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Ecotoxicological information

Toxicity to microorganisms

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Endpoint:
toxicity to microorganisms, other
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
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:
toxicity to microorganisms, other
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
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.
Endpoint:
toxicity to microorganisms, other
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
secondary literature
Principles of method if other than guideline:
Method: other: DIN 38412
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
Nominal / measured:
nominal
Conc. based on:
other: active acid

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.

Description of key information

The available data provide a general weight of evidence of a lack of inhibition of micro-organisms at concentrations up to 200 mg/L.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:
200 mg/L

Additional information

A reliability 4 EC50 value of >2500 mg/l has been determined for the effects of DTPMP 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 acco rding 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 because they are structural analogues, have similar physicochemical properties and are not readily biodegradable.

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

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 present in 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.