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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:
2008-09-25 - 2009-01-30
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: The study was conducted according to an internationally accepted guideline. All study parameters are based on the specific guideline.
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Details on sampling:
Concentrations of N-[3(5)-Methyl-1H-pyrazol-1-yl-methyl]acetamide as the active ingredient of P 70/05/S-4 in the test solution at the start of the test (0 h) and at the end of the test (72 h) were analysed.
Vehicle:
no
Details on test solutions:
The test item was dissolved directly in test medium.
The test solution was prepared in the following way:
- 200.01 mg P 70/05/S-4 were weighed and filled with test medium up to 1000 mL (= stock solution A, containing 200.01 mg P 70/05/S-4/L)
- 499.98 mL stock solution A were filled up to approximately 990 mL with test medium
- 5 mL algal inoculum (measured 100 x 104 cells/mL) were added and filled up to 1000 mL with test medium to reach an initial biomass (cell density) of about 5 x 103 cells/mL and the required test item concentration in the final test solution (100.0 mg test item/L)
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
Test organism: freshwater green algae - Desmosdesmus subspicatus HILSE
Origin of the test organism: purchased from "Albrecht-von-Haller-lnstitut für Pflanzen-wissenschaften, Experimentelle Phykologie und Sammlung von Algenkulturen" at the University of Göttingen, Germany, in January 2008, strain: 86.81 SAG (further cultivation in the test facility)
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Test temperature:
22.9-25.3 °C
pH:
7.87- 8.12
Nominal and measured concentrations:
During the exposure period of 72 hours the test concentration for P 70/05/S-4 remained within a range of 101 to 103 % of the nominal value at the start (0 hours) and at the end (72 hours) of the experiment. The test concentration was found within ± 20 % of nominal throughout the test. Therefore, all results are based on the nominal concentrations.
Details on test conditions:
Growth and test medium: OECD-medium (after ISO 20079) according to OECD 201 (2006)
Breeding: glass flasks with 100 mL growth medium (OECD-medium) kept at 24 ± 2 C with constant illumination continuous universal white-type fluorescent light (400-700 nm) intensity, approx. 9000 Ix
Conditions: cultures in logarithmic growth phase under sterile conditions
Culturing conditions: axenic stock cultures grew in culturing vessels for 4 days prior to test initiation; cultivation was performed in glass flasks with the medium described above; algae were kept at the same temperature and light conditions as in the test itself

Test vessel: 250 mL Erlenmeyer flask with air-permeable stoppers

Vessel volume : test volume: 2.5 :1 (250 mL test vessel: 100 mL test volume)

Initial biomass: 5 x 10^3 cells/mL in each replicate

Number of treatment groups: 2

Number of replicates (= test vessel): control group: 6 + 1 (for analysis and retain specimen)

treated group: 6 + 1 (for analysis and retain specimen)
Illumination: continuous uniform white-type fluorescent light (400-700 nm) intensity: approx. 9000 Ix (constant illumination)

Reference substance (positive control):
yes
Remarks:
potassium dichromate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: yield inhibition
Results with reference substance (positive control):
To verify the sensitivity of the test system, the reference item potassium dichromate is routinely tested at concentrations of 0.125, 0.25, 0.5, 1.0 and 2.0 mg a.i./L in a separate study.
The EC50 values for the average specific growth rate and yield (biomass increase) determined in the most recent study (BioChem project No.: AA-R 08 10 48 001 W) were 1.065 and 0.493 mg a.i./L.

Biomass determined at 24, 48 and 72 hours after start of the test

Treatment group

Biomass (x 104cells/mL)

mg P 70/05/S-4/L nominal

Replicate

24h

48h

72h

Control (test medium)

1

2

3.25 3.50

13.75 15.25

46.25 44.50

 

3

3.50

18.00

50.50

 

4

3.50

21.50

45.50

 

5

3.50

24.00

49.00

 

6

3.50

13.25

49.00

 

mean

3.46

17.63

47.46

 

SD

0.10

4.37

2.37

 

cv%

2.95

24.81

4.99

100.0

1

2

3.50 3.00

18.00 19.25

48.25 49.25

 

3

3.50

20.00

49.00

 

4

3.50

18.50

44.75

 

5

3.50

17.00

47.50

 

6

3.25

15.75

53.50

 

mean

3.38

18.08

48.71

 

SD

0.21

1.54

2.85

 

cv%

6.20

8.51

5.86

Percentage inhibition of average specific growth rate:

Treatment group

% Inhibition of average specific growth rate

mg P 70/05/S-4/L nominal

0 - 24h

0 - 48h

0 - 72h

Control (test medium)

0

0

0

100.0

1.33

0

0

During the exposure period of 72 hours, no inhibition of the average specific growth rate at the tested concentration of 100 mg P 70/05/S-4/L was determined. Therefore, the NOEC (no observed effect concentration) after 72 hours was determined to be 100 mg P 70/05/S-4/L.

Percent inhibition of yield:

Treatment group

 

% Inhibition of yield

 

mg P 70/05/S-4/L nominal

0-24h

0-48h

0-72h

Control (test medium)

0

0

0

100.0

2.8

0

0

During the exposure period of 72 hours, no inhibition of yield at the tested concentration of 100 mg P 70/05/S-4/L was determined. Therefore, the NOEC (no observed effect concentration) after 72 hours was determined to be 100 mg P 70/05/S-4/L.

Validity criteria fulfilled:
yes
Conclusions:
The toxicity of N-[3(5)-Methyl-1 H-pyrazol-1 -yl-methyl]acetamide to aquatic algae was determined according to OECD Guideline 201 (Alga, Growth Inhibition Test). Under laboratory conditions no inhibitory effects of the test item on average specific growth rate and yield were determined. The NOEC (no observed effect concentration) after 72 hours was determined to be 100 mg/L.
Executive summary:

The toxicity of N-[3(5)-Methyl-1 H-pyrazol-1 -yl-methyl]acetamide to aquatic algae was determined according to OECD Guideline 201 (Alga, Growth Inhibition Test). Under laboratory conditions no inhibitory effects of the test item on average specific growth rate and yield were determined. The NOEC (no observed effect concentration) after 72 hours was determined to be 100 mg/L.


Description of key information

The toxicity of N-[3(5)-Methyl-1 H-pyrazol-1 -yl-methyl]acetamide to aquatic algae was determined according to OECD Guideline 201 (Alga, Growth Inhibition Test). Under laboratory conditions no inhibitory effects of the test item on average specific growth rate and yield were determined. The NOEC (no observed effect concentration) after 72 hours was determined to be 100 mg/L.

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:
100 mg/L

Additional information

The NOEC (no observed effect concentration) after 72 hours was determined to be 100 mg/L.