[nitrilotris(methylene)]trisphosphonic acid, ammonium salt

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Reference 1

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 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

Analytical monitoring:

not specified

Vehicle:

no

Test organisms (species):

activated sludge

Test type:

not specified

Water media type:

not specified

Limit test:

no

Total exposure duration:

30 d

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 the test substance 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, 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.

Reference 2

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.

Reference 3

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 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:

Results determined in Sapromat test, derived from comparison of biochemical oxygen demand

GLP compliance:

not specified

Analytical monitoring:

not specified

Vehicle:

no

Test organisms (species):

activated sludge

Details on inoculum:

Klaeranlage-Muenchen-Grosslappen

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

5 d

Remarks on exposure duration:

Whilst the exposure duration is not explicitly stated, BOD5 values are quoted and so it is deduced that the exposure period is at least 5 days duration.

Post exposure observation period:

Not reported

Hardness:

Not reported

Test temperature:

Not reported

pH:

Not reported

Dissolved oxygen:

Not reported

Salinity:

Not reported

Nominal and measured concentrations:

Not reported

Details on test conditions:

Test concentration series: 1, 5, 10, 50 and 100 mg/L

Reference substance (positive control):

no

Duration:

5 d

Dose descriptor:

EC0

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Validity criteria fulfilled:

not applicable

Conclusions:

A non-standard study of activated sludge respiration inhibition determined that the top concentration of 100 mg/L did not cause inhibition. The result is considered reliable.

Reference 4

Endpoint:

activated sludge respiration inhibition testing

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Justification for type of information:

Please refer to Annex 3 of the CSR and IUCLID Section 13 for justification of read-across within the ATMP category.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

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:

5 d

Dose descriptor:

EC0

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Description of key information

One study is available for ATMP-xNH₄, and data have been read-across from ATMP-H as a weight of evidence approach.

(WOE) 30-day NOEC 200 mg/L activated sludge respiration inhibition (non-standard test), read-across from ATMP-H

(WOE) 5-day EC₀ ≥ 100 mg/L based on inhibition of respiration of activated sludge (non-standard test), read-across from ATMP-H

(WOE) 3-hour EC₅₀ >1000 mg/L based on inhibition of respiration of activated sludge (OECD 209).

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

200 mg/L

Additional information

ATMP-xNH₄ will dissociate when it is released into aqueous environments to yield ATMP and ammonia. One study is available for ATMP ammonium salts and further data are read-across from ATMP-H.

Three reliability 2 studies have been included as a weight of evidence approach to assess the toxicity of ATMP-xNH4 to microorganisms.

In a reliable, activated sludge respiration inhibition test conducted with an ammonium salt of ATMP, a 3-hour EC₅₀ value of >1000 mg/l was determined (Worth and Mead, 1995). The study was conducted in accordance with OECD Test Guideline 209.

In a reliable, non-standard respiration inhibition study, a 30-day NOEC value of 200 mg active acid/L was determined for the effects of ATMP-H on microorganisms (Henkel, 1972).

In a reliable, non-standard respiration inhibition study, a 5-day EC₀ value of ≥ 100 mg/L was determined for the effects of ATMP-H on microorganisms (Huber, 1975).

A supporting study is also read-across from ATMP-H, in which an EC₀ value of >250 mg/L has been determined for the effects on Pseudomonas putida. However, documentation was insufficient for assessment, therefore it has been assigned a reliability value of 4.

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.

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

ATMP-xNH₄ will dissociate when it is released into aqueous environments to yield ATMP and ammonia. ATMP and ammonia are therefore treated separately for the purposes of deriving PNEC_STP. The PNEC_STP for ammonia has been derived from the data presented here and in section 7.6 of the CSR. The PNEC_STP for ATMP has been determined using test data for ATMP-H and its salts. For hazard classification, ATMP-xNH₄ has been assessed based on the available aquatic data for the whole substance.

The acid, sodium, potassium and ammonium salts in the ATMP category are freely soluble in water. The ATMP anion can be considered fully dissociated from its sodium, potassium or ammonium cations when in dilute solution. Under any given conditions, the degree of ionisation of the ATMP 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 ATMP-H, ATMP.4Na, ATMP.7K or another salt of ATMP.

 

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

1. ATMP is present as ATMP-H or one of its ionised forms. The degree of ionisation depends upon the pH of the media and not whether ATMP (3-5K) salt, ATMP (3-5Na) salt, ATMP-H (acid form), or another salt was used for dosing.
2. Disassociated potassium, sodium or ammonium cations. The amount of potassium or sodium present depends on which salt was dosed.
3. It should also be noted that divalent and trivalent cations would preferentially replace the sodium or potassium ions. These would include calcium (Ca²⁺), magnesium (Mg²⁺) and iron (Fe³⁺). These cations are more strongly bound by ATMP than potassium, sodium and ammonium. This could result in ATMP-dication (e.g. ATMP-Ca, ATMP-Mg) and ATMP-trication (e.g. ATMP-Fe) complexes being present in solution.

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