Triisobutyl phosphate

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:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

other: DIN 38412, Part 15

GLP compliance:

no

Analytical monitoring:

not specified

Vehicle:

not specified

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: directly added

Test organisms (species):

Leuciscus idus

Details on test organisms:

TEST ORGANISM
- Common name: orfe
- Source: Eggers, Hohenwesttedt, Germany
- Length at study initiation: 6.1 cm
- Weight at study initiation: 1.7 g

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Hardness:

total hardness: 0.9 - 1.4 mmoL/L

Test temperature:

20 +/-1°C

pH:

7.7 - 8.0

Dissolved oxygen:

7.1 - 8.0 mg/L

Nominal and measured concentrations:

Test concentrations (nominal): 0, 14.7, 17.8, 21.5 and 26.1 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: aquaria (30 X 22 X 24 cm)
- Fill volume: 10 liter
- No. of organisms per vessel: 10
- No. of vessels per concentration: 1
- No. of vessels per control: 1

Reference substance (positive control):

yes

Remarks:

potassium cyanide

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

17.8 - 21.5 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Results with reference substance (positive control):

LC50 (48h) ca. 28 mg/L potassium cyanide

Validity criteria fulfilled:

not specified

Reference 2

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Test procedure in accordance with national standards

Qualifier:

according to guideline

Guideline:

other: Japanese Industrial Standard K 0102-1974

GLP compliance:

no

Analytical monitoring:

not specified

Vehicle:

not specified

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Directly added

Test organisms (species):

Oryzias latipes

Details on test organisms:

TEST ORGANISM
- Common name: rice fish
- Source: Nippon Dobutsu Jakuhin KK. (Japan Pet Drugs Co. LDT) 4-37-9, Nishi Shinkoiwa Katsushika-Ku, Tokyo
- Length at study initiation: 2.6 cm
- Weight at study initiation: 178 mg

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

total hardness: 1.3 - 2.6 mmoL/L

Test temperature:

25 +/- 2 °C

pH:

7.9 - 8.5

Dissolved oxygen:

7.8 - 8.6 mg/L

Nominal and measured concentrations:

Test concentrations (nominal): 0, 10, 20, 40 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: glas aquaria (30cm X 22cm X 24cm)
- Fill volume: 10 Liter
- No. of organisms per vessel: 10
- No. of vessels per concentration: 1
- No. of vessels per control: 1

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: dechlorinate tape water

Reference substance (positive control):

not specified

Key result

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

20 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% CL 14 - 26 mg/L

Details on results:

48h-LC5: 10 mg/L (95% CL 4-14 mg/L)
48h-LC95: 39 mg/L (95% CL 28-102 mg/L)

Validity criteria fulfilled:

yes

Reference 3

Endpoint:

short-term toxicity to fish

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 203 (Fish, Acute Toxicity Test)

Version / remarks:

1992

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 Jul 2020
- Purity: 98.3%

Analytical monitoring:

yes

Details on sampling:

Samples were taken in the fresh media at the start of exposure and at renewal (0 and 48 hours) and in the 48-hours old media after 48 and 96 hours.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: An appropriate volume of the test item was pipetted directly into a test vessel filled with 10 L of dilution water. The test media were mixed with an ultraturrax (1 min, 17000 rpm). This procedure was repeated for the water renewal interval after 48 hours. The control dilution water was treated accordingly.

Test organisms (species):

Danio rerio (previous name: Brachydanio rerio)

Details on test organisms:

TEST ORGANISM
- Common name: zebra fish
- Source: All fish used in the test were gained at Noack Laboratorien GmbH from a single brood stock (supplier: Umweltbundesamt, Schichauweg 58, D-12307 Berlin, supply date: 07/2007)
- Maintenance of the brood fish: Holding was performed at the test facility at 23 ± 2 °C and diffuse light (7 – 750 Lux, natural photoperiod). The water was changed at least once per week. The dissolved oxygen concentration was more than 80% of the air saturation value.

ACCLIMATION
- Acclimation period: at least 12 days
- Acclimation conditions (same as test or not): same
- Type and amount of food during acclimation: 4% of the fish body weight per feeding day
- Feeding frequency during acclimation: 3 times per week
- Health during acclimation (any mortality observed): no

Test type:

semi-static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

96 h

Hardness:

62 mg/L as CaCO3

Test temperature:

24 +- 1 °C

pH:

6.0 – 8.5

Dissolved oxygen:

Not less than 60% of air saturation value.

