9-Octadecenoic acid (Z)-, sulfonated, potassium salts

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 December 03, 2007 to December 11, 2007

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:

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

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Controls: Negative control (i.e., culture medium)

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: Green alga, Pseudokirchneriella subcapitata
- Source (laboratory, culture collection): Original alga cultures were obtained from the University of Toronto Culture Collection and had been maintained in culture medium at Wildlife International, Ltd., Easton, Maryland.
- Age of inoculum (at test initiation): At least 2 weeks old at test initiation.

ACCLIMATION
- Culturing media and conditions (same as test or not): Algal cells were taken from a culture that had been transferred to fresh media 3 d prior to test initiation.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Post exposure observation period:

Observations were made approximately 24, 48, 72 and 96 h after test initiation.

Test temperature:

ranged from 23.7 to 23.9°C

pH:

ranged from 7.3 to 7.5 (i.e., beginning of the test); ranged from 8.0 to 8.7 (i.e., at test termination)

Nominal and measured concentrations:

Nominal concentration: 0, 3.1, 6.3, 13, 25, 50 and 100 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 mL sterile Erlenmeyer flasks plugged with foam stoppers and contained 100 mL of test or control medium.
- Initial cells density: At test initiation an inoculum of the algal cells was added to each test chamber to achieve a nominal concentration of approximately 10,000 Pseudokirchneriella cells/mL.
- Inoculation: An inoculum of the algal cells was prepared in freshwater algal medium at a concentration of approximately 1.0E6 cells/mL. The concentration of algal cells was veified using a hemacytometer and microscope, and 1.0 mL of the inoculum was added to each test chamber to achieve a nominal concentration of approximately 10,000 cells/mL at test initiation.
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3

GROWTH MEDIUM
- Culture medium: Freshwater algal medium.

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Stock nutrient solutions were prepared by adding reagent-grade chemicals too purified Wildlife International, Ltd. well water.

OTHER TEST CONDITIONS
- Sterile test conditions: Yes (i.e., by filtration, 0.22 µm)
- Adjustment of pH: to 7.5 (i.e., measured with a Thermo Orion Model 525 Aplus pH meter)
- Light intensity and quality: Ranged from 4,030 to 4,650 lux (i.e., measured with a SPER Scientific 840006C light meter)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell densities: Samples were collected from each replicate test chamber at approximately 24 h intervals during the test to determine cell densities, which were subsequently used to calculate areas under the growth curve (biomass) and growth rates.
- Other: Cell densities, area under the growth curve and growth rates were used to calculate percent inhibition values relative to the control over the 96 h exposure period.

TEST CONCENTRATIONS
- Test concentrations: A primary stock solution at a nominal concentration of 100 mg/mL was prepared by dissolving 0.100 g of test substance in 1,000 mL of freshwater algal medium.
- After mixing: All test solutions appeared clear and colorless.

Reference substance (positive control):

no

Key result

Duration:

96 h

Dose descriptor:

EC10

Effect conc.:

62 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 52 - 75 mg/L

Key result

Duration:

96 h

Dose descriptor:

EC10

Effect conc.:

ca. 32.8 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Key result

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

> 53 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Key result

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

50 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

ca. 26.5 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Key result

Duration:

96 h

Dose descriptor:

EC10

Effect conc.:

14 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: 11 - 19 mg/L

Key result

Duration:

96 h

Dose descriptor:

EC10

Effect conc.:

ca. 7.4 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

biomass

Key result

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

ca. 40 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: 35-45 mg/L

Key result

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

ca. 21.2 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

biomass

Key result

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

13 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Key result

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

ca. 6.9 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

biomass

Reported statistics and error estimates:

Cell densities, growth rates and area under the growth curve were analyzed statistically to estimate ECx (i.e. EC10 and EC50) values. The ECx values are defined as the theoretical test concentrations that would produce an x% reduction in cell density (i.e., ECx), growth rate (i.e., ErCx) and area under the growth curve (i.e., EbCx) in comparison to the negative control, and the corresponding 95% confidence limits for each 24 h exposure interval. ECx values were calculated by non-linear regression. The cell density, area under the growth curve and growth rate data were evaluated for normality and homogeneity of variance (i.e., p = 0.01) using the Shapiro-Wilk's and Levene's test, respectively.

After 96 h of exposure, there were no signs of adherence of cells to the test chambers or aggregation/flocculation of algae in the controls or in any treatment group. There were no noticeable changes in cell morphology in any of the tested concentrations when compared to the control.

Validity criteria fulfilled:

yes

Conclusions:

Under the study conditions, 96 h growth rate EC10, EC50 and NOEC values were 62, >100 and 50 mg/L (i.e. ca. 32.8, >53 and 26.5 mg a.i./L), respectively. The 96 h biomass EC10, EC50 and NOEC values were 14, 40 and 13 mg/L (i.e. ca. 7.4, 21.2 and 6.9 mg a.i./L), respectively.

Executive summary:

A study was conducted to determine the acute toxicity of the test substance (purity 53%) to freshwater alga, Pseudokirchneriella subcapitata according to OECD Guideline 201, EU Method C.3 and EPA OPPTS 850.5400, in compliance with GLP. Algae were exposed to test substance at 3.1, 6.3, 13, 25, 50 and 100 mg/L, equivalent to 1.64, 3.34, 6.89, 13.25, 26.5 and 53 mg a.i./L, for 96 h under static conditions. Test substance concentration levels were not determined analytically. A negative control (culture medium) was included and the test was performed in triplicate. At study initiation, an inoculum of the algal cells was added to each test chamber to achieve a nominal concentration of approximately 10,000 Pseudokirchneriella cells/mL. Cell density, biomass and growth rate were analysed approximately 24, 48, 72 and 96 hours after test initiation. Under the study conditions, 96 h growth rate EC10, EC50 and NOEC values were 62, >100 and 50 mg/L (i.e. ca. 32.8, >53 and 26.5 mg a.i./L), respectively. The 96 h biomass EC10, EC50 and NOEC values were 14, 40 and 13 mg/L (i.e. ca. 7.4, 21.2 and 6.9 mg a.i./L), respectively (Minderhout, 2008).

Key value for chemical safety assessment

EC50 for freshwater algae:

48.2 mg/L

EC10 or NOEC for freshwater algae:

9.5 mg/L

Additional information

A study was conducted to determine the acute toxicity of the test substance (purity 53%) to freshwater alga, Pseudokirchneriella subcapitata according to OECD Guideline 201, EU Method C.3 and EPA OPPTS 850.5400, in compliance with GLP. Algae were exposed to test substance at 3.1, 6.3, 13, 25, 50 and 100 mg/L, equivalent to 1.64, 3.34, 6.89, 13.25, 26.5 and 53 mg a.i./L, for 96 h under static conditions. Test substance concentration levels were not determined analytically. A negative control (culture medium) was included and the test was performed in triplicate. At study initiation, an inoculum of the algal cells was added to each test chamber to achieve a nominal concentration of approximately 10,000 Pseudokirchneriella cells/mL. Cell density, biomass and growth rate were analysed approximately 24, 48, 72 and 96 hours after test initiation. Under the study conditions, 96 h growth rate EC10, EC50 and NOEC values were 62, >100 and 50 mg/L (i.e. ca. 32.8, >53 and 26.5 mg a.i./L), respectively. The 96 h biomass EC10, EC50 and NOEC values were 14, 40 and 13 mg/L (i.e. ca. 7.4, 21.2 and 6.9 mg a.i./L), respectively (Minderhout, 2008).