Triisobutyl phosphate

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:

other information

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

documentation insufficient for assessment

Remarks:

analytical verification of the test substance is missing, not performed according to GLP and OECD guidelines,

Qualifier:

according to guideline

Guideline:

other: DIN 38412, Part 11

GLP compliance:

no

Analytical monitoring:

not specified

Vehicle:

yes

Details on test solutions:

Cremophor

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: water flea
- Source: Bundesgesundheitsamt Berlin, Germany
- Method of breeding: single breeding in 100 mL beaker

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Test temperature:

21 °C

pH:

7.2 - 7.6

Dissolved oxygen:

8.1 - 8.4 mg/L

Nominal and measured concentrations:

Test concentrations (nominal): 0.58, 1.0, 1.8, 3.2, 5.8, 10, 18, 32, 58 and 100 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 50 mL glass beaker
- Fill volume: 20 mL
- No. of organisms per vessel: 5
- No. of vessels per concentration: 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: according to DIN 38412, Part 11
- Ca/mg ratio: 5/1
- Conductivity: 658 µS/cm

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Duration:

48 h

Dose descriptor:

EC0

Effect conc.:

5.8 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

11 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95% CL 9 - 12 mg/L

Duration:

48 h

Dose descriptor:

EC100

Effect conc.:

18 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Results with reference substance (positive control):

EC50 (24h): 1.1 mg/L potassium dichromate

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Version / remarks:

2004

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: 18200055
- Expiration date of the lot/batch: 30 June 2020
- Purity: 98.3%

Analytical monitoring:

yes

Details on sampling:

Each concentration and the control were analytically verified in the fresh media at the start of exposure solution (0 hours) as well as in the aged at the end of the exposure (48 hours). At the start of the exposure (0 hours), three samples per concentration level and control were taken after preparation of all concentration levels and analyzed. At the end of the exposure (48 hours), three samples of the 48-hours old media per concentration level and control were taken directly from the test vessels.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: A stock solution was prepared by adding an appropriate amount of the test item (100 mg/L) to dilution water. The stock solution and a further 4 test item concentrations were prepared by diluting the stock solution accordingly.
- Evidence of undissolved material (e.g. precipitate, surface film, etc.): no

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: water flea
- Strain/clone: 5
- Age at study initiation (mean and range, SD): < 24 h
- Method of breeding: In glass vessels (2 - 3 L capacity) with approximately 1.8 L culture medium, at 20 +- 2 °C, in an incubator, 16 hours illumination, light intensity of max. 1500 lx
- Source: Institut für Wasser-, Boden- und Lufthygiene (WaBoLu), Berlin, Germany
- Feeding during test : none

ACCLIMATION
- Acclimation period: continuous culturing at the test facility
- Acclimation conditions (same as test or not): same
- Type and amount of food: mix of unicellular green algae, e.g. Pseudokirchneriella subcapitata and Desmodesmus subspicatus, ad libitum
- Feeding frequency: 5 times per week

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Test temperature:

18 – 22 °C

Nominal and measured concentrations:

Nominal: 6.25, 12.5, 25.0, 50.0 and 100 mg/L
Measured (test inition): 6.47, 13.1, 27.2, 50.9 and 108 mg/L
Measured (48h): 5.93, 11.3, 23.3, 45.3 and 92.6 mg/L
Measured > 80% nominal

Details on test conditions:

TEST SYSTEM
- Test vessel: glass beakers (4 (ID) x 7 (H) cm), 50 mL capacity, loosely covered with watch glasses
- Volume of solution: 20 mL
- Aeration: no
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Elendt M4 medium
- Culture medium different from test medium: no
- Intervals of water quality measurement: At the start of the exposure (0 hours), the water quality parameters of the fresh media (i.e. pH-value, dissolved oxygen concentration) were measured in one additional replicate (without daphnids) per concentration level and control. At the end of the exposure (48 hours), the water quality parameters of the old media were measured in one appropriate replicate (containing daphnids) per concentration level and control. The replicate with the highest immobilization rate per concentration level and control was measured.

OTHER TEST CONDITIONS
- Photoperiod: 16h light
- Light intensity: Diffuse light, light intensity of max. 1500 lx

EFFECT PARAMETERS MEASURED : Immobility was recorded after 24 and 48h exposure time.


- Adjustment of pH:
- Photoperiod:
- Light intensity:

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :

VEHICLE CONTROL PERFORMED: yes/no

RANGE-FINDING STUDY
- Test concentrations:
- Results used to determine the conditions for the definitive study:

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

24 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: analytically verified

Details on results:

- Behavioural abnormalities: none
- Other biological observations: none
- Mortality of control: no
- Abnormal responses: no
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: no

Results with reference substance (positive control):

- Results with reference substance valid? yes
- Relevant effect levels: 24h-EC50 = 2.03 mg/L
- validity range: 0.6 - 2.4 mg/L, acc. to AQS P 9/2 (02/2000); clone 5:

Validity criteria fulfilled:

yes

Conclusions:

The test substance showed a 48h-EC50 of 24 mg/L and thus, to be harmful to aquatic invertebrates.

Description of key information

EC50(48h) = 24 mg/L (nominal, analytically verified) for immobilisation of Daphnia magna (OECD 202)

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

24 mg/L

Additional information

Two studies are available investigating the short-term toxicity of triisubutyl phosphate to aquatic invertebrates. However, one of the studies (BASF 1989) was considered to be not reliable due to methodological shortcomings (missing analytical verification of test concentrations, not performed according to GLP and current OECD guidelines). Thus, a new test was performed according to current quality criteria. This key study was performed according to GLP and OECD giudeline 202 using Daphnia magna as test organism (Herrmann 2019). Analytical verification of the test concentrations at the beginning and the end of the test showed > 80% of nominal at any measurement. No mortality was observed in the control. The 48h-EC50 is determined to be 24 mg/L based on nominal concentrations.