Alcohols, C9-11, branched and linear, 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:

14 Aug - 15 Sep 2020

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:

2006, 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 (nominal 100 mg/L) was prepared by adding the necessary amount of test item to the test medium. The solution was homogenised by shaking. After shaking, the solution was observed to be clear and transparent. The test concentrations were prepared by diluting the stock solution with test medium. The dilutions were observed to be clear and transparent. All stock and test solutions were prepared with AAP-medium containing algae cells with a target density of 0.5 × E*4 cells per mL.

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:

22.5 – 23.2 °C

pH:

7.47 - 8.42

Nominal and measured concentrations:

Nominal test item concentrations of 10.0, 4.00, 1.60, 0.640, 0.256 mg/L
Geometric mean measured test item concentrations: 6.70, 1.08, 0.272, 0.0704, 0.0461 mg/L (based on 3 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: 61.77 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

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
- Spacing factor for test concentrations: 2.5
- Range finding study
- Test concentrations: 0.0500, 0.500, 5.00 and 50.0 mg/L
- Results used to determine the conditions for the definitive study: EC50 (72h): >0.5 - < 5.0 mg/L

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

1.05 mg/L

95% CI:

>= 0.836 - <= 1.25

Nominal / measured:

meas. (geom. mean)

Conc. based on:

other: based on three representative constituents

Remarks:

C10EO2, C10EO3, C10EO6

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

2.99 mg/L

95% CI:

>= 2.59 - <= 3.39

Nominal / measured:

meas. (geom. mean)

Conc. based on:

other: based on three representative constituents

Remarks:

C10EO2, C10EO3, C10EO6

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.272 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

other: based on three representative constituents

Remarks:

C10EO2, C10EO3, C10EO6

Basis for effect:

growth rate

Results with reference substance (positive control):

- ErC50 (72 h): 1.50 mg/L (NOErC(72 h): 0.320 mg/L)
- Other: test performed Jan 2020

Reported statistics and error estimates:

The NOEC and LOEC were determined by using a multiple comparison method (Dunnetts-t-test, left sided, for yield, Multiple Welch’s test with Bonferroni-Holm adjustment, left sided, for growth rate). The EC10, 20, 50-values were determined with non-linear regression using a 3 parametric logistic cumulative distribution function for growth rate and yield.

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.	123.54	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%	4%	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%.	3%	yes

 

Table 2:         Percentage inhibition of growth rate

NominalConc.	% 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
0.256	-6.3	-7.4	-6.0
0.640	-4.6	-7.5	-4.9
1.60	0.6	-5.1	-4.7
4.00	25.5	20.4	8.0 *
10.0	76.5	99.8	83.9 *

* 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:

10 Sep - 14 Sep 1984

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

no guideline followed

Principles of method if other than guideline:

The acute toxicity to the planktonic alga Selenastrum capricornutum was determined in a 4 days growth test.

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): acetone
- Concentration of vehicle in test medium (final test solution): 0.1 ml/L

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: Green algae
- Strain: ATCC 22662
- Source (laboratory, culture collection): Axenic laboratory culture from the American Type Culture Collection, Maryland, USA
- Method of cultivation: Axenic stock cultures were maintained on agar plates and used to inoculate liquid cultures. From liquid cultures in exponential growth test solutions were inoculated.

CULTURE MAINTENANCE
- On plates: Medium solidified with 1.5% Agar in petri dishes was used. 18h light/6 h dark cycle at 18 - 22 °C, monthly renewal.
- Liquid cultures: Sterile transfer from plates with platinum loop to 50 mL of medium in 250 mL Erlenmeyer flasks. The cultures are maintained at 22 - 26 °C on an orbital incubator under constant light (approx. 3000 lux) for up to 3 days.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Hardness:

No data.

Test temperature:

22 - 26 °C

pH:

7.3 - 8.5

Dissolved oxygen:

No data.

Nominal and measured concentrations:

Nominal: 0.010, 0.022, 0.046, 0.10, 0.22. 0.46, 1.00, 2.20, 4.60, 10.00 mg/L

Details on test conditions:

TEST SYSTEM
- Initial cells density: 500 cells/mL
- Control end cells density: no data
- No. of vessels per concentration (replicates): 3
- No. of vessels per vehicle control (replicates): 6

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of test medium: Nutrient medium according to Miller and Green (1978, EPA-600/9-78-018) with 2 exceptions: 105 µg/L boric acid, 50 mg/L sodium bicarbonate
- Culture medium different from test medium: no
- Intervals of water quality measurement: Monitoring of temperature in one test vessel every 4 h, pH and dissolved oxygen was measured in one control and the highest test concentration at test start, after 2 days and at test end.

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Photoperiod: constant light
- Light intensity and quality: approx. 3000 lux
- Shaker: Cooled, orbital incubator with 100 cycles/min

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: Cells were counted using a Coulter Counter

TEST CONCENTRATIONS
- Spacing factor for test concentrations: approx. 2

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

1.4 mg/L

95% CI:

>= 0.93 - <= 2

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

cell number

Table: Growth of S. capricornutum

Concentration of test substance (mg/L)	Cell concentration x 1000 cells/mL)		Cell number on day 4 as % of mean control cell number on day 4
	Day 2	Day 4
Control	28		-
Control	28		-
Control	26		-
Control	26		-
Control	23		-
Control	23		-
0.010	19		67
0.022	22		85
0.046	22		98
0.100	16		63
0.220	25		99
0.460	28		91
1.000	20		84
2.200	9.4		19
4.600	5.6		1
10.000	4.9		0

Description of key information

EC50 (72 h): 2.99 mg/L (geom. mean)

EC10 (72 h): 1.05 mg/L (geom. mean)

Additional information

The key study investigating the toxicity of Alcohols, C9-11, branched and linear, ethoxylated to aquatic algae was conducted according to OECD 201. In the GLP guideline study the growth inhibition of green algae (Raphidocelis subcapitata) at nominal test item concentrations of 0.256, 0.640, 1.60, 4.00 and 10.0 mg/L was monitored. The test concentrations were analytically monitored by HPLC-MS/MS. The time weighted mean measured concentrations, based on three representative constituents of the UVCB substance, were 0.0461, 0.0704, 0.272, 1.08 and 6.70 mg/L. Based on the algal growth rate an EC50 (72 h) of 2.99 mg/L (geom. mean) was observed. The determined EC10 (72 h) was 1.05 mg/L (geom. mean).

In a supporting study, on the green algae Raphidocelis subcapitata, an EC50 (96 h) of 1.4 mg/L (nominal) based on the cell number was observed.