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Toxicity to aquatic algae and cyanobacteria

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Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
Please refer to the analogue justification attached to IUCLID section 13.
Reason / purpose for cross-reference:
read-across source
Duration:
72 h
Dose descriptor:
EL10
Effect conc.:
> 13 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
WAF
Basis for effect:
cell number
Remarks on result:
other: Key, source, CAS 16958-92-2, Exxon, 1997, S. subspicatus 72 h, RL2
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
08 - 11 Aug 1997
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
Analytical purity is not given. No NOEC value is derived. No growth curves are shown.
Qualifier:
according to guideline
Guideline:
ISO 8692 (Water Quality - Fresh Water Algal Growth Inhibition Test with Scenedesmus subspicatus and Selenastrum capricornutum)
Deviations:
no
GLP compliance:
not specified
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: The substance was dispersed mechanically with help of a homogenizer (Ultra-turrax from Janke & Kunkel, Stauffen im Breisgau, Germany) at 10000 rpm for 2 minutes. It was then left to stand for 24 h at 20 °C and subsequently filtered (filter type: 589 Blue ribbon from Schleicher & Schüll, Dassel, Germany, pore size: 2.2 µm).
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Common name: green algae
- strain: SAG 86.81
- Source: laboratory bred obtained from Pflanzenphysiologisches Institut, Universität Göttingen, Germany
- Age of inoculum (at test initiation):
- Method of cultivation: The algae were hold in a stock culture under permanent light. The algae were transferred into fresh stock solution every week.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Test temperature:
22 ± 1 °C
pH:
not specified (it is stated that the pH of control did not deviate more than 1.5 during the test period)
Nominal and measured concentrations:
Nominal: 13, 130, 1300 and 13000 mg/L loading rate
Details on test conditions:
TEST SYSTEM
- Initial cells density: 10000 cells/mL
- Control end cells density: 1680000 cells/mL
- No. of vessels per concentration: 2
- No. of vessels per control: 2

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: according to guideline

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Photoperiod: continuously light
- Light intensity and quality: 140 up to 160 µE/m2*s
- The test vessels were shaken at 100 rpm throughout the test.

EFFECT PARAMETERS MEASURED: Cell number was counted after 72 h test duration.
- Determination of cell concentrations: not specified
Reference substance (positive control):
no
Duration:
72 h
Dose descriptor:
EL0
Effect conc.:
>= 13 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
(WAF)
Basis for effect:
cell number
Duration:
72 h
Dose descriptor:
EL10
Effect conc.:
> 13 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
(WAF)
Basis for effect:
cell number
Details on results:
- Exponential growth in the control (for algal test): yes/no
- Observation of abnormalities: no

Description of key information

EL50 (72 h) > 13000 mg/L (nominal, WAF); NOEL (72 h) ≥ 13000 mg/L; Scenedesmus subspicatus (ISO 8692); read-across

Key value for chemical safety assessment

Additional information

Experimental studies investigating toxic effects of the target substance Fatty acids, C18-unsaturated, 1,6 Hexanediol Diester on aquatic algae are not available. Thus, in accordance with Regulation (EC) No 1907/2006 Annex XI, 1.5 a read across to the structurally related source substance Bis(tridecyl) adipate (CAS 16958-92-2) was conducted to fulfill the data requirements according to Annex VII. In this case of read-across, the best suited (highest degree of structural similarity, nearest physico-chemical properties) read-across substance was used for the assessment. This read-across is justified in detail within the analogue justification in IUCLID Section 13.

The toxicity of Bis(tridecyl) adipate (CAS 16958-92-2) to freshwater algae was tested according to ISO guideline 8692 using Scenedesmus subspicatus as test organism. Filtered test item solutions of loading rates between 13 and 13000 mg/L were tested. A reduction of the cell numbers was not observed. The effect concentrations were based on the cell numbers. The determined EL50 (72 h) and EL10 (72 h) were > 13000 mg/L (nominal, WAF). The 72 h-NOEL was determined to be ≥ 13000 mg/L. Based on the available data for the read across substance and the very low water solubility (<0.57 µg/L at 20°C, pH 6.3) of the target substance toxic effects of Fatty acids, C18-unsaturated, 1,6 Hexanediol Diester on algae are not expected.