Alcohols, C8-10, ethoxylated, sulfates, ammonium 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:

Feb 25 - Feb 28, 2013

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:

2011

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

The concentration of the test item was analysed in all test solutions sampled at the beginning of the exposure period prior to the addition of the algae and in samples of the algae cultures taken from replicates pooled per test concentration at the end of the exposure period.
Duplicate samples of 750 µL were taken from the pooled replicates, given in 2 mL glas vials and analysed immediately. The retain samples has been stored at -20 °C.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: The highest test concentration (100 mg pure substance/L) was prepared by solving 136.43 mg of the test item (purity 73.3 %) in 1000 mL growth medium and stirring for 2 hours at room temperature. To obtain the other required test concentrations the highest test concentration was serially diluted with growth medium.

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: green algae
- Source (laboratory, culture collection): SAG, Culture Collection of Algae at Pflanzenphysiologisches Institut of the University at Göttingen, Göttingen, Germany
- Method of cultivation: The stock cultures are maintained fulfilling the criteria of the OECD guideline (OECD No. 201).

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

23.0 °C

pH:

7.9 - 9.4

Nominal and measured concentrations:

Nominal test concentrations: control, 0.95, 3.05, 9.77, 31.25, 100 mg/L
Mean measured test concentrations (study initiation): < LOQ, 0.9, 2.79, 9.01, 30.3, 100 mg/L
Mean measured test concentrations (study end): Recovery rates: 84.7 - 100%

Limit of Quantification (LOQ): 0.1 µg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: conical flasks with air-permeable silicone-sponge caps
- Material, size, fill volume: glass, 250 ml, 100 ml
- Initial cells density: 10 000 cells/ml
- Control end cells density: 329.1E+4 cells/ml
- No. of vessels per concentration (replicates): 8
- No. of vessels per control (replicates): 4

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: sterilised synthetic OECD medium prepared with purified water

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Photoperiod: continuously illuminated
- Light intensity and quality: 7310 - 7602 lux

EFFECT PARAMETERS MEASURED:
- Determination of cell concentrations: cell concentrations using an electronic particle counter recorded after 24, 48 and 72

TEST CONCENTRATIONS
- Range finding study: yes
- Test concentrations: 0.75, 3.0, 18 mg/L
- Results used to determine the conditions for the definitive study: growth rate inhibition at 18 mg/L after 72h: 4.4%

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

31.25 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

other: yield

Details on results:

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

Results with reference substance (positive control):

ErC50 (72 h) = 2.42 mg/L

Table 1: Validity criteria for OECD 201.

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.	329	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%	12.4%	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%.	2.6%	yes

 

Table 2:   Growth rate (G) and its inhibition relative to control (% I) as an effect of the test substance, computed from the raw data for test intervals selected

Nominal conc.	0-24 h		0-48 h		0-72 h
[mg/L]	G	% I	G	% I	G	% I
Control	1.676	0.0	1.879	0.0	1.929	0.0
0.954	1.630	2.7	1.831	2.6	1.817	5.8
3.05	1.604	4.3	1.781	5.2	1.801	6.6
9.77	1.608	4.0	1.740	7.4	1.779	7.8
31.3	1.676	0.0	1.794	4.5	1.835	4.9
100	1.495	10.8	1.532	18.5	1.673	13.3

 

Table4:   Measured concentrations of the test item

Nominal conc.	Measured conc. (0 h)		Measured conc. (72 h)
[mg/L]	[mg/L]	% of nominal	[mg/L]	% of initial
Control	< LOQ	-	< LOQ	-
0.954	0.896	93.9	0.808	84.7
3.05	2.79	91.4	2.65	87.0
9.77	9.01	92.2	8.51	87.1
31.3	30.3	97.0	29.4	94.0
100	100	100	96.7	96.7

LOQ was 0.10 µg/L

 

Validity criteria fulfilled:

yes

Remarks:

Please see Table 1 at "Any other information on results incl. tables"

Description of key information

ErC50 (72 h) > 100 mg a.i./L (nominal, OECD 201)

NOErC (72 h): 31.3 mg a.i./L (nominal; OECD 201)

Additional information

The toxicity of the substance to aquatic algae was tested in a GLP guideline study conducted according to OECD 201. Green algae of the species Pseudokirchneriella subcapitata were exposed to nominal test substance concentrations of 0.95, 3.05, 9.77, 31.3, 100 mg a.i./L. The substance concentrations in freshly prepared and from test solutions at the end of the exposure period analytically verified by liquid chromatography (LC) and tandem mass spectrometry detection (LC-MS/MS). The mean measured test concentrations after 72 h were values were within the range of ± 20 %, the nominal concentrations (i.e. <LOQ, 0.81, 2.65, 8.51, 29.4, and 96.7 mg a.i./L). Sterilised synthetic OECD medium prepared with purified water was used as test medium.
Algal cell concentrations were determined after 24, 48 and 72 h in samples taken directly from the test vessels. A slight concentration-dependent inhibition of growth rate and yield was observed. The determined NOErC (72 h) was 31.3 mg a.i./L based on nominal concentrations. The ErC50 (72 h) was >100 mg a.i./L (nominal).