Polyphosphoric acids, ammonium salts

Short-term toxicity to aquatic invertebrates

Description of key information

One key study exists on an analogous substance. This study had been conducted in accordance with a recommended guideline (OECD 202, EU Method C.2) and under the conditions of GLP. As such, no further testing is considered necessary

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

100 mg/L

Additional information

Exposure of Daphnia magna to diammonium hydrogenorthophosphate gave EC50 values based on the nominal test concentrations of greater than 100 mg/L. The No Observed Effect Concentration was 100 mg/L.

The acute toxicity of the test item to the freshwater fish rainbow trout (Oncorhynchus mykiss) has been investigated and based on the nominal test concentrations gave a 96-Hour LC50 of greater than 100 mg/L. The No Observed Effect Concentration was 100 mg/L.

Read-across in accordance with Annex XI, Section 1.5 of Regulation (EC) No. 1907/2006 (REACH) is justified on the following basis:

Polyphosphoric acids, ammonium salt (also known as ammonium polyphosphate) is a mixture of oligomeric species of ammonium phosphate. When analysed the substance appears to consist mainly of ammonium orthophosphates, ammonium diphosphate and ammonium triphosphate.

The proposed source chemical (diammonium hydrogenorthophosphate) has the following (EC number 231-987-8) is very soluble in water (> 10000 mg/L). In aqueous media soluble inorganic orthophosphates will dissociate to their ionic constituents; in this case ammonium and orthophosphate ions. The target chemical is also a highly soluble inorganic phosphate (>10000 mg/L). In aqueous media the oligomeric species of ammonium phosphate will dissociate to ammonium cations and pyrophosphate, pyrophosphate and triphosphate anions. The pyrophosphate and triphosphate anions are unstable in aqueous solutions with the degree of instability varying according to pH. In distilled water they will hydrolyse slowly via abiotic mechanisms to orthophosphate. In natural waters a number of different processes can occur; abiotic hydrolysis, biotic degradation (as a result of the action of phosphatases which cleave triphosphates and pyrophosphates into orthophosphate subunits) and assimilation by organisms in the water. Thus the target substance (ammonium polyphosphates) and the source substance (diammonium hydrogenorthophosphate) will be primarily absorbed as the same inorganic ions: ammonium and orthophosphate and are expected to behave in a similar manner under test conditions.

All (bio) transformation products of the source chemical are common to the target chemical and as such the data is considered to be adequate and reliable for use in the assessment of ammonium polyphosphate for the ecotoxicity hazard assessment.