Reaction product of Hexamethylene diisocyanate, oligomers with Mercaptopropyltrimethoxysilane

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:

from 2017-06-15 to 2017-06-28

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)

Version / remarks:

2006

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Version / remarks:

01 March 2016

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.5400 (Algal Toxicity, Tiers I and II) (January 2012)

Version / remarks:

1996

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: The test item is poorly water soluble material. In order to achieve the maximum solubility level, the test solution was prepared as follows: a supersaturated solution (100 mg/L nominal loading) was prepared by dispersing/dissolving an amount of 0.08 g test item in 800 mL test medium (OECD medium). This solution was agitated by orbital shaker (~350 rpm) for approx. one day and then the non-dissolved test material was separated by filtration through a membrane filter (0.2 μm) in order to obtain the saturated test solution (corresponding to 100 mg/L nominal concentration).
- Controls: Yes. The dilution water (OECD medium) without addition of the test item was used as a control solution.

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

TEST ORGANISM
- Species: Raphidocelis subcapitata (formerly known as Pseudokirchneriella subcapita and Selenastrum capricornutum) (Printz-Starr).
- Strain number: 61.81 SAG (identical strains: CCAP 278/4; UTEX 1648; ATCC 22662)
- Source: The algae were supplied by the SAG: Collection of Algal Cultures, Inst. Plant Physiology, University of Göttingen, Untere Karspüle 2, D-37073 Göttingen, Germany
- Age of inoculum (at test initiation):
- Method of cultivation: The stock cultures are small algal cultures that are planted on agar regularly. These are transferred to fresh medium at least once every two months under standardised conditions according to the test guidelines. The pre-culture is intended to give an amount of algae suitable for the inoculation of test cultures. The pre-culture was prepared with Algal Mineral Salts Culture Medium, incubated under the conditions of the test and used when still exponentially growing, normally after an incubation period of 2 - 4 days. (The pre-culture was incubated for four days at this test.)

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Test temperature:

22.1 - 22.9 °C (measured in the flask)
21.0 - 23.0 °C (measured within the climate chamber)

pH:

7.70 - 9.20

Nominal and measured concentrations:

Nominal concentration: 100 mg/L
No measured concentrations.

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer flaks of ~250 mL volume with 100 mL test medium.
- Type: closed. The flasks were covered with air-permeable stoppers.
- Initial cells density: 10^4 cells/mL
- No. of vessels per concentration (replicates): 6
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: Continuously illumination
- Light intensity and quality: The average light intensity during the test was 7900 lux, which was ensured with fluorescent lamps (with a spectral range of 400-700 nm). The differences in light intensity between the test vessels did not exceed ± 15 %.

EFFECT PARAMETERS MEASURED:
- Determination of cell concentrations: counting chamber

PRELIMINARY TEST
- Test concentrations: A non-GLP preliminary experiment was carried out at saturation concentration (100 mg/L nominal loading) to determine the approximate toxicity of the test item.
- Results used to determine the conditions for the definitive study: Significant toxic effects were not observed during the preliminary test therefore only one test concentration at saturation (equivalent to 100 mg/L nominal concentration) was tested in a limit test. A concurrent control group ran parallel.

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: growth rate and yield

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: growth rate and yield

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 and yield

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: growth rate and yield

Duration:

72 h

Dose descriptor:

EC20

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: growth rate and yield

Details on results:

- Growth Inhibition: The growth inhibition calculated for the 72 hours exposure in treatment group compared to the control was -1.2 % for the average specific growth rate and -6.7 % for the yield.
The results of the statistical evaluation showed that the 0-72 h average specific growth rate and yield at the treatment group (saturated solution; equivalent to 100 mg/L nominal concentration) was not statistically significantly different from the untreated control (T-test; 2-tailed; α = 0.05).
- Microscopic Examination: Abnormal appearance of the algal cells was not observed during the experiment.

