). Concentrations of aluminium in water range from <0.1 to 812 µg/l depending on the area with a median value of 17.7 µg/l (FOREGS Geochemical Atlas of Europe, 2005). Concentrations of silicon in water range from <0.1 to 72 mg/l depending on the area with a median value of 8.03 mg/l (FOREGS Geochemical Atlas of Europe, 2005). The concentrations of silicon and aluminium are expected to be limited by the formation of Si-Al complexes in water (FOREGS Geochemical Atlas of Europe, 2005).

Description of key information

In accordance with Guidance R.7c: Endpoint specific guidance (Version 2.0 - November 2014), the registered substance is not likely to bioaccumulate in aquatic species.