Sodium salts of [[(phosphonomethyl)imino]bis[ethane-2,1-diylnitrilobis(methylene)]]tetrakisphosphonic acid (5-7 Na:1)

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Reference 1

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:

Please refer to Annex 4 of the CSR and IUCLID Section 13 for justification of read-across within the DTPMP category.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

ca. 180 - ca. 252 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

6 435 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

mortality (fish)

Reference 2

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods with acceptable restrictions

Qualifier:

according to guideline

Guideline:

other: Methods for Acute Toxicity Tests with Fish, Macroinvertebrates, and Amphibians, USEPA, 1975

Deviations:

not specified

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Deviations:

not applicable

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION

- Method: the test substance was added directly into the each jar and mixed by stirring

- Controls: dilution water

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Details on test organisms:

TEST ORGANISM

- Common name: rainbow trout

- Source: Fish were obtained from a commercial fish hatchery in Washington, USA

- Length at study initiation (length definition, mean, range and SD): mean length of 33 mm.

- Weight at study initiation (mean and range, SD): mean wet weight of 1.9 grams at time of study

- Method of breeding: not reported

- Feeding during test: no


ACCLIMATION

- Acclimation period: 48 h

- Acclimation conditions (same as test or not): same as test

- Type and amount of food: animals were not fed during acclimation period

- Health during acclimation (any mortality observed): 0%

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Hardness:

35 mg/L CaCO3

Test temperature:

Water temperature was maintained at 12 deg C.

pH:

The pH of the test media was not reported. However a test was also conducted with Icatlurus punctatus in similar test conditions (higher temperature) and higher test concentrations, which reported a pH range of 7.0-8.2.

Dissolved oxygen:

50-99% saturation. The DO is below the recommended OECD level of 60%.

Nominal and measured concentrations:

Nominal test concentrations were 576, 432, 324, 252, and 180 mg/l as active acid. 

Details on test conditions:

TEST SYSTEM

- Test vessel: jars

- Material, size, headspace, fill volume: 19 L glass jars filled with 15L test medium

- Aeration: no

- No. of organisms per vessel: 10

- No. of vessels per concentration (replicates): 3

- No. of vessels per control (replicates): 3


TEST MEDIUM / WATER PARAMETERS

- Source/preparation of dilution water: well water

- Culture medium different from test medium: same

- Intervals of water quality measurement: DO and temperature were measured at 0, 48 and 96 hours in the highest, middle and lowest test concentration exposures and found to be acceptable. 


OTHER TEST CONDITIONS

- Adjustment of pH: not reported

- Photoperiod: not reported

- Light intensity: not reported

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : mortality every 24 h


TEST CONCENTRATIONS

- Spacing factor for test concentrations: 1.35

- Range finding study: yes, details not provided

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

ca. 180 - ca. 252 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

180 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

mortality (fish)

Reported statistics and error estimates:

LC50 values and 95% confidence intervals determined by regression analysis of concentrations expressed as logarithms and mortality expressed as probits.

Sublethal observations / clinical signs:

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.

Percentage mortality at each nominal test concentration:

Concentration mg/L	Mortality at 96 hours
Control	0
180	0
252	100
324	100
432	100
576	100

24 hr LC50: 252 (203-313) mg/L 
48 hr LC50: >180<252 mg/L

Validity criteria fulfilled:

no

Remarks:

DO was low

Conclusions:

A reliable 96 h LC50 value of ca. 180 - ca. 252 (ca. 216) mg/L has been determined for the effects of the test substance on the mortality of the freshwater fish Salmo gairdneri (new name: Oncorhynchus mykiss). The results should however be treated with caution as the DO levels decreased to 50%, while the concentrations at which this occurred are not reported. The result is considered valid as the controls mortality was 0%.

Reference 3

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods with acceptable restrictions

Qualifier:

according to guideline

Guideline:

other: Methods for Acute Toxicity Tests with Fish, Macroinvertebrates, and Amphibians, USEPA, 1975

Deviations:

not specified

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.1075 (Freshwater and Saltwater Fish Acute Toxicity Test)

Deviations:

not applicable

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION

- Method: appropriate amounts of test substance were directly added to the vessels

- Controls: dilution water only

Test organisms (species):

Cyprinodon variegatus

Details on test organisms:

TEST ORGANISM

- Common name: sheepshead minnow

- Source: collected from stocked ponds at the testing laboratory 

- Length at study initiation (length definition, mean, range and SD): 15-20 mm standard length

- Method of breeding: not reported


ACCLIMATION

- Acclimation period: a minimum of 7 days before testing

- Acclimation conditions (same as test or not): not reported (only "acclimation to laboratory conditions" reported)

- Type and amount of food: not reported

- Health during acclimation (any mortality observed): <1%

Test type:

static

Water media type:

saltwater

Limit test:

no

Total exposure duration:

96 h

Test temperature:

Water temperature was maintained at 20 +/- 1 degree C.

pH:

The pH of the test media ranged between 6.7 and 8.3

Dissolved oxygen:

>= 58% saturation for all concentrations and control

Salinity:

25 parts per thousand

Nominal and measured concentrations:

Nominal test concentrations were 1000, 10000, 18000, 32000 and 56000 ml/l (ppm).