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- 72 h ErC50: 0.99 mg/L, (95 % confidence limits: 0.68 – 1.49 mg/L)
- 72 h EyC50: 0.59 mg/L, (95 % confidence limits: 0.47 – 0.75 mg/L)

Validity Criteria of the Study
= Cell density in the control cultures increased by a factor of more than 16 (by a factor of 146.33) within 72 hours. This corresponds to a specific growth rate of 1.66 day-1.
= The mean coefficient of variation for section-by-section specific growth rates (days 0-1, 1-2 and 2-3, for 72 h-tests) in the control cultures did not exceed 35 %.
- CV for section-by-section growth rate day 0-1: 14.14 %
- CV for section-by-section growth rate day 1-2: 12.55 %
- CV for section-by-section growth rate day 2-3: 3.00 %
The mean coefficient of variation for section-by-section specific growth rates: 9.89 %.
= The coefficient of variation of average specific growth rates during the whole test period in replicate control cultures did not exceed 7 % in test.
- CV for average specific growth rate day 0-3: 2.14 %
All validity criteria were met, therefore the study can be considered as valid.

 

Growth Inhibition
Biological results are based on the nominal test item concentration.
The growth inhibition calculated for the 72 hours exposure in treatment group compared to the control was -1.2 % for the average specific growth rate and -6.7 % for the yield.
The results of the statistical evaluation showed that the 0-72 h average specific growth rate and yield at the treatment group (saturated solution; equivalent to 100 mg/L nominal concentration) was not statistically significantly different from the untreated control (T-test; 2-tailed; α = 0.05).
Accordingly, the 96-h NOEC was determined as the saturation concentration (equivalent to 100 mg/L nominal concentration).
The 96-h EC50 and LOEC were determined to be higher than saturation (equivalent to 100 mg/L nominal concentration).

Microscopic Examinations
Abnormal appearance of the algal cells was not observed during the experiment.

Validity criteria fulfilled:

yes

Conclusions:

In this 72-h algal growth inhibition test with Raphidocelis subcapitata, the obtained results showed that the test item had no toxic effect on the algae at aquatic saturation (equivalent to 100 mg/L nominal concentration). Accordingly, the 72-h EC10, EC20, EC50 and the LOEC values based on growth rate and yield were determined to be >100 mg/L. The 72-h NOEC was determined to be 100 mg/L. The results are based on nominal test item concentrations.

Executive summary:

A 72-h algal growth inhibition test with Raphidocelis subcapitata according to OECD guideline 201 was perfromed. The test item is a poorly water soluble material and therfore a saturated solution (100 mg/L nominal loading) was prepared and the alga (initial cell denisty: 10^4 cells/mL) were exposed to the test media containing the test item plus a control group for 72 hours. In this 72-h algal growth inhibition test with Raphidocelis subcapitata, the obtained results showed that the test item had no toxic effect on the algae at aquatic saturation (equivalent to 100 mg/L nominal concentration). Accordingly, the 72-h EC10, EC20, EC50 and the LOEC values based on growth rate and yield were determined to be >100 mg/L. The 72-h NOEC was determined to be 100 mg/L. The results are based on nominal test item concentrations.

Description of key information

In a 72-h algal growth inhibition test with Raphidocelis subcapitata an EC10, EC20, EC50 and a LOEC values based on growth rate and yield were determined to be >100 mg/L. The 72-h NOEC was determined to be 100 mg/L. The results are based on nominal test item concentrations.

Additional information

A 72-h algal growth inhibition test with Raphidocelis subcapitata according to OECD guideline 201 was perfromed. The test item is a poorly water soluble material and therfore a saturated solution (100 mg/L nominal loading) was prepared and the alga (initial cell denisty: 10^4 cells/mL) were exposed to the test media containing the test item plus a control group for 72 hours. In this 72-h algal growth inhibition test with Raphidocelis subcapitata, the obtained results showed that the test item had no toxic effect on the algae at aquatic saturation (equivalent to 100 mg/L nominal concentration). Accordingly, the 72-h EC10, EC20, EC50 and the LOEC values based on growth rate and yield were determined to be >100 mg/L. The 72-h NOEC was determined to be 100 mg/L. The results are based on nominal test item concentrations.