Trisodium dihydrogen -N,N-[bis[2-[bis(carboxylatomethyl)amino]ethyl]]glycinate

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

26-30 May 1987

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Good quality study with analysis, however there is no certificate of analysis. The study was assigned a reliability score of 2 based on the water hardness of 350 mg/L which was outside of the preferred range of 10 - 250 mg/L CaCO3. The toxicity of the test substance is known to decrease with increasing water hardness.

Justification for type of information:

The source substance (DTPA 5K) and the target substance (DTPA 3Na) are the pentapotassium and trisodium salts of the same organic acid and are therefore structurally very similar. The source substance has a purity of 97.0%, but since the target material is > 99.9% pure and contains no detectable impurities, the extrapolation of acute oral toxicological properties from the source material to the target material is considered valid as a ‘worst case' scenario. The two substances are of comparable high water solubility. The source material short- term toxicity study was conducted according to OECD test guideline 203 and is considered reliable with restrictions (Category 2).

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Version / remarks:

Test water hardness slightly above recommended upper range limit

Deviations:

yes

Principles of method if other than guideline:

Recommended hardness of water: 10-250 mg/L CaCO3 test water hardness was 350 mg/l CaCO3. This is considered not to have had a significant effect on the results of the test.

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

Samples were taken after 0, 24 and 96 hours and analyses were conducted using a spectophotometer.

Details on test solutions:

Test solutions were prepared by direct dispersion in water, control and 1000 mg/L.

Dilutions were made in Laboratory tap water, dechlorinated by the addition of sodium
thiosulphate. Total hardness = 350 mg/l as CaCO,. This value is
slightly higher than the recommended range but is not considered to
have had any significant effects on the results of the test.

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Details on test organisms:

Rainbow trout (salmo gairdneri)
Source: Parkwood trout farm, Wigmore, kent, United Kingdom.
The stock of fish was held since 16 February 1987 and was acclimatised to test conditions from 19 - 26 May 1987.
Temperature: 14 ± 1ºC
Mortalities: 0%
Medication: none
Fish were fed daily with commercial trout pellets, but feeding was discontinued 24h prior to the test.
Mean standard length = 4.8 cm (SD = 0.3 cm), mean weight = 1.77 g (SD = 0.33 g), no data on age of fish.

Test type:

semi-static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

96 h

Post exposure observation period:

no

Hardness:

350 mg/L CaCO3

Test temperature:

14 ºC

pH:

7.2-7.8

Dissolved oxygen:

9.6-9.7 mg O2/L

Salinity:

no data

Nominal and measured concentrations:

nomimal concentrations: 0 and 1000 mg/L
analyses shoed concentrations to be between 104-127% of the nominal concentration. On average the concentration is within the 80-120% of the
nominal concentration and therfore the reported concentation is indeed 1000 mg/L.

Details on test conditions:

There was a daily renewal of test media to ensure stability of the test concentrations.

The lighting was controlled at 16h light- 8 h darkness cycle.
Test vessels: Glass aquaria holding 40L of test media. 1 test concentration in duplicate, plus 1 control (20 animals per test concentration).
Fish were placed at random in prepared test media, loading 0.45 g bodyweight/L.
Aeration via narrow bore glass tubes.

Criteria of death: absence of (i) respiratory movement and (ii) response to a physical stimulation.

Reference substance (positive control):

no

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

1 000 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Details on results:

highest tested concentrations of 1000 mg/L caused no mortality at all.

Results with reference substance (positive control):

no reference substance tested

Sublethal observations / clinical signs:

no mortality occured in this test

Validity criteria fulfilled:

yes

Conclusions:

Good quality study, however no certifcate of analysis or detailed description of the substance compositionis given, therefore the substance identity
is not sufficient.

Executive summary:

Test Substance: Glycine N-N Bis[2-[Bis(carboxymethyl)amine]ethyl]-pentapotassium salt

Test Species: Rainbow trout (Salmo Gairdneri)

Test type: Acute toxicity 96 h LC50

Test conditions: Semi-static test conditions accordi ng to OECD Guideline No. 203 referenced and EEC Directive 67/584 annex V

C.1 as publishec in 84/449/EEC

RESULTS:

LC50 (3, 6, 24, 48, 72 and 96h) > 1000 mg/L

Reference 2

Endpoint:

short-term toxicity to fish

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

The source substance (DTPA 5K) and the target substance (DTPA 3Na) are the pentapotassium and trisodium salts of the same organic acid (Diethylenetriaminepentaacetic acid) and are therefore structurally very similar. The two substances have high water solubility and would be dissociated in the aquatic environment. The trisodium salt is manufactured by the addition of an appropriate molar ratio of sodium hydroxide to the parent acid to give a neutral solution. The target substance is pH 7.5 +/ 0.5) in solution which is comparable to the test conditions used for the short-term fish toxicity test with the penta potassium salt (pH 7.2-7.8). The common organic acid moiety has a chelating mode of action and would be expected to exert long-term, non-specific adverse, systemic effects by the sequestration of essential metal ions, rather than acute toxicity. The counter ions would have no significance influence on the toxicities of the two substances. The extrapolation of short-term aquatic toxicity potential from the source to the target substance is therefore considered valid.

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

1 000 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Conclusions:

The 96hour LC50 of DTPA trisodium salt to fish is predicted to be in excess of 1000 mg/l.

Description of key information

Using a read-across approach from a study conducted on the structural analogue DTPA penta potassium salt, the EC50 of DTPA trisodium salt to fish (Salmo gairdneri) is predicted to be at least 1000 mg/L (on stoichiometric basis). The two substances are structurally very similar, particularly when ionised in the aqueous environment. Moreover, the fish acute toxicity study of DTPA penta potassium salt was undertaken at a pH (7.2-7.8), comparable to the neutral pH of the test substance.

 

 

 

 

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