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Toxicity to aquatic algae and cyanobacteria

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Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
02 May - 05 May 1995
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EU Method C.3 (Algal Inhibition test)
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
- Concentrations: all concentrations except stock solution
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: 2.55 g test material/L VE-water (corresponds to 1 g/L)
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Common name: Scenedesmus subspicatus
- Strain: 86.81 SAG
- Source : in-house culture, originally obtained from Institut für Wasser-, Boden- und Lufthygiene, Berlin, Germany
- Age of inoculum: 3 days


Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Post exposure observation period:
not relevant
Test temperature:
24.0 - 24.2 °C
pH:
Test start: 7.2-8.1
Test end: 7.7-9.4
Nominal and measured concentrations:
Nominal: 0, 1.2, 3.0, 7.5, 20, 50, 125 and 300 mg/L
Measured (geometrical mean) values have a deviation < 20% and nominal values were used
Details on test conditions:
TEST SYSTEM
- Test vessel: Erlenmeyer flask
- Aeration: sterile aeration
- Initial cells density: 2*10E4 cells/mL
- Control end cells density: 106000 cells/mL (approximation - read from graph)
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Photoperiod: 24 hours light
- Light intensity and quality: 8000 lux

EFFECT PARAMETERS MEASURED: cell growth and growth rate after 0, 24, 48 and 72 h
- Determination of cell concentrations: spectrophotometer, 685 nm


Reference substance (positive control):
no
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
3 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
11 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
2.7 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
9.3 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
biomass
Details on results:
- Exponential growth in the control: yes

Reported statistics and error estimates:
Determination of EC values: probit transformation with procentual inhibition values and regression analysis
Probit analysis according to Cavalli-Sforza (1972).

At the highest test concentration the turbidity falsified the results. Thus, it was not included in the evaluation.

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
30 Jan -02 Feb 1995
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EU Method C.3 (Algal Inhibition test)
GLP compliance:
yes
Analytical monitoring:
yes
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: 1.68 g test substance were dissolved in 1L VE-water
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Common name: Scenedesmus subspicatus
- Strain: CHODAT 86.81 SAG
- Source (laboratory, culture collection): Institut für Wasser-, Boden- und Lufthygiene, Berlin, Germany
- Age of inoculum (at test initiation): 3 days
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Post exposure observation period:
not applicable
Test temperature:
22.1-22.3 °C
pH:
Begin: 8.2-8.3
End: 7.8-9.4
Nominal and measured concentrations:
Nominal: 0, 0.6, 1.25, 2.5, 5, 10 and 20 mg/L (concentration of active ingredient)
Measured: 0.12, 0.65, 1.2, 2.3, 4.6, 9.7 and 20 mg/L (0 hours, concentration of active ingredient)
Measured: 0.0, 0.61, 0.87, 1.8, 3.4, 12 and 17 mg/L (72 hours, concentration of active ingredient)
Details on test conditions:
TEST SYSTEM
- Test vessel: Erlenmeyer flasks
- Aeration: sterile aeration
- Renewal rate of test solution (frequency/flow rate): none
- Initial cells density: 20,000 cells/mL
- Control end cells density: 1,040,000 cells/mL
- No. of vessels per concentration (replicates): 5
- No. of vessels per control (replicates): 5


OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Photoperiod: 24 hours
- Light intensity and quality: 8000 Lux, white


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: with spectrophotometer at at 685 nm


TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2
Reference substance (positive control):
no
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 20 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
5.4 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.6 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
12 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
2 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
biomass
Details on results:
- Exponential growth in the control (for algal test): yes
Reported statistics and error estimates:
Probit analysis according to Cavalli-Sforza (1972)
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:
Refer to the Category Approach Justification document provided in IUCLID6 Section 13.
Reason / purpose for cross-reference:
read-across source
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
3 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Remarks on result:
other:
Remarks:
Source, key, 90583-18-9, 1996
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
11 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Remarks on result:
other:
Remarks:
Source, key, 90583-18-9, 1996
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
2.7 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
biomass
Remarks on result:
other:
Remarks:
Source, key, 90583-18-9, 1996
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
9.3 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
biomass
Remarks on result:
other:
Remarks:
Source, key, 90583-18-9, 1996

Description of key information

72h EC50 (Desmodesmus subspicatus; growth rate) = 11 mg/L (nominal concentration, EU Method C.3)
72h NOEC (Desmodesmus subspicatus; growth rate) = 3 mg/L (nominal concentration, EU Method C.3)

Key value for chemical safety assessment

EC50 for freshwater algae:
11 mg/L
EC10 or NOEC for freshwater algae:
3 mg/L

Additional information

Since no reliable aquatic algae test is available for C12-14AS NH4 (CAS 90583-11-2), in accordance to Regulation (EC) 1907/2006 Annex XI, 1.5, a read-across to other structurally related category member was conducted. Read-across data from the following substances were used C12-14AS TEA (CAS 90583-18-9) and C12-14AS Na (CAS 85586-07-8). Toxicity of alkyl sulfates is dependent on the carbon chain length and the influence of the counter ion can be neglected.

The key study investigating toxic effects of C12-14AS TEA (CAS 90583-18-9) to freshwater algae Desmodesmus subspicatus was performed according to EU Method C.3 and GLP principles (Scholz 1996). Growth inhibition caused by the test substance was determined after 24, 48 and 72 h of exposure under static conditions to seven test concentrations up to 300 mg/L as anionic active substance (nominal values in agreement with the measured values). The results show that the 72-hour EC50 value for growth rate was 11 mg a.i./L for growth rate and 9.3 mg a.i./L for biomass (nominal concentrations). The NOEC value for growth rate was determined to be 3 mg a.i./L (nominal concentration). Composition of carbon chains of the tested category member C12-14AS TEA (CAS 90583-18-9) is the same as of C12-14AS NH4 (CAS 90583-11-2). Due to structural and property similarity with the tested category member, the 72-hour EC50 value for of 11 mg/L and NOEC of 3 mg/L (both for growth rate) is considered as a reliable for C12-14AS NH4 (CAS 90583-11-2).

Additionally, toxicity of C12-14AS Na (CAS 85586-07-8) to aquatic algae was investigated in the GLP-compliant study with Desmodesmus subspicatus according to EU Method C.3 (Scholz 1995). Algae were exposed to six test concentrations up to 20 mg/L (nominal concentration corresponding to 17 mg/L of measured concentration). The study resulted in the 72-hour EC50 value for growth rate of above 20 mg a.i./L (nominal concentration). The EC10 (72 h) for growth rate was 5.4 mg a.i./L (nominal concentration).