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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:
Not yet reported
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.3 (Algal Inhibition test)
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
yes
Vehicle:
no
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
>= 32 - <= 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
loading rate WAF
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
NOELR
Effect conc.:
< 1 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
loading rate WAF
Basis for effect:
growth rate
Details on results:
- Biologically relevant growth rate and yield inhibition (i.e. > 10 %) was recorded at all test concentrations, except for the WAF prepared at a loading rate of 1.0 mg/L.
- A dose-related increase of growth rate and yield inhibition was measured at the loading rate of 3.2 and higher, reaching 85 % growth rate inhibition and 100 % yield inhibition at the WAF prepared at a loading rate of 100 mg/L.
- Based on these results, the NOEC for both growth rate and yield inhibition is expected to lie below a loading rate of 1.0 mg/L.

PERCENTAGE INHIBITION OF GROWTH RATE DURING THE FINAL TEST

Test item loading rate WAF (mg/L)

Mean

Standard deviation

n

% inhibition

Control

1.856

0.0091

6

-

1.0

1.603

0.0533

3

14

3.2

1.832

0.0108

3

1.3

10

1.170

0.0674

3

37

32

1.147

0.0288

3

38

100

0.276

0.0133

3

85

 

PERCENTAGE INHIBITION OF YIELD DURING THE FINAL TEST

Test item loading rate WAF (mg/L)

Mean

Standard deviation

n

% inhibition

Control

260.8

7.09

6

-

1.0

122.8

20.42

3

53

3.2

242.5

7.83

3

7.0

10

32.9

7.18

3

87

32

30.3

2.67

3

88

100

1.3

0.09

3

100

ANALYTICAL RESULTS

Sampling time (hours)

Date of sampling

Date of analysis

Loading rate (mg/L)

Concentration analysed (mg/L)

Relative to initial (%)

Note

0

14 May 2018

23 May 2018

0

0.0020

Not applicable

1

0

14 May 2018

23 May 2018

1.0

0.0841

Not applicable

-

0

14 May 2018

23 May 2018

3.2

0.0050

Not applicable

1

0

14 May 2018

23 May 2018

10

0.132

Not applicable

-

0

14 May 2018

23 May 2018

10

0.134

Not applicable

ZA

0

14 May 2018

23 May 2018

32

0.126

Not applicable

-

0

15 May 2018

23 May 2018

100

0.520

Not applicable

-

24

15 May 2018

23 May 2018

0

0.0017

84

1

24

15 May 2018

23 May 2018

1.0

0.0016

1.9

1

24

15 May 2018

23 May 2018

3.2

< 0.000057

< 1.1

2

24

15 May 2018

23 May 2018

10

0.0025

1.9

1

24

15 May 2018

23 May 2018

10

0.0037

2.8

1 + ZA

24

15 May 2018

23 May 2018

32

0.0020

1.6

1

24

15 May 2018

23 May 2018

100

0.0436

8.4

-

72

17 May 2018

23 May 2018

0

0.0016

78

1

72

17 May 2018

23 May 2018

1.0

< 0.000057

< 0.07

2

72

17 May 2018

23 May 2018

3.2

0.0014

29

1

72

17 May 2018

23 May 2018

10

0.0015

1.2

1

72

17 May 2018

23 May 2018

10

< 0.000057

< 0.04

ZA + 2

72

17 May 2018

23 May 2018

32

0.0016

1.2

1

72

17 May 2018

23 May 2018

100

0.0019

0.4

1

ZA = Without Algae

1 = Estimated value, calculated by extrapolation of the calibration curve.

2 = Not detected. The limit of detection of the method was determined to be 0.057 µg/L taking a dilution factor of 2 into account.

Validity criteria fulfilled:
yes
Conclusions:
The 72-hour EC50 values are expressed in terms of loading rates. Based on growth rate, the EC50 (72 h) value is considered to lie between 32 and 100 mg/L loading rate WAF. Based on yield, the EC50 (72 h) value is considered to lie between 3.2 and 10 mg/L loading rate WAF. The NOEC for both growth rate and yield inhibition is predicted to be < 1.0 mg/L.
Executive summary:

GUIDELINE

A study was performed to assess the effect of the test item on the growth of the green alga Pseudokirchneriella subcapitata. The method followed was designed to be compatible with the OECD Guidelines for Testing of Chemicals (2006) No 201, "Freshwater Alga and Cyanobacteria, Growth Inhibition Test" referenced as Method C.3 of Commission Regulation (EC) 761/2009.

