Tris(2,4-ditert-butylphenyl) phosphite

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:

2002-06-26, 2002-07-19

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.1 (Acute Toxicity for Fish)

Version / remarks:

EU Commission Directive 92/69/EEC, C1

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
Due to the low water solubility of the test Item, a supersaturated dispersion with a nominal concentration of 100 mg/L was prepared by weighing 501 mg of the test Item into 5000 mL test water. No auxiliary solvent or emulsifier was used. The test Item was mixed into the test water as homogeneously as possible by ultrasonic treatment for 15 minutes and by intense stirring for 96 hours at room temperature in the dark. The long stirring period of 96 hours was chosen to dissolve a maximum amount of the test Item In test water. Then, the supersaturated stock dispersion of the test item was filtered through a membrane filter (Schleicher & Schuell, Type NC45, pore size 0.45 µm) after the 96 hours stirring period just before the start of the test. The undiluted filtrate with the maximum concentration of dissolved test Item was used as the only test medium. The test medium was prepared just before introduction of the fish (= start of the test).

Test organisms (species):

Danio rerio (previous name: Brachydanio rerio)

Details on test organisms:

TEST ORGANISM
- Common name: zebra fish
- Source: Zoohaus Schaub, Liestal, Switzeriand
- Length at study initiation: 3.35 ± 0.07 cm
- Weight at study initiation: 0.37 ± 0.06 g
- Feeding during test: none

ACCLIMATION
- Acclimation period: 1 week
- Acclimation conditions: same as test
- Type and amount of food: commercial fish diet (TETRA MIN Hauptf utter, supplied by TETRA-Werke, Melle, Germany) until one day before the start of the test
- Health during acclimation: mortality rate In the test fish batch was lower than 5 % and all fish were healthy.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

96 h

Post exposure observation period:

none

Hardness:

2.5 mmol/L (= 250 mg/L) as CaCO3

Test temperature:

21 °C

pH:

7.9 - 8.0

Dissolved oxygen:

8.2 - 8.7 mg/L. The test water was aerated prior to the preparation of the test media until oxygen saturation was reached.

Nominal and measured concentrations:

100 mg/L(nominal) and below 100 µg/L (measured)

Details on test conditions:

TEST SYSTEM
- Test vessel: aquarium
- Type: open
- Material, size, headspace, fill volume: glass, filled with 5 L test medium
- Aeration: slight
- No. of organisms per vessel: 7
- No. of vessels per concentration: 1
- No. of vessels per control: 1
- Biomass loading rate: 1 g wet weight/L

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water:
Reconstituted water: analytical grade salts were dissolved in deionized water to obtain the following nominal concentrations:
CaCl2 X 2H2O: 2.0 mmol/L (= 294 mg/L)
MgS04 X 7H2O: 0.5mmol/L (=123 mg/L)
NaHCO3: 0.75 mmol/L (= 65 mg/L)
KCI: 0.075 mmol/L (= 5.8 mg/L)
Alkalinity: 0.8 mmol/L
Ratio of Ca : Mg = 4 : 1 (based on molarity)
Na:K = 10 : 1 (based on molarity)
The test water was aerated prior to the preparation of the test media until oxygen saturation was reached.

OTHER TEST CONDITIONS
- Adjustment of pH: none
- Photoperiod: 16 hours light and 8 hours darkness

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : the test fish were observed after approximately 3, 24, 48, 72, and 96 hours test duration for mortality and visible abnormalities. The water temperature, pH-values, and oxygen concentrations were measured at the start of the test and once every day during the test in the test medium and the control. At the same dates, the appearance of the test medium was recorded.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: one single dose

Key result

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

supersaturated dispersion

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

LC0

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

supersaturated dispersion

Basis for effect:

mortality (fish)

Details on results:

- Behavioural abnormalities: none
- Observations on body length and weight: not determined
- Other biological observations: none reported
- Mortality of control: none
- Other adverse effects control: none
- Abnormal responses: none
- Any observations that might cause a difference between measured and nominal values: none
- Effect concentrations exceeding solubility of substance in test medium: none

Validity criteria fulfilled:

yes

Description of key information

Tris(2,4-di-tert-butylphenyl)phosphite is with high probability acutely not harmful to fish.

Additional information

A static limit test was performed according to the OECD guideline 203 using a water-accommodated fraction approach [Ciba, 2002]. The nominal test concentration was 100 mg/L. Analysis of the test solution showed that the concentration was below the analytical detection limit of 100 µg/L. No mortalities or other abnormalities were seen in fish exposed to the test solution for 96 hours. Hence, the 96-hour LC0 was determined to be higher than the loading rate of at least 100 mg/L.