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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

No study of microbial inhibition is available for the DTPMP ammonium salt. The available data provide a general weight of evidence of a lack of inhibition of micro-organisms at concentrations up to ca. 200 mg/L. Furthermore a reliable ASRI study is available for an ammonium salt of a structurally analogous phosphonate (EC50 >1000 mg/L).

Key value for chemical safety assessment

Additional information

The assessment of the toxicity of the substance to microrganisms for the purposes of hazard classification is based on the available test result determined with the analogous substance ATMP-xNH4 (CAS 34274-28-7).

 

DTPMP-xNH4 will dissociate when it is released into aqueous environments to yield DTPMP and ammonia. DTPMP and ammonia are therefore be treated separately for the purposes of deriving PNECstp for sewage treatment plant.

ATMP-xNH4

A 30-minute EC50 value of >1000 mg/L has been obtained in an activated sludge respiration (ASRI) test with ATMP-xNH4.

Ammonia:

Typical levels of free ammonia in municipal WWTPs range from ca. 12-50 mg/l in the WWTP collection system (Lehr, Jay; Keeley, Jack; Lehr, Janet Water Encyclopedia, Volumes 1-5. (section 1.4.49). John Wiley & Sons.). A NOEC of >50 mg/l, can therefore be predicted for ammonia toxicity to microorganisms.

DTPMP:

A reliability 4 EC50 value of >2500 mg/l has been determined for the effects of DTPMP acid on the bioluminescence of the bacterium Photobacterium phosphoreum (Grohmann and Horstmann 1989).

A non-standard study of effects on sewage treatment plant micro-organisms was conducted according to generally accepted scientific principles but lacks detail in the study report. The study reports a lack of effects on respiration for 30 days up to 200 mg/L with ATMP and HEDP.

The data can be directly read across to DTPMP-xNa because they are structural analogues and because the effects may be due acidic effects.

All these studies have been used as weight of evidence to determine the low toxicity of DTPMP-xNa to micro-organism toxicity. The data from ATMP and HEDP has been used to determine the PNEC being non-limit results.