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Diss Factsheets

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:
other information
Study period:
2004
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Comparable to guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2004

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
EU Method C.3 (Algal Inhibition test)
Deviations:
no
Principles of method if other than guideline:
Method is in most parts equivalent to the OECD TG 210 Alga, Growth inhibition test.
GLP compliance:
yes

Test material

Constituent 1
Chemical structure
Reference substance name:
2-chlorobenzothiazole
EC Number:
210-415-0
EC Name:
2-chlorobenzothiazole
Cas Number:
615-20-3
Molecular formula:
C7H4ClNS
IUPAC Name:
2-chloro-1,3-benzothiazole
Details on test material:
no purity specified

Sampling and analysis

Analytical monitoring:
yes

Test solutions

Vehicle:
no
Details on test solutions:
Preparation of stock solution (50.3 mg/L)
- test substance was weighed into water
- 60 s at 8000 rpm with an ultra-turrax
- stirred for 24 h on a magnetic stirrer
- finally filtered

Test organisms

Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
Desmodesmus subspicatus reported as Scenedesmus subspicatus

Study design

Test type:
static
Water media type:
freshwater
Limit test:
no

Test conditions

Test temperature:
21-25 °C
pH:
without adjustment of pH. The pH is measured at the beginning of the test (0 h) and at its end (72 h).
Dissolved oxygen:
as oxygen is formed during photosynthesis, no oxygen measured
Salinity:
freshwater
Nominal and measured concentrations:
Stability of the test substance was verified by HPLC at 0 and 72 h. Recovery rates of the test substance (% of nominal):
- 78.8 - 98 at 0 h,
- 66.3 - 90 at 72 h
- Nominal test concentrations: 0.05, 0.11, 0.24, 0.53, 1.17, 2.58, 5.67, 12.47 and 27.44 mg/L without adjustment of pH
Details on test conditions:
- Algal inoculum about 10E+04 cells/ml initial cell density
- 300 ml Erlenmeyer flasks with stoppers as test vessels
- Lighting 60-120 µE m-2 s-1
- Experimental design: 9 test concentrations plus control, 3 replicates per concentration, 6 replicates per control, highest test concentration without algae

Results and discussion

Effect concentrationsopen allclose all
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
5.75 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks on result:
other: 4.50-7.28 mg/L
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
2.29 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
5.07 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
9.64 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
cell number
Remarks on result:
other: 9.06-10.25 mg/L
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
2.29 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
cell number
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
5.07 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
cell number
Reported statistics and error estimates:
The 72 h-EC50 values are calculated or read from the concentration/percentage response curve.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The EC50 of the substance is 9.64 mg/L (nominal) in a 72 h algae growth test according to Directive 92/69/EEC, C.3 with Desmodesmus subspicatus. The NOEC based on biomass growth (b) was identical to the based on population density growth (r) NOEC = 2.29 mg/L