Guerbet alcohols, C24-26, branched and cyclic

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:

June to September, 2020

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:

March 13, 2006

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: a test item solution at a loading rate of 10 mg/l was prepared with OECD algae growth medium. 0.1003 g of the test item was weighed and 1000 ml growth medium was added to dissolve the test item. The solution was mixed by magnetic stirreing at a speed of 240 rpm for 48 hours. After stirring, the saturated solution was allowed to stand in a separation funnel for 60 minutes and the lower solution was run-off as the test solution. The test solutions were dispensed into 6 replicate flasks respectively and each replicate contained 100 ml test solution.
- Controls: 100 ml growth medium inoculated wth the same volume of algae inoculum culture and without test item.

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: grenn algal
- Strain: Desmidesmus suspicatus
- Source (laboratory, culture collection): Institute of Hydrobiology, Chinese Academy of Science
- Age of inoculum (at test initiation): 3 days

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Test temperature:

22.8-23.4 °C

pH:

7.85-8.25

Nominal and measured concentrations:

nominal concentration: 100 mg/l

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 ml conical glass flasks
- Type (delete if not applicable): capped with air-permeablemembrane
- Fill volume: 100 ml

- Initial cells density: 5x10E3 cell/ml
- No. of vessels per concentration (replicates): 6
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Photoperiod: continous and uniform light
- Light intensity and quality: 4440-8880 Lux for cool white light; Light intensity was maintained within +/- 1.3-1.7 % from the average light intensity , i. e. 4699 lux above the incubation area.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: manual cell counting by microscope


- Range finding study:
Test concentrations: nominal concentration of 10, 100 mg/l:
Results used to determine the conditions for the definitive study: no inhibition of specific growth was observed

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol (3,5-DCP), tested twice a year

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

cell number

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

cell number

Details on results:

The measured TOC concentration (deduced control) in the sample of the test solution at the start of the test was 0.9693 mg/l, and the measured TOC concentration (deduced control) in the sample of the test solution at the end of the test was 0.1284 mg/l. The geometric TOC concentration was 0.3528 mg/l during the test. According to an analysis of the Total Organic Carbon Content in a separate study the carbon content of the test item is 81.0 %. Therefore, the geometric mean measured TOC concentration corresponds to a geometric mean measured test concentration of 0.4356 mg/l.

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- ErC50: 2.10 mg/l

Reported statistics and error estimates:

The result of the two-sided Student t-test indicated that average specific growth rate and yield did not display significant differences(p>0.05) between the control and the test group.

Loading rate (mg/l)	Mean cell concentration Day 3	Mean Specific Growth Rate Day 3	Mean Coefficient of variation	Mean percent inhibition in average specific growth rate	Mean percent inhibition of yield
Control	44.0	1.49	15.7 %	-	-
100 mg/l	45.7	1.50	16.3%	-0.7%	-3.9%

Validity criteria fulfilled:

yes

Conclusions:

According to the results of the test, the 72-hour median effect loading rate for the parameters average specific growth rate (ErL5) and yield (EyL50) of the test item to Desmodesmus subspicatus was both greater than nominal 100 mg/l. The 72-hour no observed effect loading rate (NOEL) was determied to be >= 100 mg/l.

Executive summary:

A growth inhibition study of Guerbet alcohols, C24 -26, branched and cyclic was conducted to algae over a 72 -hour exposure period in a static system. Desmodesmus Subspicatus at initial cell concentrations of 5x10E4 cells/ml was exposed to nominal concentrations of 100 mg/l test substance. No effects on the growth rate or yield were observed. Therefore, the ErC50 and EyC50 were determined to be > 100 mg/l. The NOEC for both growth rate and biomass was >= 100 mg/l.

Description of key information

Experimental data on Guerbet alcohols, C24-26, branched and cyclic show no toxicity to algae up to the limit of solubility.

A growth inhibition study of Guerbet alcohols, C24 -26, branched and cyclic was conducted to algae over a 72 -hour exposure period in a static system. Desmodesmus Subspicatus at initial cell concentrations of 5x10E4 cells/ml was exposed to nominal concentrations of 100 mg/l test substance. No effects on the growth rate or yield were observed. Therefore, the ErC50 and EyC50 were determined to be > 100 mg/l. The NOEC for both growth rate and biomass was >= 100 mg/l.

Studies of the structurally related guerbet alcohols 2 -hexyldecan-1 -ol and 2 -octyldodecan-1 -ol show similar results. For both test substances with even higher water solubility no effects on the growth rate or yiled of algae was observed.

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:

100 mg/L