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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:
12 - 15 Jul 1993
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Qualifier:
according to
Guideline:
other: EU-Guideline 92/69 EWG
GLP compliance:
yes
Analytical monitoring:
yes
Vehicle:
no
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Strain: 86.81 SAG
- Source (laboratory, culture collection): originally obtained from Institut für Wasser-, Boden- und Lufthygiene, Berlin. In-house culture
- Age of inoculum (at test initiation): 3 days
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Test temperature:
24 °C +/- 2 °C
pH:
Test start: 7.9 - 8.1
Test end: 7.2 - 8.8
Nominal and measured concentrations:
nominal: 0.7, 1.5, 3, 6, 12 and 24 mg/L
mean measured: 0.93, 1.8, 3.2, 6.3, 13.8 and 24.5 mg/L (based on a-WAS)
Details on test conditions:
TEST SYSTEM
- Test vessel:
- Material, size, headspace, fill volume: Erlenmeyer flasks
- Aeration: yes
- Initial cells density: 20000 cells/mL
- Control end cells density: 730000 cells/mL
- No. of vessels per concentration (replicates): 5
- No. of vessels per control (replicates): 8


GROWTH MEDIUM
- Standard medium used: yes according to EU-Guideline 92/69/EWG


OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Photoperiod: continuous illumination
- Light intensity and quality: approximately 8000 Lux (white)



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



Reference substance (positive control):
no
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
27.7 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Remarks on result:
other: endpoint re-calculated from the data given in the study: endpoint in a-WAS and purity of the test material
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.95 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Remarks on result:
other: endpoint re-calculated from the data given in the study: endpoint in a-WAS and purity of the test material
Details on results:
- Exponential growth in the control (for algal test): yes
- 72h ErC50 based on a-WAS = 27.0 mg/L
Reported statistics and error estimates:
The EC-values were determined by probit transformation of percental growth inhibition values using regression analysis. Based on these values an additional probit analysis according to Cavalli-Sforza were conducted.

Concentration [mg/L]

Cell density (x 104cells/mL)

Test duration

0 h

24 h

48 h

72 h

Control

2

5

18

73

0.93

2

5

19

73

1.8

2

5

17

58

3.2

2

5

16

59

6.3

2

5

16

53

13.8

2

4

12

19

24.5

2

4

13

14

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
30 Aug - 02 Sep 1994
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Qualifier:
according to
Guideline:
EU Method C.3 (Algal Inhibition test)
GLP compliance:
yes
Analytical monitoring:
yes
Vehicle:
no
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Strain: 86.81 SAG
- Source (laboratory, culture collection): Institut für Wasser-, Boden- und Lufthygiene, Berlin and subsequently in-house breeding
- Age of inoculum (at test initiation): 3 days
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Test temperature:
24 +/- 2 °C
pH:
Test start: 8.4 - 8.5
Test end: 7.6 - 9.4
Nominal and measured concentrations:
nominal: 1, 2, 4, 8, 16 and 32 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel:
- Material, size, headspace, fill volume: Erlenmeyer flasks
- Aeration: yes
- Initial cells density: 20000 cells/mL
- Control end cells density: 970000
- No. of vessels per concentration (replicates): 5
- No. of vessels per control (replicates): 8


OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Photoperiod: continuous illumination
- Light intensity and quality: approximately 8000 Lux, white


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

Reference substance (positive control):
no
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
14 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
4.3 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
2 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Reported statistics and error estimates:
From the comparison of the areas under the growth curves, the percentage inhibition rates are calculated for each concentration.
The expect probits for each concentration were calculated by probit transformation of the percentage inhibition rates over the regression line. This probits are the basis for the following probit analysis according to Cavalli-Sforza.

 

Cell number (x 104cells/mL)

Concentration
[mg/L]

Test period (h)

0 h

24 h

48 h

72 h

Control

2

6

25

97

1

2

7

25

93

2

2

8

25

83

4

2

6

23

77

8

2

6

16

49

16

2

4

7

11

32

2

3

4

3

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 Category Approach Justification provided in Section 13
Reason / purpose:
read-across source
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
27.7 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Remarks on result:
other: endpoint re-calculated from the data given in the study: endpoint in a-WAS and purity of the test material
Remarks:
Source, key, 68891-38-3, 1993c
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.95 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Remarks on result:
other: endpoint re-calculated from the data given in the study: endpoint in a-WAS and purity of the test material
Remarks:
Source, key, 68891-38-3, 1993c

Description of key information

ErC50 (72 h) = 14 mg a.i./L (nominal) for Scenedesmus subspicatus (OECD 201)
NOEC (72 h) = 0.95 mg a.i./L (measured) for Scenedesmus subspicatus (OECD 201)

Key value for chemical safety assessment

EC50 for freshwater algae:
14 mg/L
EC10 or NOEC for freshwater algae:
0.95 mg/L

Additional information

For aquatic algae no studies on toxic effects of AES (C12-14, 1-2.5 EO) TEA (CAS 157627-94-6) are available. Therefore, a read-across approach from two similar AES (C12 -14, 2.5EO) mixtures was applied.

Both studies were conducted according to OECD guideline 201 and GLP with Scenedesmus subspicatus as test species. In one study the algae were exposed for 72 hours to AES (C12-14, 1-2.5EO) Na (CAS 68891-38-3), which resulted in an EC50 value of 27.7 mg a.i./L (measured) based on growth rate and a corresponding NOEC of 0.95 mg a.i./L (Sasol, 1993c). In the second study the test organisms were exposed for 72 hours to AES (C12-14, 1-2.5EO) MIPA (CAS 1187742 -72 -8), which resulted in an EC50 value of 14 mg a.i./L (nominal) based on growth rate and a corresponding NOEC of 2 mg a.i./L (nominal) (Sasol, 1999c).