Salinity:

-

Conductivity:

-

Nominal and measured concentrations:

Nominal: 15 mg/L
Measured (geom. mean): 12.6 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 13 L glass aquaria with 10L test solution
- Aeration: gentle aeration was provided
- Renewal rate of test solution (frequency/flow rate): after two days
- No. of organisms per vessel: 1
- No. of vessels per concentration (replicates): 7
- No. of vessels per control (replicates): 7
- Biomass loading rate: 0.067g fish/L

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Tap water of local origin was used for holding. The water was filtered on activated charcoal and aerated for at least 24 h to remove chlorine.
- Alkalinity: 0.4 mmol/L
- Culture medium different from test medium: no
- Intervals of water quality measurement: The pH-value, temperature and oxygen saturation were measured in all test vessels at test start and end of exposure as well as daily and after renewal of the test media from fresh and old test media.
Total hardness was determined at the start of the exposure out of the control. During the test the water temperature was recorded once per hour with a data logger. The light intensity on the surface of the test aquaria was measured at the start of the exposure. The solution appearance and behavior were observed daily before and after renewal.

OTHER TEST CONDITIONS :
- Photoperiod: A photoperiod (light / dark cycle: 16 / 8 h) was maintained during exposure
- Light intensity: 540 - 1000 lux

EFFECT PARAMETERS MEASURED : Mortality was recorded daily.

TEST CONCENTRATIONS
- Results used to determine the conditions for the definitive study: 15 mg/L were tested as a threshold concentration in a limit test. The selection of the test concentration is based on the derivation of a threshold concentration (TC) from the results of an alga toxicity test ErC50 (0-72 h) = 14.3 mg/L (nominal test item concentration; Herrmann 2019) and a daphnia acute immobilization test EC50 (0-48 h) 24.0 mg/L (nominal test item concentration; Herrmann 2019).

Reference substance (positive control):

no

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 12.6 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

LC0

Effect conc.:

>= 12.6 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Details on results:

No mortality was observed in the treatment and the control throughout the test period.

Sublethal observations / clinical signs:

At the start of the exposure and at renewal (48 hours) the measured concentrations were 92% and 87% of the nominal value. The measured concentrations in the old media (48 and 96 hours) were 73 and 84% of the nominaltest item concentration (see illustration).

Validity criteria fulfilled:

yes

Conclusions:

None of the 7 fish died during the test. It was therefore concluded that the limit test provides sufficient evidence, that the toxicity of the test item to fish is not higher than to algae and that the ErC50 determined in algae is sufficiently protective for aquatic species.

Description of key information

LC50(96h) > 12.6 mg/L (measured, geom. mean) for mortality of Danio rerio (OECD 203)

Additional information

Three studies are available investigating the short-term toxicity of triisubutyl phosphate to aquatic invertebrates. However, the two older studies were considered to be not sufficiently reliable due to methodological shortcomings. Thus, a new test was performed according to current quality criteria. This key study was performed according to GLP and OECD giudeline 203 using Danio rerio as test organism in a limit test (Herrmann 2019). The effect level is given based on the geometric mean measured concentration of Triisobutylphosphate, since the measured concentrations deviated by more than 20% from the nominal value. The threshold concentration of the test item at the concentration level of 12.6 mg/L was found to have no lethal effects on zebrafish (LC0 = 12.6 mg test item/L). Thus, a 96h-LC50 is determined to be > 12.6 mg/L. Sublethal effects were recorded in all fish exposed to the test item, indicating that the tested concentration is close to the effect threshold. Since the measured concentrations in the freshly prepared test solutions were lower than the nominal value, the geometric mean measured concentration in this limit test were unexpectedly only 88% of the ErC50 value in algae (14.3 mg/L), on which the limit concentration of this fish toxicity test was based. However, a deviation of 12% is clearly within the variability of aquatic toxicity results. The test guidelines allow a deviation of +- 20% from the nominal concentrations. None of the 7 fish died during the test. It was therefore concluded that the limit test provides sufficient evidence, that the toxicity of the test item to fish is not higher than to algae and that the ErC50 determined in algae is sufficiently protective for aquatic species. This concusion is supported by the two supporting studies which should LC50 values above the 72h-EC50 determined for algae.

In acute fish tests according to Japanese industrial standard and according to German national standard (DIN 38412), the LC50 values ranged between 17.8 and 21.5 mg/L[BASF AG, 1978].