Reaction mass of sodium (methylbutyl and pentyl) sulfonate and sodium 1,2-bis(pentyloxycarbonyl)ethanesulphonate

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

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:

2011

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: all test solutions at test start (0 h) and at test end (72 hours) were analysed.
- Sampling method: Samples of the test solution were taken from the bulk solution at the test start and spent test solutions were sampled as composite specimens per treatment group. Specimens were stabilised with methanol (v:v, 1:1)
- Sample storage conditions before analysis: stored deep frozen (≤ -18°C) until they were analysed.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A stock solution was prepared by adding the test item to test medium.
The stock solution was stirred for 5 minutes on a magnetic stirrer.
Stock solution and test vessels were prepared in the following way:
- a stock solution (stock A) was prepared by weighing 2000.0 mg test item into a graduated flask and bringing to a volume of 2000 mL (= 1000.0 mg/L test item)
- 0.38 mL algal inoculum (measured 130 x 104 cells/mL in the stock culture) were added to a 100 mL test volume to result in an initial biomass of 5 x 103 cells/mL


- Controls: blank control

- Test concentration separation factor: 1.5

- Evidence of undissolved material (e.g. precipitate, surface film, etc.): no

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: Desmodesmus subspicatus HILSE
- Strain: strain: 86.81 SAG
- Source (laboratory, culture collection): purchased from MBM ScienceBridge GmbH, Hans-Adolf-Krebs-Weg 1, 37077 Göttingen, Germany

- Age of inoculum (at test initiation): axenic stock cultures grew in culturing vessels for 4 days prior to test initiation;

- Method of cultivation: cultivation was performed in glass flasks with the medium described above; algae were kept at the same temperature and light conditions as in the test itself

ACCLIMATION
- Acclimation period: 4 days
- Culturing media and conditions (same as test or not): yes

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

22.7 – 23.3 °C (recorded continuously in a vessel containing test medium)

pH:

7.22 to 8.20

Nominal and measured concentrations:

Nominal
control (0), 197.5, 296.3, 444.4, 666.7, 1000.0 mg/L test item,
control (0), 196.7, 295.0, 442.5, 663.8, 995.7 mg/L active substance.
Recoveries for fresh samples were in the range from 107 to 109% of nominal, recoveries for spent samples were in the range from 109 to 111%. No test item was found in the control samples.

Details on test conditions:

TEST SYSTEM
- Test vessel:
250 mL Erlenmeyer flask
- Type: air-permeable stoppers
- Material, size, headspace, fill volume:
100 mL test volume
- Aeration:
no
- Initial cells density:
5000 cells/mL
- Control end cells density:
305000 cells/mL
- No. of vessels per concentration (replicates):
3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes
- Detailed composition if non-standard medium was used:
AAP medium

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water:
AAP medium according to OECD 201
- Culture medium different from test medium: no


OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH:
no
- Photoperiod:
continuous
- Light intensity and quality:
cold white fluorescent light; light intensity was measured once before test start: light intensity: on average 72 µE·m-2·s-1 measured at 400-700 nm differences from the selected light intensity over the test area did not exceed the range ± 15%


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: 24, 48 and 72 hours after test start, the biomass (number of cells per millilitre) in all test vessels including control was determined by direct counting (actual microscopic cell count using a Neubauer counting chamber).
- Chlorophyll measurement:
no

TEST CONCENTRATIONS
- Spacing factor for test concentrations:
1.5
- Justification for using less concentrations than requested by guideline:
NA

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

> 995.7 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 995.7 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Details on results:

- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): No differences such as sedimentation of test solution, cell aggregation or colour differences of algae cells were noticed between the control vessels and the test vessels containing the test item during the test.
- Unusual cell shape: none
- Colour differences: none
- Flocculation: none
- Adherence to test vessels: none
- Aggregation of algal cells: none
- Other:
- Any stimulation of growth found in any treatment: yes, but < 1% of the control growth rate.
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: no
- Effect concentrations exceeding solubility of substance in test medium: no

Results with reference substance (positive control):

- Results with reference substance valid? yes
- EC50: 1.11 mg/L

Reported statistics and error estimates:

A non-regression analysis was performed using individual replicate responses, not treatment group means.
From average specific growth rates and yield, recorded in a series of test solutions, effect concentrations of ErC10, ErC20 and ErC50, (average specific growth rate) and EyC10, EyC20 and EyC50 (yield) was determined using concentrations-response modelling (linear regression analysis).

Validity criteria fulfilled:

yes

Conclusions:

72h-ErC10 > 995.7 mg a.i./L
72h-ErC50 > 995.7 mg a.i./L

Executive summary:

The growth inhibition of Reaction mass of sodium (methylbutyl and pentyl) sulfonate and sodium 1,2-bis(pentyloxycarbonyl)ethanesulphonate  [EC 941-224-7] to Desmodesmus subspicatus was determined in a 72 h static GLP algae growth inhibition test. The test design was based on the OECD 202 guideline. The nominal test concentrations were 0 (control), 197.5, 296.3, 444.4, 666.7, 1000.0 mg/L test item, corresponding to 0 (control), 196.7, 295.0, 442.5, 663.8, 995.7 mg/L active substance. Six control replicates and 3 replicates from each test solution were set up. Dose verification analysis was performed at 0 and 72 hours. Recoveries for fresh samples were in the range from 107 to 109% of nominal, recoveries for spent samples were in the range from 109 to 111%. Consequently, the test concentration was stable and the reported biological results are related to the nominal test item concentration. No test item was found in the control samples. 24, 48 and 72 hours after test start, the biomass (number of cells per millilitre) in all test vessels including control was determined by direct counting (actual microscopic cell count using a Neubauer counting chamber). All validity criteria for this type of study were met. The 72 -hour ErC10 and ErC50 are > 995.7 mg active substance/L based on the nominal concentration.

This study is considered to be relevant and acceptable for the risk assessment of the registered substance.

Description of key information

ErC10 freshwater algae: > 995.7 mg active substance/L
ErC50 freshwater algae: > 995.7 mg active substance/L

 

Key value for chemical safety assessment

EC50 for freshwater algae:

995.7 mg/L

EC10 or NOEC for freshwater algae:

995.7 mg/L

Additional information

The growth inhibition of Reaction mass of sodium (methylbutyl and pentyl) sulfonate and sodium 1,2-bis(pentyloxycarbonyl)ethanesulphonate  [EC 941-224-7] to Desmodesmus subspicatus was determined in a 72 h static GLP algae growth inhibition test. The test design was based on the OECD 202 guideline. The nominal test concentrations were 0 (control), 197.5, 296.3, 444.4, 666.7, 1000.0 mg/L test item, corresponding to 0 (control), 196.7, 295.0, 442.5, 663.8, 995.7 mg/L active substance. Six control replicates and 3 replicates from each test solution were set up. Dose verification analysis was performed at 0 and 72 hours. Recoveries for fresh samples were in the range from 107 to 109% of nominal, recoveries for spent samples were in the range from 109 to 111%. Consequently, the test concentration was stable and the reported biological results are related to the nominal test item concentration. No test item was found in the control samples. 24, 48 and 72 hours after test start, the biomass (number of cells per millilitre) in all test vessels including control was determined by direct counting (actual microscopic cell count using a Neubauer counting chamber). All validity criteria for this type of study were met. The 72 -hour ErC10 and ErC50 are > 995.7 mg active substance/L based on the nominal concentration.

This study is considered to be relevant and acceptable for the risk assessment of the registered substance.