Details on test conditions:

TEST SYSTEM

- Test vessel: jars

- Type (delete if not applicable): open

- Material, size, headspace, fill volume: Testing was conducted in 19 litre uncovered glass jars containing 15 litres of test medium.

- Aeration: no

- No. of organisms per vessel: 10

- No. of vessels per concentration (replicates): 1

- No. of vessels per control (replicates): 1



TEST MEDIUM / WATER PARAMETERS

- Source/preparation of dilution water: Filtered natural sea water.

- Intervals of water quality measurement: DO and pH were measured during the study and remained within acceptable limits


OTHER TEST CONDITIONS

- Adjustment of pH: not reported

- Photoperiod: not reported

- Light intensity: not reported


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : mortality, every 24 h


TEST CONCENTRATIONS

- Spacing factor for test concentrations: 2 and 10

- Range finding study: not reported

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

6 435 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

mortality (fish)

Reported statistics and error estimates:

Test concentrations were converted to logarithms and corresponding percentage mortalities to probits. LC50 values were then determined by linear regression.

Sublethal observations / clinical signs:

Table 1. Mortality of fish during 96 h exposure.

Nominal concentration (u/l; ppm)	Mortality (%)
	24h	48h	96h
Control	0	0	0
1000	0	0	0
10 000	0	0	0
18 000	0	10	10
32 000	60	60	60
56 000	100	100	100

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.

24 hr LC50: 5377 mg/l (30,299 ppm)

48 hr LC50:

5377 mg/l (30,299 ppm)

96 hr LC50: 5377 mg/l (30,299 ppm)

The results reported have been corrected for active acid content (18%) and density (1.18).

Validity criteria fulfilled:

yes

Conclusions:

A reliable 96 h LC50 value of 6435 mg active acid/l has been determined for the effects of DTPMP acid towards the mortality of the marine fish Cyprinodon variegatus.

Description of key information

96 h LC₅₀ ca. 180 - ca. 252 mg active acid/L (read-across) Salmo gairdneri (new name: Oncorhynchus mykiss)

96 h LC₅₀ 6435 mg active acid/L (read-across) Cyprinodon variegatus

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Dose descriptor:

LC50

Effect concentration:

ca. 180 - ca. 252 mg/L

Marine water fish

Marine water fish

Dose descriptor:

LC50

Effect concentration:

6 435 mg/L

Additional information

Freshwater

Data on short term toxicity of DTPMP Na salts (5-7Na and 1-3Na) and DTPMP acid to freshwater fish are available, however since the data are related to active acid content and it is possible to freely read-across from DTPMP acid to the sodium salt and the lowest LC₅₀ value, based on is represented by data for the acid, have been read-across as the key study for this endpoint.

A reliable 96-hour LC₅₀ value of ca. 180 - ca. 252, (ca. 216 mg/L) has been determined for the effects of DTPMP-H on the mortality of the freshwater fish Salmo gairdneri (new name: Oncorhynchus mykiss) (EG&G 1976a). The dissolved oxygen levels decreased down to 50%, while the concentrations at which this occurred are not reported, the test is considered valid as the mortality in the controls was 0%. This is the lowest reliable LC₅₀ value and has been selected as key. The study was conducted on a neutralised form (pH 7) of DTPMP acid.

The results of tests conducted on DTPMP and its salts are directly comparable, because the substance will fully dissociate in solution and the ionisation state will depend only on the pH of the test medium. The counterion is not considered to contribute to effects in fish. At environmentally-relevant pH values, DTPMP will be ionised typically 6-8 times, and will form stable complexes with metal ions. Here, the values of ca. 180 - ca. 252 mg equivalent active salt/L may be directly read-across.

 

Other short-term toxicity studies for DTPMP Na salts (5-7Na and 1-3Na) reported freshwater LC₅₀ values in the range 1200 to 5372 mg active acid/L (Inveresk, 1982; Gledhill and Feijtel, 1992). These studies indicate the very low short-term toxicity of DTPMP towards fish.

Marine

No reliable data on short term toxicity of DTPMP Na salts to marine fish are available. However, a reliable 96 h LC₅₀ value of 6435 mg active acid/l has been determined for the effects of DTPMP acid towards the mortality of the marine fish Cyprinodon variegatus (EG&G 1976b). Here, the value of 6435 mg equivalent active acid/L may be directly read-across.

A disregarded study reported a 96h LC₅₀ of 350 mg active acid/L for the effects of DTPMP(5-7Na) to Scopthalamus maximus, however it was disregarded due to deviations in pH and lack of analytical monitoring (Opus Plus ltd, 2004).

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.