Trihydrogen tris[P,P-dioctyl diphosphato(2-)-O'',O''''](propan-2-olato)titanate(3-), branched and linear

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

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

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP-compliant, guideline study with some deviations.

Justification for type of information:

Read across valid as the substnace tested is also titanate complex with alkylphosphate, degrading in water to form simple alcohols including 2-propanol and phosphate esters.

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

yes

Principles of method if other than guideline:

Due to the rapid hydrolysis of the test substance on contact with water, the original substance was not analysed in test solutions and it could not be verified that substances were maintained within 80% of nominal concentrations.

GLP compliance:

yes

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
No data reported.

Analytical monitoring:

no

Details on sampling:

Growth measurements were made at 0, 24, 48 and 72 hours.

Vehicle:

yes

Details on test solutions:

A master culture was used to innoculate the sterile nutrient medium. The inoculated solution was incubated at 24°C and stirred continuously using an orbital shaker under continuous illumination of c. 7000 lux. Auxillary solvent was used to dissolve 200 mg of test substance. This was diluted to required concentrations and added to algal suspensions.

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

Species: CCAP 276/20. Holding conditions: on orbital shaker under continuous illumination for 72 hours (OECD guideline 201). Temperature: 24 +/-1°C. Source: Culture Centre of Algae and Protozoa c/o Freshwater Biological Association, Cumbria, UK.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Post exposure observation period:

No data reported.

Hardness:

No data reported.

Test temperature:

24 +/- 1°C

pH:

The pH ranged from 7.9-8.0 at test initiation and from 7.9 to 9.1 at test termination.

Dissolved oxygen:

Not aerated. Orbital shaker was used to maintain the gaseous exchange.

Salinity:

Freshwater

Nominal and measured concentrations:

Nominal concentrations: 0.125, 0.25, 0.5, 1.0 and 2.0 mg/L.

Details on test conditions:

Vessels: 100 ml of test solution was placed in loosely stoppered 250 ml glass flasks. Number of concentrations: 5 test solutions, 1 solvent control (100 ml/L auxillary solvent), 1 blank control. Number of replicates per concentration: 3. Illumination: continuous at c. 700 lux.

Reference substance (positive control):

no

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

1.45 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

ca. 2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.125 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

All solutions were visually inspected at test termination and no abnormalities were detected.

Results with reference substance (positive control):

Mean cell density of control: 1.06E-05 cells/ml at test initiation and 4.86E+06 cells/ml at test termination. Mean cell density of solvent control: 1.17E+05 at test initiation and 4.93E+06 cells/ml at test termination.

Reported statistics and error estimates:

The index of growth was taken from the area under each curve. Comparison of the area under the test curve with the area under the solvent curve was used to determine the inhibition of growth at each concentration. The straight section of the graph was used to determine the average maximum growth rate for each solution.

Validity criteria fulfilled:

no

Remarks:

Due to the rapid hydrolysis of the test substance on contact with water, the original substance was not analysed in test solutions and it could not be verified that substances were maintained within 80% of nominal concentrations.

Conclusions:

The 72 hour EC50 for biomass is 1.45 mg/L. The 24-48 hour EC50 for growth rate is c. 2 mg/L. The 72 hour NOEC is 0.125 mg/L.

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

20-23 September 1990

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP-compliant, guideline study with some deviations.

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

yes

Remarks:

Due to the rapid hydrolysis of the test substance on contact with water, the original substance was not analysed in test solutions and it could not be verified that substances were maintained within 80% of nominal concentrations.

Principles of method if other than guideline:

Due to the rapid hydrolysis of the test substance on contact with water, the original substance was not analysed in test solutions and it could not be verified that substances were maintained within 80% of nominal concentrations.

GLP compliance:

yes

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
No data reported.

Analytical monitoring:

no

Details on sampling:

Growth measurements were made at 0, 24, 48 and 72 hours.

Vehicle:

yes

Details on test solutions:

A master culture was used to innoculate the sterile nutrient medium. The inoculated solution was incubated at 24°C and stirred continuously using an orbital shaker under continuous illumination of c. 7000 lux. Auxillary solvent was used to dissolve 200 mg of test substance. This was diluted to required concentrations and added to algal suspensions.

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

Species: CCAP 276/20. Holding conditions: on orbital shaker under continuous illumination for 72 hours (OECD guideline 201). Temperature: 24 +/-1°C. Source: Culture Centre of Algae and Protozoa c/o Freshwater Biological Association, Cumbria, UK.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Post exposure observation period:

No data reported.

Hardness:

No data reported.

Test temperature:

24 +/- 1°C

pH:

The pH ranged from 7.9-8.0 at test initiation and from 7.9 to 9.1 at test termination.

Dissolved oxygen:

Not aerated. Orbital shaker was used to maintain the gaseous exchange.

Salinity:

Freshwater

Nominal and measured concentrations:

Nominal concentrations: 0.125, 0.25, 0.5, 1.0 and 2.0 mg/L.

Details on test conditions:

Vessels: 100 ml of test solution was placed in loosely stoppered 250 ml glass flasks. Number of concentrations: 5 test solutions, 1 solvent control (100 ml/L auxillary solvent), 1 blank control. Number of replicates per concentration: 3. Illumination: continuous at c. 700 lux.

Reference substance (positive control):

no

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

1.45 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

ca. 2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.125 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

All solutions were visually inspected at test termination and no abnormalities were detected.

Results with reference substance (positive control):

Mean cell density of control: 1.06E-05 cells/ml at test initiation and 4.86E+06 cells/ml at test termination. Mean cell density of solvent control: 1.17E+05 at test initiation and 4.93E+06 cells/ml at test termination.

Reported statistics and error estimates:

The index of growth was taken from the area under each curve. Comparison of the area under the test curve with the area under the solvent curve was used to determine the inhibition of growth at each concentration. The straight section of the graph was used to determine the average maximum growth rate for each solution.

Validity criteria fulfilled:

no

Remarks:

Due to the rapid hydrolysis of the test substance on contact with water, the original substance was not analysed in test solutions and it could not be verified that substances were maintained within 80% of nominal concentrations.

Conclusions:

The 72 hour EC50 for biomass is 1.45 mg/L. The 24-48 hour EC50 for growth rate is c. 2 mg/L. The 72 hour NOEC is 0.125 mg/L.

Executive summary:

Douglas (1991) is a GLP-compliant, acute toxicity study on algae following OECD guideline 201. Due to the rapid hydrolysis of the test substance on contact with water, the original substance was not analysed in test solutions and it could not be verified that substances were maintained within 80% of nominal concentrations. The vessels were loosely stoppered to prevent evaporation and the study is considered reliable and suitable for use for this endpoint.

Description of key information

No study was conducted on the target substance. Read-across from structural analogue, Titanium butyl phosphate, is valid in that both substances are hydrolytically unstable and forms simple alcohols, including 2-propanol, and phosphate esters.

Based on the results of the structural analogue, the 72 hour EC50 for biomass is 1.45 mg/L. The 24-48 hour EC50 for growth rate is c. 2 mg/L. The 72 hour NOEC is 0.125 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

1.45 mg/L

EC10 or NOEC for freshwater algae:

0.125 mg/L