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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:
17 - 21 Sep 1990
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1991
Report date:
1991

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Version / remarks:
1984
Deviations:
yes
Remarks:
extended to 96 h
GLP compliance:
yes

Test material

Constituent 1
Chemical structure
Reference substance name:
3,7-bis(diethylamino)phenoxazin-5-ium acetate
EC Number:
279-349-8
EC Name:
3,7-bis(diethylamino)phenoxazin-5-ium acetate
Cas Number:
79916-07-7
Molecular formula:
C20H26N3O.C2H3O2
IUPAC Name:
3,7-bis(diethylamino)phenoxazin-5-ium acetate
Test material form:
solid: particulate/powder

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
Analyses of the test article were performed in duplicate in the test concentrations 6.25, 25 and 100 µg/L and the control: a part of the freshly prepared test media (without algae) were sampled and analysed. For the determination of the stability of the test article under test conditions, a part of the test media were incubated under the same conditions as in the test itself (but without algae) and analysed after the end of the test (96 hours).

Test solutions

Vehicle:
no
Details on test solutions:
A stock solution was prepared by dissolving the test article in test medium (1 g/L). The stock solution was diluted in a series of sequential dilutions. The final nominal concentrations in the test media were: 6.25, 12.5, 25, 50 and 100 µg/L and a control without any additions.

Test organisms

Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
The test organism used for the study was Desmodesmus subspicatus CHODAT, Strain No. 8681 SAG, supplied by the Sammlung von Algen-
kulturen, Pflanzenphysiologisches Institut der Universität Göttingen

The algae were grown in the laboratories of RCC under standardized conditions according to the OECD Guideline No. 201

Study design

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
96 h
Remarks on exposure duration:
extended from 72 to 96 h

Test conditions

Test temperature:
20.5 - 23.0°C
pH:
8.0 - 8.5
Nominal and measured concentrations:
Nominal: 0 (control), 6.25, 12.5, 25, 50, 100 µg/L
Measured (geometric mean): 0 (control), 12.17 (195%, inaccuracy at low concentrations), 24.4 (98%), 88.8 (89%)
Details on test conditions:
TEST SYSTEM
- Test vessel: Erlenmayer flasks
- Type (delete if not applicable): open (permeable plugs)
- Material, size, headspace, fill volume: glass, 300 mL total volume, 150 mL fill volume
- Initial cells density: 10,000
- Control end cells density: 1,893,600 (189-fold)
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: no
- Photoperiod: continuous
- Light intensity and quality: 8000 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: electronic particle counter

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2
Reference substance (positive control):
yes
Remarks:
potassium dichromate

Results and discussion

Effect concentrationsopen allclose all
Key result
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
> 0.013 - < 0.025 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
0.049 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% CI: 0.046 - 0.054 mg/L
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
0.043 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% CI: 0.040 - 0.047 mg/L
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
0.027 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks:
AUC
Remarks on result:
other: 95% CI: 0.025 - 0.029 mg/L
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
0.023 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks:
AUC
Remarks on result:
other: 95% CI: 0.021 - 0.025 mg/L
Details on results:
The toxicity in the lowest nominal concentration was higher than in the second lowest. Also, the analytical verification in the lowest test concentration was not reliable (ca. 200% recovery). Therefore, the lowest concentration was disregarded for the EC10 determination.

189-fold increase of cell number in negative control
Results with reference substance (positive control):
Not reported

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The test item was found to be acutely and chronically toxic to freshwater green algae. The 72-h ErC10 was found to be between 0.016 and 0.025 mg/L, the 72-h ErC50 was determined at 0.049 mg/L (nominal, analytically verified).