Sorbitan, tridocosanoate

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:

08 -11 Nov 2017

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

Analytical monitoring:

yes

Details on sampling:

Samples of the control and 100 mg/L test concentration were taken after 0 and 72 h.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The weighed test sample of 120 mg and medium of 1200 mL were mixed and stirred with a magnetic stirrer for 48 h to prepare the test solution of 100 mg/L (nominal concentration).
At the start of exposure, the test solution of 100 mg/L exposure level (nominal) was white suspended.

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: green algae
- Strain: ATCC22662
- Source (laboratory, culture collection): American Type Culture Collection

ACCLIMATION
- Acclimation period: pre-culture period of 3 days
- Culturing media and conditions (same as test or not): same

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Test temperature:

23 °C

pH:

7.7-7.8

Nominal and measured concentrations:

Nominal test substance concentration: 100 mg/L
Measured test substance concentration: < LOD of 0.521 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: glass flasks (300 mL)
- Type (delete if not applicable): covered with gas-permeable Silicosen (R)
- Fill volume: 100 mL
- Initial cells density: 7500 cells/mL
- No. of vessels per concentration (replicates):6
- No. of vessels per control (replicates): 6


GROWTH MEDIUM
- Standard medium used: yes

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

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: no
- Photoperiod: continous illumination
- Light intensity and quality: 91-92 μmol/m²s


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: Particle counter; Model COULTER Z2 (Beckman Coulter, Inc., Instrument No.CC-004)
- Chlorophyll measurement: every 24 h; Chlorophyll fluorescence with Spectrophotofluorometer; Model RF-6000

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

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:

NOEC

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

The concentrations of test item in the test solutions during the exposure were below the determination limit (< 0.557 mg/L ), indicating that the concentration of dissolved test item in medium was not clarified. However, no effect was found in the definitive study. Therefore, it was decided that the test item had no adverse effect on the test organisms at around the solubility in medium.

Results with reference substance (positive control):

Test period; 31. Juli - 3. Aug., 2017
ErC50 (0-3 d); 1.1 mg/L

Table 1: Growth inhibition .

Nominal concentration [mg/L]	Sample No.	Growth rate (0 - 3 d)	Growth inhibition rate [%]
Control	A	1.35	-
	B	1.43	-
	C	1.58	-
	D	1.56	-
	E	1.46	-
	F	1.49	-
	Mean	1.48 (SD 0.0851)	-
100	A	1.58	- 7.2
	B	1.57	- 6.1
	C	1.58	- 6.7
	D	1.59	- 7.8
	E	1.65	-11
	F	1.62	- 9.9
	Mean	1.60 (SD 0.0309)	-8.2 (SD 2.1)

Table 2: 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.	≥ 56	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%	9.8%	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%.	5.8%	yes

Validity criteria fulfilled:

yes

Remarks:

For further details please refer to “Any other information on results incl. tables”

Description of key information

EC50 (72 h) >100 mg/L (nominal)

NOEC (72 h)≥ 100 mg/L (nominal).

Additional information

The acute toxicity of the test substance to aquatic algae was tested in a study following OECD guideline 201 (GLP). Green algae of the species Pseudokirchneriella subcapitata were exposed to a nominal test substance concentration of 100 mg/L in a limit test. The nominal concentration was analytically verified by HPLC. The test substance concentration was below the determination limit of the method of 0.521 mg/L reflecting the very low water solubility of the substance of 0.525 mg/L at 20 °C, pH 5.9. During the 72 hour exposure period no significant growth inhibition was observed.  The reported EC50 (72 h) is >100 mg/L (nominal). The NOEC (72 h) is ≥ 100 mg/L (nominal).

Based on the results acute toxic effects on aquatic algae are not expected within the range of water solubility.