Tris(2,4-ditert-butylphenyl) phosphite

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1992-08-24, 1992-12-03

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: 87/302/EEC page 89-94 Algal growth inhibition test

Deviations:

no

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

yes

Remarks:

Initial cell density 1.1 x 10e4 cells/mL. The measured concentration at the three highest concentrations tested are 74, 72, and 75 % of the nominal value. Response variables and yield were not calculated.

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 1.23, 3.7, 11, 33, and 100 mg test substance/L from day 0 and day 3
- Sampling method: Composite samples (about 150 mL per concentration and control) of each test concentration were drawn by mixing identical volumes of the test solutions taken from the approximate center of the test vessels. They were taken immediately before exposure and after 72 hours exposure and kept at - 18 °C to - 22 °C until analysis.
- Sample storage conditions before analysis: frozen at -18 to -22 °C

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: stock solution: 2.00 g test substance and 18 g water containing 0.4 % polyoxy-ethylene-sorbitan-monooleate (TWEEN80) were mixed together, by means of a marble mill during about 72 h. 1 g of this blend was mixed and made up to 1000 mL with water. Calculated amounts of the stock solution to produce the desired test concentrations were given into the water and were homogeneously distributed. The algae were then transferred into the flasks.
- Chemical name of vehicle: polyoxy-ethylene-sorbitan-monooleate (TWEEN80)
- Concentration of vehicle in test medium: 0.4 % (stock solution)

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: green algae
- Strain: SAG 86.81
- Source (laboratory, culture collection): Collection of algae cultures Pflanzenphysiologisches Institut University Nikolausberger Weg 18 D-3400 Gottngen Germany

ACCLIMATION
- Acclimation period: 3 days
- Culturing media and conditions: same as test
- Any deformed or abnormal cells observed: none reported

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Post exposure observation period:

none

Test temperature:

23 ± 1 °C

pH:

7.8 - 10.0

Nominal and measured concentrations:

1.23, 3.7, 11, 33, and 100 mg test substance/L (nominal) and 1.1, 3.1, 8.1, 23.8, and 75.2 mg test substance/L (measured)
The measured concentration at the three highest concentrations tested are 74, 72 and 75% of the nominal value, respectively.

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer flasks, stoppered with aluminium caps, on Lab-shaker
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: 100 mL, filled with 50 mL solution
- Initial cells density: 11000 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6
- No. of vessels per vehicle control (replicates): 3

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Sterile test conditions: no
- Adjustment of pH: none
- Photoperiod: continuous
- Light intensity and quality: cold white fluorescent light, 120 µE/m2 sec ± 20 % (approx. 8000 lux)

EFFECT PARAMETERS MEASURED:
- Determination of cell concentrations: counting chamber, at 24, 48, and 72 hours
- Chlorophyll measurement: none
- Other: pH (0 and 72 hours) and temperature (continuously)

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3

Reference substance (positive control):

no

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 75.2 mg/L

Conc. based on:

test mat.

Remarks:

Values calculated based on measured end concentrations.

Basis for effect:

cell number

Remarks on result:

other: 95 % CL: none

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

75.2 mg/L

Conc. based on:

test mat.

Remarks:

Values observed based on measured end concentrations.

Basis for effect:

cell number

Remarks on result:

other: 5 % level

Details on results:

- Exponential growth in the control: yes
- Observation of abnormalities: none reported
- Any stimulation of growth found in any treatment: none
- Any observations that might cause a difference between measured and nominal values: none reported
- Effect concentrations exceeding solubility of substance in test medium: none reported

Validity criteria fulfilled:

yes

Description of key information

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

Additional information

The toxicity of tris(2,4-di-tert-butylphenyl)phosphite on the green algae Scenedesmus subspicatus was measured in a test performed according to the OECD guideline 201 [Ciba, 1992]. Tween 80 was used as solubiliser. The test concentrations was analytically monitored. No effect observed up to the highest test concentration of about 75.2 mg/L.