Alcohols, C12-15, ethoxylated

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

effects on growth of green algae

Type of information:

experimental study

Adequacy of study:

key study

Study period:

03 May - 11 Jun 2021

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

206, corrected 2011

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: all concentrations
- Sampling method: sampling at 0h (fresh solutions) and aftter 24, 48 and 72 h (aged solutions)
- Sample storage conditions before analysis: The samples were mixed with 10 mL acetonitrile and stored deep-frozen (= - 18 °C) until analysis.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A stock solution with a nominal concentration of 20 mg/L was prepared by adding the necessary amount of test item to a volumetric flask. Test medium was added and the solution was homogenised by stirring on a magnetic stirrer for 1 hour. The solution was observed to be slightly turbid. Test item concentrations were prepared by dilution with test medium. All dilutions were observed to be clear and transparent.

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Strain: SAG 61.81
- Source (laboratory, culture collection): purchased from MBM Sciencebridge GmbH, Göttingen, Germany
- Method of cultivation: The algae are grown semi-continuously in sterile cultures in the laboratory. Old medium is periodically replaced by fresh mineral solution in order to keep the algae in an exponential growth state.

ACCLIMATION
- Acclimation period: 3 to 4 days
- Culturing media and conditions (same as test or not): same

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

22.4 – 23.3 °C

pH:

7.65 -.8.38

Nominal and measured concentrations:

Nominal test item concentrations: 1.00, 0.500, 0.250, 0.125, 0.0625 mg/L
Geometric mean measured test item concentrations: 0.0400, 0.0300, 0.0100, 0.0125, 0.00563 mg/L (based on 2 representative constituents)

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer flasks (glass), nominal volume 100 mL
- Type (delete if not applicable): covered by aluminium caps
- Fill volume: ~50 mL
- Initial cells density: 0.5 × E*4 cells/mL
- Control end cells density: 69.27 × E*4 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes acc. to AAP-Medium (according to Annex 3 of OECD 201)

TEST MEDIUM / WATER PARAMETERS
- Culture medium different from test medium: no
- Intervals of water quality measurement: pH at test start and test end; temperature continously

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod:continous illumination
- Light intensity and quality: 95.0 µEm-2s-1 (mean light intensity)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: cell densities were determined by a fluorimeter at time points. 0, 24, 48 and 72 h

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: 0.0100, 0.100, and 1.00 mg/L
- Results used to determine the conditions for the definitive study: EC50 (72h): >0.10 - < 1.0 mg/L

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.025 mg/L

95% CI:

>= 0.021 - <= 0.024

Nominal / measured:

meas. (geom. mean)

Conc. based on:

other: based on two representative constituents

Remarks:

C13EO2 and C13EO3

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.031 mg/L

95% CI:

>= 0.03 - <= 0.032

Nominal / measured:

meas. (geom. mean)

Conc. based on:

other: based on two representative constituents

Remarks:

C13EO2 and C13EO3

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.013 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

other: based on two representative constituents

Remarks:

C13EO2 and C13EO3

Basis for effect:

growth rate

Details on results:

- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): At nominal test item concentration of 0.500 mg/L slender and bloated cells were observed.

Results with reference substance (positive control):

- ErC50 (72 h): 1.55 mg/L (NOErC(72 h): 0.320 mg/L)
- Other: test performed Jan 2021

Reported statistics and error estimates:

The NOEC and LOEC were determined using a multiple comparison method (multiple Welch's t-test with Bonferroni-Holm adjustment, left sided, for growth rate, Jonckheere-Terpstra test, left sided, for yield). The EC10, 20, 50-values for growth rate were determined by Weibull analysis using maximum likelihood regression, the EC10, 20, 50-values for yield were determined by probit analysis using linear weighted regression.

