tert-butylphenyldiphenyl phosphate (tBuTPP)

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2013

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Qualifier:

according to guideline

Guideline:

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

Qualifier:

according to guideline

Guideline:

other: ASTM Standard E729 96: Standard Guide for Conducting Acute Toxicity Tests on Test Materials with Fishes, Macroinvertebrates, and Amphibians

Principles of method if other than guideline:

not relevant

GLP compliance:

yes

Remarks:

Periodic analyses of water for potential contaminants were not performed according to GLP Standards, but were performed using a certified laboratory and standard US EPA analytical methods.

Analytical monitoring:

yes

Details on sampling:

- Concentrations: Samples were collected from each test chamber of each treatment and control group at the beginning of the test and at 48 and 96 h (± 1 h) to measure concentrations of the test substance based on the C4 and TPP components.
- Sampling method: The samples were collected at mid-depth, combined with an equal volume of acetonitrile, placed in glass vials and processed immediately for analysis.

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: A primary stock solution was prepared by mixing a calculated amount of test substance in tetrahydrofuran (THF) at a nominal concentration of 100 mg/L. A calculated amount of test substance was weighed into a tared glass beaker and the test substance was rinsed into the 100 mL glass volumetric flask. The flask was sonicated for approximately 1 minute to ensure that all test substance was dissolved in the solvent. The flask was brought to volume with THF and the solution was inverted at least 20 times to mix. The primary stock solution appeared clear and colorless, with no precipitate noted. A secondary stock solution at a nominal concentration of 15 mg/L was prepared by proportionally diluting an aliquot of the primary stock solution in THF to achieve the final volume of 500 mL. The secondary stock solution was inverted to mix and appeared clear and colorless, with no visible precipitate noted. Test chambers were filled with approximately 15 L of dilution water. Individual test solutions were prepared by adding aliquots of the secondary stock solution into 2000 mL glass volumetric flasks. The flasks were purged with nitrogen gas for approximately 180 minutes to evaporate the solvent. The flasks were filled with portion of the dilution water from the respective test chambers. The solutions were mixed overnight using Teflon™-lined stir bars and stir plates. After mixing, the content of the flasks were emptied into the appropriate test chambers, and the solutions were mixed using a top-down mixer for approximately 1 to 2 minutes.
- Controls: negative control solution was dilution water only
- Chemical name of vehicle: tetrahydrofuran
- Concentration of vehicle in test medium: The flasks were purged with nitrogen gas for approximately 180 minutes to evaporate the solvent.
- Evidence of undissolved material: test solutions in the test chambers appeared clear and colorless during the test, with no evidence of precipitation observed

Test organisms (species):

Pimephales promelas

Details on test organisms:

TEST ORGANISM
- Common name: fathead minnow
- Source: Chesapeake Cultures of Hayes, Virginia
- Age at tstudy initiation: juveniles
- Length at the end of the test: average 10 control fish: 2.6 cm (range: 2.5-2.9 cm)
- Weight at the end of the test: average wet weight 10 control fish (blotted dry): 0.16 g (range: 0.12-0.20 g)

ACCLIMATION
- Acclimation period: ≥ 14 days
- Acclimation conditions: water from the same source and at approximately the same temperature as used during the test
- Type and amount of food: a commercially-prepared diet supplied by Sera North America, Montgomeryville, Pennsylvania, supplemented with brine shrimp nauplii (Artemia sp.) supplied by Brine Shrimp Direct, Ogden, Utah
- Feeding frequency: daily except during periods of fasting prior to testing
- Health during acclimation: no signs of disease or stress

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Hardness:

132 mg/L as CaCO3 (dilution water at test initiation)

Test temperature:

22 ± 1ºC

pH:

8.3-8.4

Dissolved oxygen:

≥7.2 mg/L throughout the test

Nominal and measured concentrations:

- Nominal: negative control, 7.5, 15, 30, 60, 120 μg
- Measured (mean based on measured C4): < LOQ, 3.6, 6.6, 14, 34, 76 μg

Details on test conditions:

TEST MEDIUM / WATER PARAMETERS
- Alkalinity: 178 mg/L as CaCO3 (dilution water at test initiation)
- Conductivity: specific conductance: 362 μS/cm (diluation water at test initiation)

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 76 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

76 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Validity criteria fulfilled:

yes

Remarks:

(1) Mortality of fish in the negative control did not exceed 10% by the end of the test. (2) The dissolved oxygen concentration was ≥ 83% of the air-saturation value throughout the test.

Conclusions:

Fathead minnows (Pimephales promelas) were exposed for 96 h under static conditions to five mean measured concentrations of 3 G FF ranging from 3.6 to 76 µg/L. The 96 h LC50 value was >76 µg/L, the highest measured concentration tested. Fathead minnows exposed to 3 G FF at concentrations ≤76 µg/L, the highest measured concentration tested, appeared normal with no mortality or overt signs of toxicity. The 96 h no-mortality concentration and the NOEC were both 76 µg/L, the highest measured concentration tested.

Executive summary:

Measurement of test concentrations

Nominal concentrations selected for use in this study were 7.5, 15, 30, 60 and 120 µg/L formulated material. Test solutions in the test chambers at these nominal concentrations appeared clear and colorless during the test, with no evidence of precipitation observed.

The concentrations of C4 and TPP were monitored in the test solutions during the study. However, the concentrations of 3 G FF were determined based on measured C4 (76% of test substance) in the test solutions during the study and not based on the measured TPP (4% of test substance) in the test solutions. Measured concentrations of 3 G FF based on C4 in the samples ranged from approximately 24.6 to 135% of nominal. The measured concentrations of 3 G FF based on C4 in the test solution samples declined on Days 2 and 4 of the test. The low recoveries seen at the beginning of the test and the declines during the test were likely due to adsorption of the C4 component to the test chambers and/or the hydrophobicity of the material. However, the measured concentrations of TPP in the test solutions were consistent during the test. When measured concentrations of the samples were averaged, the mean measured test concentrations of 3 G FF based on measured C4 for this study were 3.6, 6.6, 14, 34 and 76 μg 3 G FF/L, representing 48, 44, 47, 57 and 63% of nominal concentrations, respectively. The results of the study were based on the mean measured concentrations of 3 G FF by monitoring C4 component of the test substance.

Observations and measurements

Water temperatures were within the 22 ± 1ºC range established for the test. Dissolved oxygen concentrations remained ≥7.2 mg/L throughout the test. Measurements of pH ranged from 8.3 to 8.4 during the test. Light intensity at test initiation was 533 lux at the surface of the water of one representative test chamber.

All fish in the negative control, 3.6, 6.6, 14, 34 and 76 µg 3 G FF/L treatment groups also appeared normal throughout the test, with no mortalities or overt signs of toxicity observed.

Conditions for the validity of the test

The study met the following criteria used to judge the validity of the test:

1. Mortality of fish in the negative control did not exceed 10% by the end of the test

2. The dissolved oxygen concentration was ≥ 83% of the air-saturation value throughout the test

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

76 µg/L