METHODS

For the final test, Water Accommodated Fractions (WAFs) were individually prepared at loading rates of 1.0, 3.2, 10, 32 and 100 mg/L. One hour of gentle magnetic stirring was applied to accelerate dissolution of test item in test medium. The obtained mixtures were allowed to settle for a period of approximately three hours. Thereafter, the WAFs were collected by means of siphoning over glass wool and used as test concentrations. At the end of the preparation procedure, all test solutions were clear and colorless.

RESULTS

Biologically relevant growth rate and yield inhibition (i.e. > 10 %) was recorded at all test concentrations, except for the WAF prepared at a loading rate of 1.0 mg/L. A dose-related increase of growth rate and yield inhibition was measured at the loading rate of 3.2 and higher, reaching 85 % growth rate inhibition and 100 % yield inhibition at the WAF prepared at a loading rate of 100 mg/L. Based on these results, the NOEC for both growth rate and yield inhibition is expected to lie below a loading rate of 1.0 mg/L.

CONCLUSION

The 72-hour EC50 values are expressed in terms of loading rates. Based on growth rate, the EC50 (72 h) value is considered to lie between 32 and 100 mg/L loading rate WAF. Based on yield, the EC50 (72 h) value is considered to lie between 3.2 and 10 mg/L loading rate WAF. The NOEC for both growth rate and yield inhibition is predicted to be < 1.0 mg/L.

Description of key information

The 72-hour EC50 values are expressed in terms of loading rates. Based on growth rate, the EC50 (72 h) value is considered to lie between 32 and 100 mg/L loading rate WAF. Based on yield, the EC50 (72 h) value is considered to lie between 3.2 and 10 mg/L loading rate WAF. The NOEC for both growth rate and yield inhibition is predicted to be < 1.0 mg/L (OECD 201 and EU Method C.3).

Key value for chemical safety assessment

EC50 for freshwater algae:
32 mg/L
EC10 or NOEC for freshwater algae:
1 mg/L

Additional information

GUIDELINE

A study was performed to assess the effect of the test item on the growth of the green alga Pseudokirchneriella subcapitata. The method followed was designed to be compatible with the OECD Guidelines for Testing of Chemicals (2006) No 201, "Freshwater Alga and Cyanobacteria, Growth Inhibition Test" referenced as Method C.3 of Commission Regulation (EC) 761/2009.

METHODS

For the final test, Water Accommodated Fractions (WAFs) were individually prepared at loading rates of 1.0, 3.2, 10, 32 and 100 mg/L. One hour of gentle magnetic stirring was applied to accelerate dissolution of test item in test medium. The obtained mixtures were allowed to settle for a period of approximately three hours. Thereafter, the WAFs were collected by means of siphoning over glass wool and used as test concentrations. At the end of the preparation procedure, all test solutions were clear and colorless.

RESULTS

Biologically relevant growth rate and yield inhibition (i.e. > 10 %) was recorded at all test concentrations, except for the WAF prepared at a loading rate of 1.0 mg/L. A dose-related increase of growth rate and yield inhibition was measured at the loading rate of 3.2 and higher, reaching 85 % growth rate inhibition and 100 % yield inhibition at the WAF prepared at a loading rate of 100 mg/L. Based on these results, the NOEC for both growth rate and yield inhibition is expected to lie below a loading rate of 1.0 mg/L.

CONCLUSION

The 72-hour EC50 values are expressed in terms of loading rates. Based on growth rate, the EC50 (72 h) value is considered to lie between 32 and 100 mg/L loading rate WAF. Based on yield, the EC50 (72 h) value is considered to lie between 3.2 and 10 mg/L loading rate WAF. The NOEC for both growth rate and yield inhibition is predicted to be < 1.0 mg/L.