2-morpholinoethanesulphonic acid

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:

2017-01-31 to 2017-09-21

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:

adopted 23rd March 2006, Annex 5 corrected: 28th July 2011

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Version / remarks:

March 01, 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:

yes

Details on sampling:

- Concentrations: 108 mg/L
- Sampling method: - For determination of the test item concentration, six replicate samples were taken from the test item treatment group and one from the control at the start and at the end of the experiment. The analysis was performed using LC/MS/MS.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: The test solution used in the test was prepared by mechanical dispersion. An amount of 0.0869 g test item was dissolved in 800 mL dilution water (OECD medium) in order to obtain the concentration of 108 mg/L. The test solution was freshly prepared in the testing laboratory just before introduction of algae (start of the experiment).

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: Pseudokirchneriella subcapitata
- Strain: 61.81 SAG
- Source: SAG: Collection of Algal Cultures, 37073 Göttingen, Germany
- Method of cultivation: algae were kept as stock culture on solid agar

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Hardness:

not specified

Test temperature:

22.6 – 23.1 °C (in test flask) and 21.9 – 23.9 °C (in climate chamber)

pH:

7.32– 8.17 (in the control group) and 6.63-7.99 (in the treatment groups)

Dissolved oxygen:

not specified

Salinity:

not applicable

Conductivity:

not specified

Nominal and measured concentrations:

Nominal conc.: 108 mg/L
Measured conc.: The measured concentrations showed very good correlation with the nominal concentrations. The recovery rate after 72 hours was 97 %.

Details on test conditions:

TEST SYSTEM
- Test vessel: glass flasks 250 mL
- Type: air-permeable stoppers
- Material, size, fill volume: - glass, 250 mL, 100 mL
- Initial cells density: 10000 cells/mL
- Control end cells density: approx. 1000000 cells/mL
- No. of vessels per concentration (replicates): 6
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: reconstituted algal growth medium (acc. to OECD TG 201)

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: continuous illumination
- Light intensity and quality: 7673 Lux

EFFECT PARAMETERS MEASURED:
- Determination of cell concentrations: manual counting at 24, 48 and 72-h using a microscopic method with a counting chamber

TEST CONCENTRATIONS
- Range finding study: Yes
- Test concentrations: 108 mg/L
- Results used to determine the conditions for the definitive study: Yes

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

> 108 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: yield (migrated information)

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

> 108 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.:

> 108 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 108 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 108 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: area under the growth curve

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

108 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

108 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

108 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: area under the growth curve

Details on results:

- Exponential growth in the control (for algal test): yes
- Effect concentrations exceeding solubility of substance in test medium: no

Results with reference substance (positive control):

- Results with reference substance valid? YES
- EC50: The 72h ErC50: 0.71 mg/L (95 % confidence limits: 0.66 – 0.77 mg/L)
The 72h EyC50: 0.46 mg/L (95 % confidence limits: 0.42 – 0.49 mg/L)

Validity of the Test

- The cell density in the control cultures increased by a factor of 103.67 within 72 hours. This corresponds to a specific growth rate of 1.55 /day.

- The mean coefficient of variation (CV) 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: 26.44 %

- CV for section-by-section growth rate day 1-2: 19.17%

- CV for section-by-section growth rate day 2-3: 6.36 %

The mean coefficient of variation for section-by-section specific growth rates: 17.32 %.

The coefficient of variation of average specific growth rates during the whole test period (day 0-3) in the control cultures was 1.02 %.

All validity criteria were met. Therefore, the study was considered as valid. 

 

Analytical Results

The mean measured concentration of the test item was 105 % of the nominal at the start and 97 % at the end of the test. The measured test item concentration remained within ± 20 % of the nominal during the test period of 72 hours. Therefore the biological results were based on the nominal concentration.

 

Biological Results

No inhibition was observed in the treated group after 72 hours of exposure compared to the control which was considered to be within the normal biological range.

