reaction product of diphenylmethanediisocyanate, toluenediisocyanate ( reaction mass of isomers: 65 % 2,4- and 35 % 2,6-diisocyanate), octylamine, oleylamine and 4-ethoxyaniline (molar ratio 3.88:1:6.38:0.47:2.91)

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:

1999-01-27 to 1999-05-19

Reliability:

1 (reliable without restriction)

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:

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 dosing 50 mg of the test substance into 500 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 10 minutes and intense stirring. The supersaturated stock suspension was stirred on a magnetic stirrer at room temperature in the dark over approximately 96 hours to dissolve respectively disperse a maximum concentration of the test substance in the stock suspension. 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. Due to this procedure it was seen to that the substance was solved in the test water up to the solubility limit. All particles of the substance up to a size of 0.2 µm were solved or suspended in the test water. Thus, it was guaranteed that the substance was tested at the maximum solubility. No concentrations above the solubility limit of the test substance in the used test water were tested to avoid physical effects of the test substance on to algae. Additionally, a control was tested in parallel. Thus, a limit test was performed to demonstrate that the tests substance has no toxic effect on algae up to the solubility limit of the test substance in the used test water.

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 (laboratory, culture collection): The algae were supplied by the "Sammlung von Algenkulturen, Pflanzenphysiologisches Institut der Universität Göttingen", D-37073 Göttingen, Germany.
- Method of cultivation: The algae were 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

Test temperature:

23 °C

pH:

7.4 to 7.5 at test start
9.8 to 9.9 at test end

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/mL
- Control end cells density: 56.53 x 10E04 cells/mL (mean value)
- No. of vessels per concentration (replicates): three replicates
- No. of vessels per control (replicates): six replicates

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- in accordance to the guideline

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: continuous illumination
- Light intensity and quality: 8973 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

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

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 (for algal test): yes
- Observation of abnormalities: no remarkable observations

Validity criteria fulfilled:

yes

Conclusions:

The test item shows no toxic effects up to a nominal concentration of 100 mg/L after 72 hours of exposure.

Executive summary:

The purpose of this test was to determine the inhibitory effect of the test substance on the growth of the freshwater green algal species Scenedesmus subspicatus. Exponentially growing cultures of this green algal species were exposed to the test substance under defined conditions. Due to the low water solubility of the test substance, a filtrate of a supersaturated stock suspension and a control were tested. Thus, a limit test was performed to demonstrate that the test substance has no toxic effect on algae up to the solubility limit in the test water. No concentrations in excess of the solubility limit of the test substance in test water have been tested. A static, non-renewal exposure system was used. The inhibition of growth in relation to control cultures was determined over a test period of 72 hours, and thus over several algal generations. 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 of the test substance in the used test water. These values could not be quantified due to the absence of toxicity of the test substance up to the tested concentration.

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.

Key value for chemical safety assessment

EC50 for freshwater algae:

100 mg/L

EC10 or NOEC for freshwater algae:

100 mg/L

Additional information

The purpose of this test was to determine the inhibitory effect of the test substance on the growth of the freshwater green algal species Scenedesmus subspicatus according to EU-method C.3 and OECD guideline 201. Exponentially growing cultures of this green algal species were exposed to the test substance under defined conditions. Due to the low water solubility of the test substance, a filtrate of a supersaturated stock suspension and a control were tested. Thus, a limit test was performed to demonstrate that the test substance has no toxic effect on algae up to the solubility limit in the test water. No concentrations in excess of the solubility limit of the test substance in test water have been tested. A static, non-renewal exposure system was used. The inhibition of growth in relation to control cultures was determined over a test period of 72 hours, and thus over several algal generations. 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 of the test substance in the used test water. These values could not be quantified due to the absence of toxicity of the test substance up to the tested concentration.