Magnesium octadecylbenzenesulphonate

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

21 July 2014-24 July 2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Guidance document on aquatic toxicity testing of difficult substances and mixtures, OECD series on testing and assessment number 23, December 14, 2000

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

Samples for analysis were taken from all test concentrations and the control according to the schedule below. In addition, the filter used to prepare the limit concentration was retained for possible analysis of the residue.

Frequency: at t=0 h, t=24 h and t=72 h
Volume : 2.0 ml
Storage : Not applicable, samples were analysed on the day of sampling.

At the end of the exposure period, the replicates with algae were pooled at each concentration before sampling.

Compliance with the Quality criteria regarding maintenance of actual concentrations was demonstrated by running a test vessel at the highest substance concentration but without algae and samples for analysis were taken at the start, after 24 hours of exposure and at the end of the test period.

Vehicle:

no

Details on test solutions:

The batch of EXP1313100 tested was a brown solid that was not completely soluble in test medium at the loading rates initially prepared.

All test solutions were prepared separately. Various loading rates of the test substance were added to the test medium applying two days of magnetic stirring in order to reach maximum solubility. The resulting aqueous mixtures were filtered through a 0.45 µm membrane filter (Whatman) where after the Water Accommodated Fractions (WAFs) were used for testing. WAFs prepared at loading rates of 1.0 and 10 mg/L were observed to be clear and colourless, while the WAF prepared at a loading rate of 100 mg/L was observed to be hazy.

Test organisms (species):

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

Details on test organisms:

Species: Pseudokirchneriella subcapitata, strain: NIVA CHL 1
Source: In-house laboratory culture
Stock culture: Algae stock cultures were started by inoculating growth medium with algal cells from a pure culture on agar. The suspensions were continuously aerated and exposed to light in a climate room at a temperature of 21-24°C.
Light intensity: 60 to 120 µE/m2/s when measured in the photosynthetically effective wavelength range of 400 to 700 nm
Stock culture medium: M1; according to the NPR 6505 (“Nederlandse Praktijk Richtlijn no. 6505”) formulated using Milli-RO water (tap-water purified by reverse osmosis; Millipore Corp., Bedford, Mass., USA)
Pre-culture: 3 days before the start of the test, cells from the algal stock culture were inoculated in culture medium at a cell density of 10000 cells/mL. The pre-culture was maintained under the same conditions as used in the test. The cell density was measured immediately before use.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Hardness:

0.24 mmol(24 mg CaCO3/L)

Test temperature:

between 21 and 23°C

pH:

between 7.9 and 8.2

Nominal and measured concentrations:

Nominal concentrations: WAFs prepared at loading rates of 1.0, 10 and 100 mg/L
Measured concentrations: The initial concentrations in the WAFs prepared at loading rates of 1.0, 10 and 100 mg/L were 0.37, 2.6 and 7.1 mg/L. The two highest loading rate remained stable during the test period (96-109% of initial at the end of the test), while the lowest loading rate decreased to 52% of initial at the end of the test. The concentration obtained in the WAF prepared at a loading rate of 100 mg/L was clearly above the maximum solubility in test medium based on the observed haziness of the test solution. The average exposure concentrations were calculated to be 0.27, 2.6 and 7.7 mg/L.

Details on test conditions:

Test vessels: 100 mL, all-glass, containing 50 mL of test solution
Medium: M2; according to the OECD 201 Guideline, formulated using Milli-RO water
Cell density: An initial cell density of 10000 cells/mL.
Incubation: Capped vessels were distributed at random in the incubator and as such were daily repositioned. During incubation the algal cells were kept in suspension by continuous shaking

Replicates: 6 replicates for both the control and the WAF prepared at 100 mg/L;
3 replicates for the remaining WAFs;
1 extra replicate for the control and all WAFs for sampling purposes;
1 or 2 replicates for each WAF without algae

GROWTH MEDIUM
- Standard medium used: yes
OTHER TEST CONDITIONS
- Sterile test conditions: no
- Adjustment of pH: no
- Photoperiod: continuous
- Illumination: Continuously using TLD-lamps with a light intensity of 90 uE.m-2.s-1.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
72 h NOErC, 72 h NOEyC, 72 h ErC50, 72 h EyC50, 72 h ErC10, 72 h EyC10

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 10
- Test concentrations: control andWAF's prepared at loading rates of 0.1, 1.0, 10 and 100 mg/L

Reference substance (positive control):

yes

Remarks:

potassium dichromate (K2Cr2O7,)

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

7.7 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

7.7 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

other: yield

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

> 7.7 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

> 7.7 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

other: yield

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 7.7 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 7.7 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

other: yield

Duration:

72 h

Dose descriptor:

NOELR

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOELR

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: yield

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: yield

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Yield

Details on results:

Exponential growth in the control (for algal test): yes
No significant differences were recorded between the values for growth rate or yield at any of the test concentrations when compared to the control group.
Microscopic observations at the end of the test revealed a normal and healthy appearance of the exposed cells when compared to the control.

