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Ecotoxicological information

Toxicity to microorganisms

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Endpoint:
toxicity to microorganisms, other
Remarks:
non-standard study for the effects of the tested substance on sewage gas production volume
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The study was well documented and meets generally accepted scientific principles, but was not conducted in compliance with GLP.
Qualifier:
no guideline followed
Principles of method if other than guideline:
Non-quantitative study of effect of increasing concentration of test substance on the sewage treatment process
GLP compliance:
not specified
Vehicle:
no
Test organisms (species):
activated sludge
Test type:
not specified
Water media type:
not specified
Limit test:
no
Duration:
30 d
Dose descriptor:
NOEC
Effect conc.:
200 mg/L
Nominal / measured:
nominal
Conc. based on:
not specified
Basis for effect:
other: sewage gas production volume
Duration:
30 d
Dose descriptor:
LOEC
Effect conc.:
500 mg/L
Nominal / measured:
nominal
Conc. based on:
not specified
Basis for effect:
other: sewage gas volume reduced and fermentation delayed
Details on results:
At 50 mg/L Dequest 2000 showed no effects.
At 100 and 200 mg/L the start of fermentation was delayed, but constant gas volume was achieved in the same period as in the control.
At 500 mg/L Dequest 2000, the system was strongly disturbed, as indicated by a late beginning of fermentation, and greatly reduced sewage gas production volume.
Conclusions:
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 result of a lack of effects on respiration up to 200 mg/L provides reliable evidence.
Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The study was conducted according to an appropriate OECD test guideline. It was not compliant with GLP.
Qualifier:
according to guideline
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
GLP compliance:
no
Analytical monitoring:
not specified
Vehicle:
no
Test organisms (species):
activated sludge of a predominantly domestic sewage
Details on inoculum:
Source: The aeration stage of Severn Trent Water PLC Sewage Treatment Plant, Belper, Derbyshire. The sample was maintained at 21 °C with continuous aeration and used on the day of collection. The pH 6.8 and the suspended solids level equal to 4.1 g/l prior to use.
Test type:
not specified
Water media type:
not specified
Limit test:
yes
Total exposure duration:
3 h
Reference substance (positive control):
yes
Remarks:
3,5-dichlorophenol
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Results with reference substance (positive control):
3.2 mg/l 1% inhibition
32 mg/l 79% inhibition

Concentration (mg/l)

O2consumption rate

(mg O2/l/min)

% Inhibition

respiration rate

Control (R1)

0.40

-

Control (R2)

0.37

-

 

Test substance 1000 (R1)

0.37

11

Test substance 1000 (R2)

0.37

11

Test substance 1000 (R3)

0.38

8

 

Reference 3.2

0.36

13

Reference 32

0.06

86
Validity criteria fulfilled:
yes
Conclusions:
An EC50 value of >1000mg/l was determined in a reliable study conducted according to an appropriate test protocol. Not conducted according to GLP.
Endpoint:
toxicity to microorganisms, other
Remarks:
non-standard study for the effects of the tested substance on the bioluminescence of the bacterium Photobacterium phosphoreum
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
4 (not assignable)
Principles of method if other than guideline:
Method: other
GLP compliance:
not specified
Analytical monitoring:
not specified
Test organisms (species):
Photobacterium phosphoreum
Total exposure duration:
30 min
Details on test conditions:
Type: aquatic
Duration:
30 min
Dose descriptor:
EC0
Effect conc.:
> 2 500 mg/L

Result expressed as nominal concentration. Properties of the
test substance and evidence from other studies (where
concentrations were measured) indicate that nominal and
measured concentrations are likely to be in good agreement.

Endpoint:
toxicity to microorganisms, other
Remarks:
non-standard study for the effects of the tested substance on sewage gas production volume
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The study was well documented and meets generally accepted scientific principles, but was not conducted in compliance with GLP.
Qualifier:
no guideline followed
Principles of method if other than guideline:
Non-quantitative study of effect of increasing concentration of test substance on the sewage treatment process
GLP compliance:
not specified
Vehicle:
no
Test organisms (species):
activated sludge
Test type:
not specified
Water media type:
not specified
Limit test:
no
Duration:
30 d
Dose descriptor:
NOEC
Effect conc.:
200 mg/L
Nominal / measured:
nominal
Conc. based on:
not specified
Basis for effect:
other: sewage gas production volume
Duration:
30 d
Dose descriptor:
LOEC
Effect conc.:
500 mg/L
Nominal / measured:
nominal
Conc. based on:
not specified
Basis for effect:
other: sewage gas volume reduced and fermentation delayed
Details on results:
At 50 mg/L HEDP showed no effects.
At 100 and 200 mg/L the start of fermentation was delayed, but constant gas volume was achieved in the same period as in the control.
At 500 mg/L HEDP, the system was strongly disturbed, as indicated by a late beginning of fermentation, and greatly reduced sewage gas production volume.
Conclusions:
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 result of a lack of effects on respiration up to 200 mg/L provides reliable evidence.

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.

ATMP-xNH4:

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

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.

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-xNH4 will dissociate when it is released into aqueous environments to yield DTPMP and ammonia. DTPMP and ammonia are therefore treated separately for the purposes of deriving PNECSTP. The PNECSTP for ammonia has been derived from the data presented here and in section 7.6 of the CSR. The PNECSTP for DTPMP has been determined using test data for DTPMP-H and read-across from structurally analogous substances. For hazard classification, DTPMP-xNH4 has been assessed based on the available aquatic data for the whole substance (based on read-across data from the ammonium salt of ATMP, a structurally analogous substance).

The influence of the ammonium salt is discussed in IUCLID Section 6.0 Ecotoxicological Information and Section 7.0 of the CSR.

The acid and salts in the DTPMP category are freely soluble in water and, therefore, the DTPMP anion is fully dissociated from its cations when in solution. Under any given conditions, the degree of ionisation of the DTPMP species is determined by the pH of the solution. At a specific pH, the degree of ionisation is the same regardless of whether the starting material was DTPMP-H, DTPMP (1-3Na), DTPMP (5-7Na), DTPMP (4-8K), DTPMP (xNH4) or another salt of DTPMP.

 

Therefore, when a salt of DTPMP is introduced into test media or the environment, the following is present (separately):

  1. DTPMP is present as DTPMP-H or one of its ionised forms. The degree of ionisation depends upon the pH of the media and not whether DTPMP-H, DTPMP (1-3Na), DTPMP (5-7Na), DTPMP (4-8K), DTPMP (xNH4), or another salt was used for testing.
  2. Disassociated ammonium, potassium or sodium cations. The amount of ammonium, potassium or sodium present depends on which salt was added.
  3. Divalent and trivalent cations have much higher stability constants for binding with DTPMP than the sodium, potassium or ammonium ions so would preferentially replace them. These ions include calcium (Ca2+), magnesium (Mg2+) and iron (Fe3+). Therefore, the presence of these in the environment or in biological fluids or from dietary sources would result in the formation of DTPMP-dication (e.g. DTPMP-Ca, DTPMP-Mg) and DTPMP-trication (e.g. DTPMP-Fe) complexes in solution, irrespective of the starting substance/test material.

In this context, for the purpose of this assessment, read-across of data within the DTPMP Category is considered to be valid.