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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Administrative data

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
28 Aug - 01 Sep 1995
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: GLP guideline study with restrictions (no analytical monitoring)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1995
Report date:
1995

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
other: Annex of EU guideline 92/69/EWG, adopted 1992
Qualifier:
according to guideline
Guideline:
other: VCI concept draft for (acute) aquatic testing of poorly soluble substances, adopted 1994
Principles of method if other than guideline:
The VCI concept schedules a maximum of 4 test steps:
(1) Limit test at nominal 100 mg/L without separation of phases
(2) Limit test at nominal 100 mg/L after separation of insoluble components
(3) Testing at saturation level: 3- to 5-fold saturation concentration and separation of insoluble components
(4) Testing of dilutions of the saturated solution prepared in (3)
GLP compliance:
yes

Test material

Constituent 1
Reference substance name:
Fatty acids, C16-18 and C18-unsatd., iso-Bu esters
EC Number:
284-868-8
EC Name:
Fatty acids, C16-18 and C18-unsatd., iso-Bu esters
Cas Number:
84988-79-4
IUPAC Name:
84988-79-4

Sampling and analysis

Analytical monitoring:
no

Test solutions

Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method 1: 100 mg/L after separation of undissolved material:
111 mg test substance were added to 1 L deionised water and continuously stirred for 24 h using a magnetic stirrer. Insoluble parts of the test substance were separated by filtration through a glass fibre filter pre-treated with 1 M NaOH.
- Method 2: 100 mg/L direct weighing without separation of undissolved material:
After weighing, the test substance solution was incubated for 24 h on a shaker.

Test organisms

Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Source (laboratory, culture collection): Laboratory stock at Henkel KGaA, originally obtained from Universität Göttingen, Institute of Plant Physiology
- Age of inoculum (at test initiation): 3 to 4 days pre-incubation in test medium without test substance

ACCLIMATION
- Culturing media and conditions (same as test or not): same

Study design

Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h

Test conditions

Hardness:
no data
Test temperature:
23 °C
pH:
6.9 - 7.0 at test start
6.8 - 7.2 at test end
Dissolved oxygen:
no data
Nominal and measured concentrations:
Nominal: 0 and 100 mg/L, with and without separation of insoluble test substance components
Details on test conditions:
TEST SYSTEM
- Test vessel: Erlenmeyer flasks
- Size, fill volume: 300 mL, 100 mL
- Initial cells density: 10,000 cells/mL
- Control end cells density: 220,000 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3

GROWTH MEDIUM
- Standard medium used: mineral salt medium following DIN 38412/9
- Detailed composition if non-standard medium was used: no details given

OTHER TEST CONDITIONS
- Sterile test conditions: Bacterial growth was observed in the test series with direct weighing of the test substance.
- Photoperiod: continuous light
- Light intensity and quality: max. 300 lux with daylight spectrum
- Shaking: 120 rpm

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

Results and discussion

Effect concentrationsopen allclose all
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
< 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks on result:
other: without filtration
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
WAF
Basis for effect:
biomass
Remarks on result:
other: with filtration
Details on results:
- Exponential growth in the control (for algal test): yes
- Other: In the test series with direct weighing of the test substance, turbidity of the medium occured due to growth of bacteria
- Effect concentrations exceeded solubility of substance in test medium in part 2 of the study.

Any other information on results incl. tables

Part 1 of the study (without separation of undissolved test substance): Average growth inhibition of 93% (AUC method).

Part 2 of the study (after separation of undissolved test substance): No negative effects at the level of water solubility (< 0.025 mg/L).

Based on these results it can be assumed that the effects occurring in the presence of undissolved test substance components are due to the physical effects of undissolved fractions rather than to systemic toxicity.

Table 1: Cell concentrations after 24, 48 and 72 h of exposure to the test substance

Test Concentration (mg/L)

Cell Concentration (cells/mL)

24 h

48 h

72 h

0

3.0E04

9.0E04

2.2E05

100

without separation

0

2.3E04

3.3E04

100

after separation

2.0E04

1.5E05

3.6E05

Applicant's summary and conclusion