Results with reference substance (positive control):

The EC50 for growth rate inhibition (72h-ERC50) was 1.6 mg/L with a 95% confidence interval ranging from 1.5 to 1.7 mg/L.

The EC50 for yield inhibition (72h-EYC50) was 0.57 mg/L with a 95% confidence interval ranging from 0.51 to 0.62 mg/L.

Reported statistics and error estimates:

For determination of the NOEC and the EC50 the approaches recommended in the OECD guideline 201 were used. An effect was considered to be significant if statistical analysis of the data obtained for the test concentrations compared with those obtained in the negative control revealed significant inhibition of growth rate or inhibition of yield (Williams Multiple Sequential t-test Procedure, a=0.05, one-sided, smaller).

The calculations were performed with ToxRat Professional v. 2.10.05 (ToxRat Solutions® GmbH, Germany).

No EC-values could be calculated because the test substance proved to be non-toxic (EC50 > maximum concentration tested).

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of the present study with Pseudokirchneriella subcapitata, no inhibition of growth rate or inhibition of yield was recorded at any of the concentrations of EXP1313100 tested.

The 72h-EL*50 for both growth rate and yield inhibition was above a loading rate of 100 mg EXP1313100 per litre and correspondingly the No Observed Effect Loading rate was 100 mg/L. The concentration of EXP1313100 in the WAF prepared at a loading rate of 100 mg/L was determined to be 7.7 mg/L based on the average exposure concentration. This concentration was considered to be above the maximum solubility level of EXP1313100 in test medium.

*EL = effective loading rate

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

21 July 2014-24 July 2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Guidance document on aquatic toxicity testing of difficult substances and mixtures, OECD series on testing and assessment number 23, December 14, 2000

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

Samples for analysis were taken from all test concentrations and the control according to the schedule below. In addition, the filter used to prepare the limit concentration was retained for possible analysis of the residue.

Frequency: at t=0 h, t=24 h and t=72 h
Volume : 2.0 ml
Storage : Not applicable, samples were analysed on the day of sampling.

At the end of the exposure period, the replicates with algae were pooled at each concentration before sampling.

Compliance with the Quality criteria regarding maintenance of actual concentrations was demonstrated by running a test vessel at the highest substance concentration but without algae and samples for analysis were taken at the start, after 24 hours of exposure and at the end of the test period.

Vehicle:

no

Details on test solutions:

The batch of EXP1313100 tested was a brown solid that was not completely soluble in test medium at the loading rates initially prepared.

All test solutions were prepared separately. Various loading rates of the test substance were added to the test medium applying two days of magnetic stirring in order to reach maximum solubility. The resulting aqueous mixtures were filtered through a 0.45 µm membrane filter (Whatman) where after the Water Accommodated Fractions (WAFs) were used for testing. WAFs prepared at loading rates of 1.0 and 10 mg/L were observed to be clear and colourless, while the WAF prepared at a loading rate of 100 mg/L was observed to be hazy.

Test organisms (species):

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

Details on test organisms:

Species: Pseudokirchneriella subcapitata, strain: NIVA CHL 1
Source: In-house laboratory culture
Stock culture: Algae stock cultures were started by inoculating growth medium with algal cells from a pure culture on agar. The suspensions were continuously aerated and exposed to light in a climate room at a temperature of 21-24°C.
Light intensity: 60 to 120 µE/m2/s when measured in the photosynthetically effective wavelength range of 400 to 700 nm
Stock culture medium: M1; according to the NPR 6505 (“Nederlandse Praktijk Richtlijn no. 6505”) formulated using Milli-RO water (tap-water purified by reverse osmosis; Millipore Corp., Bedford, Mass., USA)
Pre-culture: 3 days before the start of the test, cells from the algal stock culture were inoculated in culture medium at a cell density of 10000 cells/mL. The pre-culture was maintained under the same conditions as used in the test. The cell density was measured immediately before use.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Hardness:

