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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

One key study exists. This study (Clarke N, 2011) has been conducted on an analogous substance (iron orthophosphate),in compliance with current OECD Guidelines (OECD 209) and to GLP. This study is therefore considered to be scientifically justified for use as a key study under Regulation (EC) No. 1907/2006.

Key value for chemical safety assessment

EC50 or LC50 for microorganisms:
1 000 mg/L
EC10, LC10 or NOEC for microorganisms:
1 000 mg/L

Additional information

This study is submitted for the following reasons:

In accordance with Regulation (EC) No. 1907/2006 (REACH) Annex XI, section 2 testing for a specific endpoint may be omitted if it is technically not possible to conduct the study as a consequence of the properties of the substance. Tetrairon tris(pyrophosphate) is an insoluble inorganic material and is not considered to be bioavailable in aquatic environments. This is demonstrated by the fact that iron is often added to effluents containing soluble phosphates in order to remove phosphorus (via making the phosphate insoluble) and prevent eutrophication in water bodies.

As a result of the physicochemical properties, administration of precise and consistent dose levels is not considered to be possible and as such aquatic toxicity testing is not considered to be technically possible. As such a study on a similar substance (iron orthophosphate is submitted). Read-across is justified on the following basis:

 Both substances are relatively insoluble inorganic ferric (Fe3+) compounds. In conditions where the substances have limited solubility/bioavailability; ionisation to the Fe cation and the orthophosphate cation (iron orthophosphate) or pyrophosphate cation (tetrairon tris(pyrophosphate) will occur. In biological systems (i.e. in the presence of alkaline phosphatase) the pyrophosphate will be broken down into orthophosphate. It is considered that the Fe3+ cation is of most relevance when considering the toxicity of the test material and as iron orthophosphate is slightly more soluble this substance is a good candidate for read-across.