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Short-term toxicity to aquatic invertebrates

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Reference
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1988-12-12, 1988-12-14
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
no GLP
Qualifier:
according to guideline
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Version / remarks:
1984
Deviations:
yes
Remarks:
Study period 24 hours. Test substance above limit of solubility in water. No analytic determination of test substance concentration
GLP compliance:
no
Analytical monitoring:
no
Vehicle:
yes
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: stock solution: 2.0 g test substance and 8 mg alkylphenol-poiyglykol-ether were mixed with and made up to 2000 ml with water. Calculated amounts of stock solution to produce the desired test concentrations were given into the water and were homogeneously distributed. The daphnia were then transfered into the beakers.
- Chemical name of vehicle: alkylphenol-poiyglykol-ether
- Concentration of vehicle in test medium: 4 mg/L (stock solution)
- Evidence of undissolved material: A slight deposit was observed at conc. 32-1000 mg/L (nominal) after 24 h exposure.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: water flea
- Strain: Straus 1820
- Age at study initiation: 0 - 24 h
- Method of breeding: 24 hours before the start of the test reproductive daphnia are separated from the young by sieving all individuals through a 800 µm seive. This operation is repeated immediately before the start of the test
- Feeding during test: none

ACCLIMATION
Cultures of daphnia are maintained in glass vessels containing approx. 2.5 L of reconstituted water at 20 ± 1 °C (water is renewed partially thrice weekly). At each renewal the daphnia are fed a suspension of green algae (Scenedesmus subspicatus) supplemented by a suspension of TETRAMIN-extract in such quantities that the food is consumed after 24h.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
24 h
Post exposure observation period:
none
Hardness:
240 mg CaCO3/L
Test temperature:
20 ± 1 °C
pH:
7.5 - 7.8
Dissolved oxygen:
95 - 99 %
Nominal and measured concentrations:
32, 58, 100, 180, 320, 580, and 1000 mg/L (nominal)
Details on test conditions:
TEST SYSTEM
- Test vessel: beakers covered with watch glasses
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: filled with 100 mL solution
- Aeration: none
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per vehicle control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reconstituted water produced by dissolving:
65 mg NaHCO3
294 mg CaCl2 · 2 H2O
123 mg MgSO4 · 7 H2O
6 mg KCl
in 1000 mL bidistilled water.
The water was aerated with clean air for at least 24h before use.

OTHER TEST CONDITIONS
- Adjustment of pH: none
- Photoperiod: 16 hours daily
- Light intensity: Fluorescent light, approx. 2000 lux

EFFECT PARAMETERS MEASURED: mobility at 0 and 24 hours; oxygen, pH, temperature daily

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 1.8
Reference substance (positive control):
no
Duration:
24 h
Dose descriptor:
EC50
Remarks:
calculated
Effect conc.:
510 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 95 % CL: 450-590 mg/L
Duration:
24 h
Dose descriptor:
EC50
Remarks:
graphically determined
Effect conc.:
520 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
24 h
Dose descriptor:
EC0
Remarks:
in test
Effect conc.:
180 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
24 h
Dose descriptor:
EC100
Remarks:
in test
Effect conc.:
1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
- Behavioural abnormalities: none reported
- Observations on body length and weight: not determined
- Other biological observations: none reported
- Mortality of control: none reported
- Other adverse effects control: none reported
- Abnormal responses: none reported
- Effect concentrations exceeding solubility of substance in test medium: A slight deposit was observed at conc. 32-1000 mg/L (nominal) after 24 h exposure.
Reported statistics and error estimates:
The EC50-values were calculated according to SPEARMAN-KAERBER in: D.J. Finney, 524-530, London (1964).
EC-values were graphically determined on gausso-logarithmic probability paper.

Description of key information

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

Key value for chemical safety assessment

Additional information

A 24 hour static toxicity study withDaphnia magna carried out according to OECD guideline 202 [Ciba, 1988].The exposure concentrations were greatly in excess of the water solubility and the concentrations were not measured. The test solutions were prepared with alkylphenol polyglycol ether as solubiliser.

No increase in the number of immobile daphnids compared with controls were evident in groups exposed to 32, 58, 100 or 180 mg/l. An increase in the number of immobile daphnids compared at higher concentrations may be caused by physical effects of undissolved test materials. Overall, it can be concluded that the results do indicate that the substance is not acutely toxic to Daphnia magna at the limit of water solubility.