Table 1: Summary of the Biological Endpoints

Parameter (0-72 h)	Growth rate (ji) [mg/L]	Yield (y) [mg/L]
EC50 95 % conf. limits	> 108 not calculated	> 108 not calculated
NOEC	108	108
LOEC	> 108	> 108

Validity criteria fulfilled:

yes

Conclusions:

Under the test conditions no effects on algae were observed. The No Observed Effect Concentration (NOEC) was determined to be 108 mg/L and the 72-h EC50 values based on growth rate and yield were > 108 mg/L.

Executive summary:

The effect of the test item on algal growth was assessed using the unicellular green alga Raphidocelis subcapitata (formerly known as Pseudokirchneriella subcapitata and Selenastrum capricornutum) in a study according to OECD TG 201 under GLP. For this purpose, alga was exposed to the test item for 72 hours. Based on the results of a non-GLP preliminary test, in which the test item had no toxic effect on algae up to 100 mg/L (limit concentration). Therefore the main test was performed at 108 mg/L including a concurrent control and the reference substance potassium dichromate which served as the reference control. This concentration was chosen for regulatory purposes to achieve the limit test concentration of 100 mg/L for the test item even after a possible correction for the water content. As measured test item concentration remained within ± 20 % of the nominal over the test period of 72 hours, therefore the biological results were based on the nominal concentration. Exponentially-growing cultures of Raphidocelis subcapitata were exposed to the test item over several generations under defined conditions (static test). The algal growth was determined over a fixed test period of 72 hours in relation to a concurrent untreated control culture. Per test concentration and control, six replicates were used. The alga cell concentration was approximately 10e4 cells/mL at the start of the test for all test cultures. Glass flasks with a total capacity of 250 mL were used as test vessels. The volume of the test liquid in the vessels was 100 mL. The alga cell concentration was determined by microscope in each testing flask at 24, 48 and 72 hours. All validity criteria were fulfilled. The No Observed Effect Concentration (NOEC) was determined to be 108 mg/L and the Lowest Observed Effect Concentration (LOEC) was determined to be >108 (limit concentration). Consequently, the 72-h EC₅₀ values based on growth rate and yield were also > 108 mg/L. As a limit test was performed and as no effects were observed, no further statistical analysis was performed.

Description of key information

Under the test conditions no effects on algae were observed. The No Observed Effect Concentration (NOEC) was determined to be 108 mg/L and the 72-h EC₅₀ values based on growth rate and yield were > 108 mg/L (reference 6.1.5-1).

Key value for chemical safety assessment

EC50 for freshwater algae:

108 mg/L

EC10 or NOEC for freshwater algae:

108 mg/L

Additional information

The effect of the test item on algal growth was assessed using the unicellular green alga Raphidocelis subcapitata (formerly known as Pseudokirchneriella subcapitata and Selenastrum capricornutum) in a study according to OECD TG 201 under GLP. For this purpose, alga was exposed to the test item for 72 hours. Based on the results of a non-GLP preliminary test, in which the test item had no toxic effect on algae up to 100 mg/L (limit concentration). Therefore the main test was performed at 108 mg/L including a concurrent control and the reference substance potassium dichromate which served as the reference control. This concentration was chosen for regulatory purposes to achieve the limit test concentration of 100 mg/L for the test item even after a possible correction for the water content. As measured test item concentration remained within ± 20 % of the nominal over the test period of 72 hours, therefore the biological results were based on the nominal concentration. Exponentially-growing cultures of Raphidocelis subcapitata were exposed to the test item over several generations under defined conditions (static test). The algal growth was determined over a fixed test period of 72 hours in relation to a concurrent untreated control culture. Per test concentration and control, six replicates were used. The alga cell concentration was approximately 10e4 cells/mL at the start of the test for all test cultures. Glass flasks with a total capacity of 250 mL were used as test vessels. The volume of the test liquid in the vessels was 100 mL. The alga cell concentration was determined by microscope in each testing flask at 24, 48 and 72 hours. All validity criteria were fulfilled. The No Observed Effect Concentration (NOEC) was determined to be 108 mg/L and the Lowest Observed Effect Concentration (LOEC) was determined to be >108 (limit concentration). Consequently, the 72-h EC₅₀ values based on growth rate and yield were also > 108 mg/L. As a limit test was performed and as no effects were observed, no further statistical analysis was performed.