0.24 mmol(24 mg CaCO3/L)

Test temperature:

between 21 and 23°C

pH:

between 7.9 and 8.2

Nominal and measured concentrations:

Nominal concentrations: WAFs prepared at loading rates of 1.0, 10 and 100 mg/L
Measured concentrations: The initial concentrations in the WAFs prepared at loading rates of 1.0, 10 and 100 mg/L were 0.37, 2.6 and 7.1 mg/L. The two highest loading rate remained stable during the test period (96-109% of initial at the end of the test), while the lowest loading rate decreased to 52% of initial at the end of the test. The concentration obtained in the WAF prepared at a loading rate of 100 mg/L was clearly above the maximum solubility in test medium based on the observed haziness of the test solution. The average exposure concentrations were calculated to be 0.27, 2.6 and 7.7 mg/L.

Details on test conditions:

Test vessels: 100 mL, all-glass, containing 50 mL of test solution
Medium: M2; according to the OECD 201 Guideline, formulated using Milli-RO water
Cell density: An initial cell density of 10000 cells/mL.
Incubation: Capped vessels were distributed at random in the incubator and as such were daily repositioned. During incubation the algal cells were kept in suspension by continuous shaking

Replicates: 6 replicates for both the control and the WAF prepared at 100 mg/L;
3 replicates for the remaining WAFs;
1 extra replicate for the control and all WAFs for sampling purposes;
1 or 2 replicates for each WAF without algae

GROWTH MEDIUM
- Standard medium used: yes
OTHER TEST CONDITIONS
- Sterile test conditions: no
- Adjustment of pH: no
- Photoperiod: continuous
- Illumination: Continuously using TLD-lamps with a light intensity of 90 uE.m-2.s-1.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
72 h NOErC, 72 h NOEyC, 72 h ErC50, 72 h EyC50, 72 h ErC10, 72 h EyC10

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 10
- Test concentrations: control andWAF's prepared at loading rates of 0.1, 1.0, 10 and 100 mg/L

Reference substance (positive control):

yes

Remarks:

potassium dichromate (K2Cr2O7,)

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

7.7 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

7.7 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

other: yield

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

> 7.7 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

> 7.7 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

other: yield

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 7.7 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 7.7 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

other: yield

Duration:

72 h

Dose descriptor:

NOELR

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOELR

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: yield

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: yield

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Yield

Details on results:

Exponential growth in the control (for algal test): yes
No significant differences were recorded between the values for growth rate or yield at any of the test concentrations when compared to the control group.
Microscopic observations at the end of the test revealed a normal and healthy appearance of the exposed cells when compared to the control.

Results with reference substance (positive control):

The EC50 for growth rate inhibition (72h-ERC50) was 1.6 mg/L with a 95% confidence interval ranging from 1.5 to 1.7 mg/L.

The EC50 for yield inhibition (72h-EYC50) was 0.57 mg/L with a 95% confidence interval ranging from 0.51 to 0.62 mg/L.

Reported statistics and error estimates:

For determination of the NOEC and the EC50 the approaches recommended in the OECD guideline 201 were used. An effect was considered to be significant if statistical analysis of the data obtained for the test concentrations compared with those obtained in the negative control revealed significant inhibition of growth rate or inhibition of yield (Williams Multiple Sequential t-test Procedure, a=0.05, one-sided, smaller).

The calculations were performed with ToxRat Professional v. 2.10.05 (ToxRat Solutions® GmbH, Germany).

No EC-values could be calculated because the test substance proved to be non-toxic (EC50 > maximum concentration tested).

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of the present study with Pseudokirchneriella subcapitata, no inhibition of growth rate or inhibition of yield was recorded at any of the concentrations of EXP1313100 tested.

The 72h-EL*50 for both growth rate and yield inhibition was above a loading rate of 100 mg EXP1313100 per litre and correspondingly the No Observed Effect Loading rate was 100 mg/L. The concentration of EXP1313100 in the WAF prepared at a loading rate of 100 mg/L was determined to be 7.7 mg/L based on the average exposure concentration. This concentration was considered to be above the maximum solubility level of EXP1313100 in test medium.

*EL = effective loading rate

Description of key information

Under the conditions of the present study with Pseudokirchneriella subcapitata, no inhibition of growth rate or inhibition of yield was recorded at any concentration tested. The 72h-EL50 for both growth rate and yield inhibition was above a loading rate of 100 mg/L and correspondingly the No Observed Effect Loading rate was 100 mg/L.