[nitrilotris(methylene)]trisphosphonic acid, ammonium salt

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1995-03-24 to 1995-03-26

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study but without GLP or analysis of exposure concentrations

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION

- Method: The test media were prepared by direct addition to, and dispersion in, the dilution water

- Controls: Dilution water

Test organisms (species):

Daphnia magna

Details on test organisms:

No data

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

270 mg/L as CaCO3

Test temperature:

21 degrees C

pH:

no data

Dissolved oxygen:

Air saturation at the start of the test

Salinity:

not applicable

Nominal and measured concentrations:

Nominal concentrations: 0 (Control), 1.0, 1.8, 3.2, 5.6, 10, 18, 32, 56 and 100 mg/L

Details on test conditions:

TEST SYSTEM

- Volume: 250 mL containing 200 mL of test medium

- Aeration: none

- Renewal rate of test solution (frequency/flow rate): static

- No. of organisms per vessel: 10

- No. of vessels per concentration (replicates): 2

- No. of vessels per control (replicates): 2

- Biomass loading rate: 1 daphnid/20 mL of test medium


TEST MEDIUM / WATER PARAMETERS

- Source/preparation of dilution water: Reconstituted freshwater


EFFECT PARAMETERS MEASURED (with observation intervals if applicable): mobility after 24 and 48 hours

TEST CONCENTRATIONS

- Spacing factor for test concentrations: 1.8

- Range finding study: yes

- Test concentrations: 0 (Control), 0.1, 1.0, 10 and 100 mg/L

- Results used to determine the conditions for the definitive study: No effect at 10 mg/L, 100% effect at 100 mg/L

Reference substance (positive control):

no

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

66 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 56-77 mg/L

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

18 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

- Immobilisation in control: 0%

Reported statistics and error estimates:

The data were analysed to determine EC50 and NOEC values using the methods of Thompson (1947).

Thompson, W.R. (1947). Bact. reviews, 11, pp. 115-145

Table 1. Test results

Nominal concentration (mg/L)	Mean percentage immobilisation after 24 hours	Mean percentage immobilisation after 48 hours
0 (Control)	0	0
1.0	0	0
1.8	0	0
3.2	0	0
5.6	0	0
10	0	0
18	0	0
32	0	5
56	0	25
100	0	95

Validity criteria fulfilled:

yes

Conclusions:

A 48-hour EC50 value of 66 mg/L and NOEC of 18 mg/L have been determined for the effects of the test substance on mobility of Daphnia magna.

Description of key information

One study is available with ATMP-xNH₄:

48-hour EC₅₀ 66 mg/L, Daphnia magna. This value is used for the purposes of Classification and Labelling and is reported in terms of the test material, rather than as ATMP active acid, as the ammonia drives the toxicity of the substance in the test.

Data have been read-across from ATMP-H:

48-hour LC₅₀ 94 mg active acid/L, Acartia tonsa, read-across from ATMP-H.

Ammonia: 96-hour LC₅₀ 0.16 mg NH₃-N/L, Hyalella azteca

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC50

Effect concentration:

66 mg/L

Fresh water invertebrates

Dose descriptor:

LC50

Remarks:

toxicity data for ammonia

Effect concentration:

0.16 mg/L

Marine water invertebrates

Marine water invertebrates

Dose descriptor:

LC50

Effect concentration:

94 mg/L

Additional information

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

The key study conducted with ATMP-xNH₄ reported an EC₅₀ value of 66 mg/L for the effects on Daphnia magna. This study clearly demonstrates that the ammonium salt is driving the toxicity of the substance because the toxicity of ATMP acid and sodium salts to aquatic invertebrates in the supporting studies alone are all >100 mg/L.

Several other supporting studies are available.

A 48-hour EC₅₀ value of 297 mg active acid/L was reported for the effects of ATMP-H on the mobility of Daphnia magna. The pH of the test media ranged between 2.0 and 8.2, so the mortalities observed could be an effect of the pH of the test medium, rather than a reflection of true toxicity. The study was assigned Reliability 2 (Monsanto, 1981).

A 48-hour LC₅₀ value of 94 mg active acid/L was reported for the mortality of the marine invertebrate, Acartia tonsa in a Reliability 2 study (Zeneca, 1995a).

Henkel (1972) reports a 24-hour EC₅₀ value of 375 mg/L for the toxicity of ATMP-H to the mobility of Daphnia magna however, little information on the study methodology was reported and so the study was assigned a Reliability score of 4.

A 48-hour EC₅₀ value of 833 mg active acid/L has been reported for the effects of ATMP-H to the mobility of Daphnia magna however, the documentation was insufficient for a reliability assessment and the study was assigned Reliability 4 accordingly (Monsanto, 1976a).

A 48-hour EC₅₀ value of 883 mg active acid/L was reported for the effects of ATMP-H on the mobility of Daphnia magna. Documentation was insufficient for a reliability assessment and so the study was assigned a Reliability score of 4 (Monsanto, 1976b).

Three reliable studies have been conducted by EG&G, reporting EC₅₀ values of (48h) 4574, (48h) 11400 and (96h) 201 mg/L for the effects of ATMP-H on Palaemonetes pugio, Chironomus tentans and Crassostrea sp., respectively (EG&G 1976a, 1976b and 1977, respectively).

A review article reported a 24-hour EC₀ of 300 mg/L for the effects of ATMP-H on the mobility of Daphnia magna however, the documentation of the methodology was not sufficient and the study was assigned a Reliability score of 4 (Schoberl & Huber, 1988).

Lastly, a 48-hour LC₅₀ value of >291 mg active acid/L was reported for the effects of ATMP-xNa on the mortality of Acartia tonsa (TNO, 1997).

Ammonia: A 96-hour LC₅₀ value of 0.16 mg NH₃-N/L has been determined for the effects of unionised ammonia on Hyalella azteca, reported in 'Environment Agency Proposed EQS for Water Framework Directive Annex VIII Substances: Ammonia (unionised) 2007' (EA, 2007).

ATMP-xNH₄ will dissociate as it is released into the aquatic environment and it is therefore necessary to assess the hazard properties and derive PNECs for ATMP and ammonia separately.

For hazard classification, ATMP-xNH₄ has been assessed based on the available aquatic data for the whole 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, 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.