2H-Azepin-2-one, hexahydro-, polymer with 1,6-diisocyanatohexane

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:

2007-05-24 to 2007-07-13

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with acceptable restrictions: high concentration of solvent, no substance specific analytical monitoring

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Version / remarks:

(1992)

Deviations:

no

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

(1984)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Before measurement all biological test solutions were filtered through a membrane filter with a pore size of 0.45 µm to achieve the bioavalable fraction which is represented by the dissolved organic carbon (DOC). Samples were taken at 0 hours and 72 hours and the DOC content was measured.

Vehicle:

no

Details on test solutions:

To produce the only test concentration 124.6 mg of the test item were added to 1 litre of dilution water, treated for 60 seconds at 8000 rpm with an ultra turrax and afterwards stirred for 24 h on a magnetic stirrer. Finally undissolved particles of the test item were removed by filtration using aseptic filters of pore size 0.2 μm.

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

Pre-cultures are set up three days before the start of a test. They are grown under identical exposure conditions as the stock cultures, except from the use of a different nutrient medium. For the test cultures the algal inocula are taken from the exponentially-growing pre-culture and are mixed with the nutrient medium to make up to a final cell density of about 5000 cells per millilitre in the test medium.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Test temperature:

21-25°C +/- 2°C

pH:

Control 8.2 at 0h, 8.2 after 72 h
Test substance replicates 8.4 at 0h, 8.3 after 72 h

Nominal and measured concentrations:

100 mg/L solution nominal = 28 mg solvent/L + 72 mg 2H-Azepin-2-one, hexahydro-, polymer with 1,6-diisocyanatohexane/L
measured DOC: 11.6 mg/L at 0h, 12.58 mg/L after 72 h
For a solution of 28 mg solvent / 100 ml test water a DOC of 15.3 mg/l is expected (54.53 % carbon in molecular formula).

Details on test conditions:

The test was performed as a limit test with a nominal concentration of 100 mg test item/L. Three replicates were used per concentration and 6 replicates for the control. Separate replicates were used for the determination of pH and test substance concentration and treated like all other replicates.

Reference substance (positive control):

no

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

Reported statistics and error estimates:

No statistical evaluation was performed since no adverse effects were observed up to the nominal limit concentration of 100 mg test item/L.

Validity criteria fulfilled:

yes

Conclusions:

The test item showed no toxic effects on algae at a limit test concentration of 100 mg test item/L, corresponding to 72 mg 2H-Azepin-2-one, hexahydro-, polymer with 1,6-diisocyanatohexane/L.

Executive summary:

A study was performed to assess adverse effects of a 72 % solution of 2H-Azepin-2-one, hexahydro-, polymer with 1,6-diisocyanatohexane in 2-methoxy-1-methylethylacetate on the growth (= increase in cell density) and the growth rate (= rate of increase in cell density with time) of the planktonic freshwater algal species Desmodesmus subspicatus over several generations.

The study was conducted in accordance with EEC Methods for Determination of Ecotoxicity Annex to Directive 92/69/EEC (O.J. No. L383A, 29.12.92) Part C, Method 3 'Algal inhibition test' which is in most parts equivalent to the OECD Guideline for Testing of Chemicals No. 201 'Alga, Growth Inhibition Test'.

Exponentially growing algal cells were exposed for a period of 72 hours to a limit test concentration of nominally 100 mg test item/L in water. Auxiliaries used to prepare the test media were an ultra turrax, a magnetic stirrer and aseptic filters.

The cell densities were measured at 24 hour intervals. Inhibition of the algal population was measured as reduction in growth (index b) and growth rate (index r), relative to control cultures grown under identical conditions. The following values were determined:

Results [mg test item/L]:

ErC 50 (0-72 h) : > 100

EbC 50 (0-72 h) : > 100

No toxic effects against algae at a limit test concentration of 100 mg test item/L, corresponding to 72 mg 2H-Azepin-2-one, hexahydro-, polymer with 1,6-diisocyanatohexane/L.

All results are expressed in terms of nominal concentrations. The determination of the DOC indicated that the water soluble solvent was found in the test solution while the insoluble 2H-Azepin-2-one, hexahydro-, polymer with 1,6-diisocyanatohexane was removed before test start.

Description of key information

A study was performed to assess adverse effects of a 72 % solution of 2H-Azepin-2-one, hexahydro-, polymer with 1,6-diisocyanatohexane in 2-methoxy-1-methylethylacetate on the growth (= increase in cell density) and the growth rate (= rate of increase in cell density with time) of the planktonic freshwater algal species Desmodesmus subspicatus over several generations.
The study was conducted in accordance with EEC Methods for Determination of Ecotoxicity Annex to Directive 92/69/EEC (O.J. No. L383A, 29.12.92) Part C, Method 3 'Algal inhibition test' which is in most parts equivalent to the OECD Guideline for Testing of Chemicals No. 201 'Alga, Growth Inhibition Test'.
Exponentially growing algal cells were exposed for a period of 72 hours to a limit test concentration of nominally 100 mg test item/L in water.
The cell densities were measured at 24 hour intervals. Inhibition of the algal population was measured as reduction in growth (index b) and growth rate (index r), relative to control cultures grown under identical conditions. The following values were determined:
Results [mg test item/L]:
ErC 50 (0-72 h) : > 100
EbC 50 (0-72 h) : > 100

Key value for chemical safety assessment

EC50 for freshwater algae:

100 mg/L

Additional information

No toxic effects against algae at a limit test concentration of 100 mg test item/L, corresponding to 72 mg 2H-Azepin-2-one, hexahydro-, polymer with 1,6-diisocyanatohexane/L.

All results are expressed in terms of nominal concentrations. The determination of the DOC indicated that the water-soluble solvent was found in the test solution while the insoluble 2H-Azepin-2-one, hexahydro-, polymer with 1,6-diisocyanatohexane was removed before test start.