reaction product of diphenylmethanediisocyanate, octylamine, 4-ethoxyaniline and ethylenediamine (1:0,37:1,53:0,05)

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:

1998-10-23 to 1999-02-15

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: No concentrations in excess of the water solubility limit of the test substance were tested. Due to the low solubility of the test substance in test water the following dosage was chosen: A supersaturated stock suspension of the test substance with a nominal concentration of 100 mg/L was prepared by weighing 100 mg of the test substance into 1000 mL test water. No auxiliary solvent or emulsifier was used. The test substance was mixed into the test water as homogeneously as possible by ultrasonic treatment for 15 minutes and intense stirring. The supersaturated stock suspension was stirred on a magnetic stirrer at room temperature in the dark over 26 hours. Due to the results of a pre-experiment no differences of dissolved amount of test substance in test water were determined after stirring periods between 2 and 48 hours. The stock suspension of the test substance was filtered through a cellulose-nitrate filter with a defined pore size of 0.2 µm just before the start of the test.

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: Scenedesmus subspicatus CHODAT
- Strain: 86.81 SAG
- Source: The algae were supplied by the "Sammlung von Algenkulturen, Pflanzenphysiologisches Institut der Universität Göttingen", D-37073 Göttingen, Germany
- Method of cultivation: The algae are cultivated in the laboratories of IBACON under standardised conditions according to the test guidelines.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Hardness:

Not specified

Test temperature:

23.1 - 23.5 °C

pH:

Not specified

Dissolved oxygen:

Not specified

Salinity:

Not applicable

Conductivity:

Not specified

Nominal and measured concentrations:

100 mg/L (nominal concentration)

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer flasks of 50 mL volume with 50 mL test medium
- Initial cells density: 10000 cells/L
- Control end cells density: 69.35 x 10E04 cells/mL
- No. of vessels per concentration: three replicates
- No. of vessels per control: six replicates

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- according to the guideline

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: continuous illumination
- Light intensity and quality: 8380 Lux

EFFECT PARAMETERS MEASURED:
- Determination of cell concentrations: Defined volumes of the algae suspensions from all replicates and from the blanks were sampled after 24, 48 and 72 hours of exposure, and were not be replaced. The cell densities in the samples were determined by spectrophotometrical measurement.

Reference substance (positive control):

no

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: growth rate/biomass

Details on results:

- Exponential growth in the control: yes
- Observation of abnormalities: no remarkable observations

Results with reference substance (positive control):

Positive control not performed.

Reported statistics and error estimates:

Not applicable (limit test).

Validity criteria fulfilled:

yes

Conclusions:

The test item shows no toxic effects up to a nominal concentration of 100 mg/L after 7h hours of exposure.

Executive summary:

A limit test was performed to demonstrate that the test substance has no toxic effect on algae up to the solubility limit of the test substance in the used test water. At all determinations the number of cells in the filtrate of the supersaturated stock suspension was slightly higher than in the control samples. Therefore, in the filtrate no significant reduction of growth on algal cells was determined compared to the control during the test period of 72 hours. The 72-hour NOEC was determined to be at least up to the solubility limit of the test substance in test water. The NOEC might even be higher than this concentration, but concentrations in excess of the solubility limit have not been tested. The 72-hour LOEC and the 72-hour EC 50 were clearly higher than the solubility limit. These values could not be quantified due to the absence of toxicity of UREA 4 up to the solubility limit of the test substance in test water. At the microscopic examination of the shape of the algal cells after 72 hours test period no difference was observed between the algae growing in the filtrate and the algal cells in the control. Thus, the shape of the algal cells growing at least up to the solubility limit was obviously not affected. In the control the cell density has increased from nominal N = 1x10E04 cells/mL at the start of the test (0 hours) to N = 69.35 x 10E04 cells/mL (mean value) after 72 hours by a factor of approximately 69. Thus, the algal growth in the control was sufficiently high under the test conditions.

Description of key information

The toxicity to algae was assessed exposing algae under static conditions to a nominal concentration of 100 mg/L. The EC50 was calculated to be > 100 mg/L (nominal, limit concentration). The NOEC was greater or equal 100 mg/L.

Additional information

A limit test was performed according to EU-method C.3 and OECD guideline 201 to demonstrate that the test substance has no toxic effect on algae up to the solubility limit of the test substance in the used test water. At all determinations the number of cells in the filtrate of the supersaturated stock suspension was slightly higher than in the control samples. Therefore, in the filtrate no significant reduction of growth on algal cells was determined compared to the control during the test period of 72 hours. The 72-hour NOEC was determined to be at least up to the solubility limit of the test substance in test water. The NOEC might even be higher than this concentration, but concentrations in excess of the solubility limit have not been tested. The 72-hour LOEC and the 72-hour EC 50 were clearly higher than the solubility limit. These values could not be quantified due to the absence of toxicity of UREA 4 up to the solubility limit of the test substance in test water. At the microscopic examination of the shape of the algal cells after 72 hours test period no difference was observed between the algae growing in the filtrate and the algal cells in the control. Thus, the shape of the algal cells growing at least up to the solubility limit was obviously not affected. In the control the cell density has increased from nominal N = 1x10E04 cells/mL at the start of the test (0 hours) to N = 69.35 x 10E04 cells/mL (mean value) after 72 hours by a factor of approximately 69. Thus, the algal growth in the control was sufficiently high under the test conditions.