Sodium salts of [[(phosphonomethyl)imino]bis[ethane-2,1-diylnitrilobis(methylene)]]tetrakisphosphonic acid (1-3 Na:1)

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

other: Proposed ISO Guideline and PARCOM protocol

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION

- Method: direct dispersion into a stock solution

- Controls: only dilution water

Test organisms (species):

other: Acartia tonsa

Details on test organisms:

TEST ORGANISM

- Source: laboratory cultures.

- Age at study initiation (mean and range, SD): 6-8 days old

- Method of breeding: cultured under the standard conditions according to the relevant Standard Operating Procedure

- Feeding during test: no


ACCLIMATION

- Acclimation period: not reported

Test type:

static

Water media type:

saltwater

Limit test:

no

Total exposure duration:

48 h

Test temperature:

The test was carried out at 20 degrees C

pH:

The pH of the control and all test concentrations ranged between 7.2 and 8.0.

Dissolved oxygen:

greater than or equal to 7.1 mg/l

Salinity:

ca. 28 parts per thousand

Nominal and measured concentrations:

Nominal test concentrations were 56, 100, 180, 320 and 560 mg/l.

Details on test conditions:

TEST SYSTEM

- Test vessel: scintillation vial.

- Type (delete if not applicable): covered with a perspex plate

- Material, size, headspace, fill volume: 10 ml of test medium in a vial

- No. of organisms per vessel: Each vial contained one copepodite

- No. of vessels per concentration (replicates): 10 vials per treatment. 

- No. of vessels per control (replicates): 10 vials per treatment. 


TEST MEDIUM / WATER PARAMETERS

- Source/preparation of dilution water: Natural seawater passed through sand filter, a carbon filter and then a 5um membrane filter before use. Diluted with distilled water.

- Culture medium different from test medium: no

- Intervals of water quality measurement: The pH and oxygen concentrations were measured in control and test solutions at the beginning and the end of the test.


OTHER TEST CONDITIONS

- Adjustment of pH: not reported

- Photoperiod: 16 hour light-8 hour dark cycle. And two transition periods of 0.5 of twilight.

- Light intensity: not reported


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


TEST CONCENTRATIONS

- Spacing factor for test concentrations: 1.8

- Range finding study: yes, details not reported

Reference substance (positive control):

no

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

140 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 250 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

mobility

Reported statistics and error estimates:

NOEC determined as highest test concentration in which at least 90% of test organisms survived. LC50 calculation not required as 50% mortality was not achieved.

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.

Table 1. Mortality of Acartia tonsa during the 48 h exposure to DTPMP xNa.

Time (h)	Nominal concentration (mg/l)
	0	56	100	180	320	560
0	0	0	0	0	0	0
48	1/10	1/10	1/10	0/10	1/10	1/10

24 hr LC50: >1000 mg/l.
NOEC based on swimming behaviour/mobility.

Validity criteria fulfilled:

yes

Conclusions:

A reliable 48 h EC50 value of >250 mg active acid/l has been determined for the effects of DTPMP-xNa on the immobility of the marine copepod Acartia tonsa.

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

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

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION

- Method: a 500 ml stock solution was prepared by manual dispersion for each concentration. The solution was divided in triplicates beakers to provide replicate exposure treatments. Animals were assigned to each test beaker within 30 minutes after the compound was added.

- Controls: dilution water

Test organisms (species):

other: Chironomus tentans (aquatic insect)

Details on test organisms:

TEST ORGANISM

- Common name: midge

- Source: Midge larvae were obtained from in-house laboratory cultures at Bionomic Laboratory.

- Method of breeding: not reported

- Feeding during test: no



ACCLIMATION

- Acclimation period: not reported

- Acclimation conditions (same as test or not): same dilution water used in test

- Type and amount of food: not reported

- Health during acclimation (any mortality observed): not reported

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Test temperature:

21 degrees C +/- 1

Nominal and measured concentrations:

Nominal test concentrations were 25298, 18070, 13550, 10119, and 7589 mg/l as active acid.

Details on test conditions:

TEST SYSTEM

- Test vessel: beakers. The substrate consisted of white paper towel, homogenised in water with a Waring blender. The larvae used this for construction of dwelling tubes.

- Material, size, headspace, fill volume: 250 ml vessels containing 166 ml of test solution.

- Aeration: no

- Renewal rate of test solution (frequency/flow rate): not reported

- No. of organisms per vessel: 5

- 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, filtered through polyester fiber and sterilised with an ultraviolet steriliser to remove any micro-organisms prior to use in tests.

- Culture medium different from test medium: no

- Intervals of water quality measurement: not reported

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: approx. 1.35

- Range finding study: not reported

Reference substance (positive control):

no

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

7 589 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

mortality

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

9 910 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

mortality

Remarks on result:

other: (7200 - 13500)

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

15 100 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

mortality

Details on results:

- Mortality of control: 0%

- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: an maber colour which appeared to be proportional to the concentration was observed.

- Effect concentrations exceeding solubility of substance in test medium: no, the water solubility of the substance is 500 g/L

Reported statistics and error estimates:

 LC50 values and 95% confidence intervals determined by least squares regression analysis of concentrations expressed as logarithms and percentage mortalities expressed as probits

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.

Validity criteria fulfilled:

yes

Remarks:

for control mortality, water quality parameters not reported

Conclusions:

A reliable 48 h EC50 value of 9910 mg active acid/l has been determined for the effects of DTPMP acid on the mortality of the freshwater insect Chironomus tentans. The organisms is normally used for sediment tests, however since this is an aqueous exposure, the study has been considered in the freshwater aquatic assessment. No water quality data has been presented. Since there were no mortality in the controls and the pattern of mortality appeared regular it can be safely assumed that water quality parameters were within the norm.

Reference 3

Endpoint:

short-term toxicity to aquatic invertebrates

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:

48 h

Dose descriptor:

EC50

Effect conc.:

9 910 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

mortality

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 250 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

mobility

Description of key information

48-hour EC₅₀ 9910 mg active acid/L (read-across) Chironomus tentans

96-hour LC₅₀ >250 mg active acid/L (read-across) Acartia tonsa

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC50

Effect concentration:

9 910 mg/L

Marine water invertebrates

Marine water invertebrates

Dose descriptor:

LC50

Effect concentration:

> 250 mg/L

Additional information

Freshwater

A study is available indicating the short term toxicity of DTPMP(1-3Na) salts to Daphnia magna to be (48 -hour) EC₅₀ 158 mg active acid/L (Zeneca, 1995). An insufficient level of detail is reported in the test to determine whether pH had an effect on the mortality of the test organism and the study has been assigned reliability 4 by the reviewer.

However, a reliable 48 h EC₅₀ value of 9910 mg active acid/l has been determined for the effects of DTPMP acid on the mortality of the freshwater insect Chironomus tentans (EG&G, 1976). The organism is normally used for sediment tests, however since this is an aqueous exposure, the study has been considered in the freshwater aquatic assessment. No water quality data have been presented. Since there were no mortality in the controls and the pattern of mortality appeared regular it can be safely assumed that water quality parameters were within the norm.

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 invertebrates. At environmentally-relevant pH values, DTPMP will be ionised typically 6-8 times, and will form stable complexes with metal ions. Here, the value of 9910 mg equivalent active acid/L may be directly read-across.

 

Marine

A reliable 48-hour EC₅₀ value of >250 mg active acid/l has been determined for the effects of DTPMP(5-7Na) on the immobility of the marine copepod Acartia tonsa (TNO, 1997).

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-xK, 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-xK, 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.