Table 1: Validity criteria for OECD 201 (2006)

Criterion from the guideline	Outcome	Validity criterion fulfilled
The biomass in the control cultures should have increased exponentially by a factor of at least 16 within the 72-hour test period.	125.95	yes
The mean coefficient of variation for section-by-section specific growth rates (days 0-1, 1-2 and 2-3, for 72-hour tests) in the control cultures must not exceed 35%	10%	yes
The coefficient of variation of average specific growth rates during the whole test period in replicate control cultures must not exceed 7% in tests with Pseudokirchneriella subcapitata and Desmodesmus subspicatus. For other less frequently tested species, the value should not exceed 10%.	1.0%	yes

 

Table 2:   Percentage inhibition of growth rate

Nominal Conc.	% Inhibition of growth rate
[mg/L]	0 h – 24 h	0 h – 48 h	0 h – 72 h
Control	0.0	0.0	0.0
0.0625	-5.3	-0.3	-0.9
0.125	10.3	-1.7	0.0
0.250	32.4	11.8	5.8
0.500	103.6	64.9	40.0*
1.00	310.6	208.9	141.2*

* Statistically significant different to the control (left-sided, p=0.05)

 

Validity criteria fulfilled:

yes

Remarks:

please see table 1 at "Any other information on results incl. tables"

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

02 NOV - 26 NOV 1992

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

yes

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A stock solution was prepared with a nominal concentration of 2000 mg/L. Testconcentrations were prepared by dilution.

Test organisms (species):

Skeletonema costatum

Details on test organisms:

TEST ORGANISM
- Strain: NIVA BAC1
- Age of inoculum (at test initiation): 3 d

Test type:

static

Water media type:

saltwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

20.5 - 21.0 °C

pH:

8.1 - 9.0

Nominal and measured concentrations:

Nominal test concentrations: 0, 0.10, 0.32, 1.00, 3.20 and 10.00 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 100 mL, all-glass,
-Fill volume: 50 mL test medium
- Initial cells density: 4 x 10 exp. 4 algal cells/mL
- Control end cells density: 74.55 x 10 exp. 4 algal cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes, ISO-medium formulated according to the International Standards "Water quality - Marine algal growth inhibition test"

OTHER TEST CONDITIONS
- Photoperiod: continuous illumination
- Light intensity and quality: 6000 - 8000 lux (TLD-lamps of 18 Watt, Philips, Spain)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: counting chamber at 0 h, spectrophotometer at 24, 48 and 72 h

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: 0.1 - 1000 mg/L increasing by a factor 10
- Results used to determine the conditions for the definitive study: NOEC > 10 mg/L

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

1 - 3.2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.32 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.3 mg/L

95% CI:

>= 0.01 - <= 1.07

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 d

Dose descriptor:

NOEC

Effect conc.:

0.1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Details on results:

- Exponential growth in the control (for algal test): yes

Results with reference substance (positive control):

ErC50 (72 h): 3.2 - 5.6 mg/L (nominal)

Validity criteria fulfilled:

not applicable

Description of key information

EC50 (72 h): 0.0311 mg/L

EC10 (72 h): 0.0255 mg/L

Additional information

The key study, investigating the toxicity of Alcohols, C12-15, branched and linear, ethoxylated to aquatic algae, was performed according to guideline OECD 201. In the GLP guideline study, green algae of the species Raphidocelis subcapitata, were exposed to nominal test substance concentrations of 0.0625, 0.125, 0.250, 0.500 and 1,.00 mg/L.. The test concentrations were analytically monitored by HPLC-MS/MS by analysing the concentration of two representative constituents. The time weighted mean concentrations were 0.00563, 0.0125, 0.0100, 0.0300and 0.0400 mg/L. Based on the algal growth an EC50 (72 h) of 0.0311 mg/L was determined. The EC10 (72 h) was 0.0255 mg/L.

A supporting study, conducted according to OECD GD 201, investigated the growth inhibition of the marine organism Skeletonema costatum. The determined EC50 (72 h) range was 1 – 3.2 mg/L (nominal (NOEC (72 h): 0.32 mg/L).