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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Reference
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From January 19, 2018 to March 21, 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reference:
Composition 0
Qualifier:
according to
Guideline:
OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)
GLP compliance:
yes
Test material information:
Composition 1
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
- Source: Canadian Phycological Culture Center
Test type:
static
Water media type:
freshwater
Total exposure duration:
72 h
pH:
6.6-7.9
Nominal and measured concentrations:
Nominal concentrations: 0, 6.25, 12.5, 25, 50, and 100 mg/L
Details on test conditions:
- Test vessel: 250 mL Erlenmeyer flasks
- Test volume: 50 mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6
- Light intensity and quality: 5769-6097 lux
Reference substance (positive control):
yes
Remarks:
Zinc sulphate heptahydrate (CAS No. 7446-20-0)
Duration:
72 h
Dose descriptor:
EC50
Remarks:
for specific growth rate (ErC50)
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Duration:
72 h
Dose descriptor:
EC50
Remarks:
for Cell Yield (EyC50)
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Results with reference substance (positive control):
72-h EC50 of zinc sulphate heptahydrate was 0.079 mg/L Zn2+

Table 1. Summary of Cell Counts in each 24-h period for the P. subcapitata Growth Inhibition Test

Nominal Concentration (mg/L)

Mean Cell Counts (×104cells/mL)

0-h

24-h

48-h

72-h

Negative Control (0)

0.97

2.8

16.0

87.3

6.25

0.97

2.0

14.9

83.3

12.5

0.97

1.3

17.0

83.0

25

0.97

2.7

18.5

84.5

50

0.97

1.8

15.4

84.8

100

0.97

2.3

16.2

80.2

Table 2. Mean Cell Yield and Specific Growth Rate

Nominal Concentration (mg/L)

Mean Yield (x104cells/mL)

SD

% CV

Mean SGR

SD

% CV

Negative Control (0)

86.3

15.2

17.7

1.50

0.05

3.48

6.25

82.0

22.6

27.6

1.48

0.09

5.96

12.5

82.0

11.0

13.4

1.48

0.05

3.12

25

83.7

9.7

11.6

1.49

0.04

2.67

50

83.7

23.7

28.3

1.48

0.09

5.89

100

79.0

17.4

22.0

1.47

0.07

4.70

SGR: Specific Growth Rate

SD: Standard Deviation

% CV: Percent Coefficient of Variation

 

Table 3. Summary of the Mean Inhibition in Specific Growth Rate (%) and in Cell Yield (%) for the P. subcapitata Growth Inhibition Test

Nominal Concentration (mg/L)

Mean Inhibition in Yield (%)

Mean Inhibition inSpecific Growth Rate (%)

Negative Control (0)

N/A

N/A

6.25

4.6

1.33

12.5

5.0

1.02

25

3.2

0.58

50

2.9

0.93

100

8.2

1.96

Table 4. Summary of the Test Endpoints Values (Nominal Concentration)

Endpoint Assessment

Cell Yield

Specific Growth Rate

72-h EC50 

(Confidence Limits) (mg/L)

>100

(N/A)

>100

(N/A)

NOEC / LOEC

100 / >100

100 / >100

Validity criteria fulfilled:
yes
Conclusions:
According to OECD 201 test method, the ErC50 and the EyC50 of I850 was >100 mg/L and >100 mg/L respectively.
Executive summary:

This test using the procedures outlined in the Maxxam Study Plan for TOX1737 which is based on the SOP for the OECD 201 (BBY2SOP-00016) and OECD 201 (OECD, 2011). The results of this OECD 201 test for I850 show that test validity criteria was met. In the alga growth inhibition test, the test article concentrations applied were 6.25, 12.5, 25, 50 and 100 mg/L. Under the test conditions, the ErC50and the EyC50 of I850 was >100 mg/L and >100 mg/Lrespectively.

Description of key information

Respectively, the ErC50 and the EyC50 of I850 was >100 mg/L and >100 mg/L for Pseudokirchneriella subcapitata (OECD TG201).

Key value for chemical safety assessment

EC50/LC50 for freshwater algae:
100 mg/L

Additional information

The biomass in the control cultures have increased exponentially by a factor of at least 16 within the 72-hour test period. The mean coefficient of variation for specific growth rates (Day 0-1, Day 1-2, Day 2-3, and Day 0-3) in the control cultures were not exceed 35%. The coefficient of variation of mean specific growth rates over the test period in replicate control cultures was not exceed 7%. This test validity criteria was met. The variation in the pH values in the beginning and end of the tests was less than 1.5 units. Under the test conditions, the ErC50 and the EyC50 of I850 was >100 mg/L and >100 mg/L respectively.