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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:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
GLP compliance:
no
Analytical monitoring:
no
Vehicle:
no
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Test temperature:
20 °C
Nominal and measured concentrations:
Nominal: Control, 0.16, 0.31, 0.63, 1.25, 2.50, 5.0, 10.0, 20.0 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: Erlenmeyer flasks
- Size, fill volume: 250 mL, 100 mL
- Initial cells density: 10,000 cells/mL
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): no data

GROWTH MEDIUM
- Standard medium used: yes, OECD medium

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: fluorimeter measurements

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2
Reference substance (positive control):
no
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
5.1 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC20
Effect conc.:
1.57 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass

Table 1: Fluorimeter measurements at test start and after 72 h of exposure

Concentration (mg/L)

Fluorimeter measurement

(% of control)

0 h

72 h

Control

-

-

0.16

94.74

109.02

0.31

101.75

94.00

0.63

91.23

87.95

1.25

105.26

82.16

2.5

101.75

73.77

5.0

94.74

50.36

10.0

101.75

32.48

20.0

105.26

29.37

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
21 Jul - 24 Jul 2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Version / remarks:
adopted in 2006
Deviations:
yes
Remarks:
Higher test temperature (guideline: max. 24 °C; test: max. 29 °C)
Qualifier:
according to
Guideline:
EU Method C.3 (Algal Inhibition test)
Version / remarks:
adopted in 2008
Deviations:
yes
Remarks:
Use of 64 mg FeCL3*6H2O/L instead of 80 mg/L.
GLP compliance:
yes (incl. certificate)
Remarks:
Landesamt für Umwelt, Wasserwirtschaft und Gewerbeaufsicht, Mainz, Germany
Analytical monitoring:
yes
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A stock solution containing 10 g/L was prepared using the following procedure: 10 g test item was mixed with 1.1 g NaOH (45%). 40 mL deionised water (80 – 100 °C) was added. After homogenisation with a glass stirrer, 85 mL deionised water (room temperature) was added. Then, the vessel was stirred on a magnetic stirrer. 0.5 M NaOH was added until the resulting solution was clear. The pH of the solution was adjusted to 7.8 ± 0.2 with 1 M HCl. the solution was transferred into a volumetric flask and filled up to 1000 mL with deionised water. From this stock solution, the concentrations to be tested were prepared by diluting with deionised water.
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Strain: Chodat
- Source (laboratory, culture collection): The culture of Desmodesmus subspicatus was obtained in June 2010 by MBM Science Bridge GmbH (Institut für Pflanzenphysiologie, Universität Göttingen).
- Age of inoculum (at test initiation): 5 days
- Method of cultivation: The algae are kept as stock culture on solid agar at 8 °C. From an aliquot of this stock culture, the pre-culture was prepared.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Test temperature:
26 - 29 °C
pH:
7.6 - 8.8
Nominal and measured concentrations:
Nominal: 0, 0.22, 0.46, 1.0, 2.2, 4.6, 10, 22, 46 mg/L
Measured (initial): < LOD, 0.37, 0.42, 0.53, 0.91, 2.01, 4.35, 11.32, 24.55 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: Round cuvettes of 10 mm diameter
- Aeration: None, magnetic stirring
- Initial cells density: 2.2E04 cells/mL
- Control end cells density: 180E04 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Deionised water
- Intervals of water quality measurement: Temperature was measured every 24 h, pH was measured at test start and test end.

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Light intensity and quality: 5900 - 6100 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: Cell numbers were determined by photometric measurement

TEST CONCENTRATIONS
- Spacing factor for test concentrations: approx. 2.1
- Range finding study
- Test concentrations: 0.08, 0.125, 0.2, 0.32, 0.5, 0.8, 1.25, 2.0, 3.2 mg/L
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
6.3 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% CL = 5.1 - 8.7 mg/L
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.91 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
2.3 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks on result:
other: 95% CL = 2.0 - 2.6 mg/L
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.53 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
2.7 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
other: yield
Remarks on result:
other: 95% Cl = 2.3 - 3.2 mg/L
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.91 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
other: yield
Details on results:
- Exponential growth in the control (for algal test): yes, increase factor of 82
- All validity criteria of the guideline are fulfilled.
- Microscopical observations: Normal growth up to 10 mg/L, no cells in the 22 and 46 mg/L treatments
- Observation of abnormalities (for algal test): Treatments 22 and 46 mg/L showed clouded test solution
- Analytical measurements: The recovery rates at test start ranged between 44 and 170%. After 72 h, only in the two highest treatments 2 - 20% of nominal values could be detected. Therefore the measured start concentration was used for the determination of the results.

Inhibition

Nom. Conc. in mg/L

Measured Conc. in mg/L

% Inhibition

Growth Rate µ

Area under the Curve AUC

Yield

0

0

0

0

0

0.22

0.37

-0.14

-0.72

-0.62

0.46

0.42

-0.63

-0.72

-2.83

1.0

0.53

0.20

2.98

0.90

2.2

0.91

0.74

10.61

3.24

4.6

2.0

10.93

45.19

38.25

10

4.4

32.35

79.09

76.71

22*

11.3

39.51

62.70

83.46

46*

24.6

25.04

-10.00

67.61

*Treatments 22 and 46 mg/L showed clouded test solution, photometric measurement not evaluable.

 

Measured Concentrations in mg/L and corresponding Recovery Rates in %

Nom. Conc. in mg/L

Measured Conc. 0h in

mg/L

% Nom. Conc.

Measured Conc. 72 h in mg/L

& Nom. Conc.

% Recovery

0

--

--

--

--

--

0.22

0.37

170

--

--

--

0.46

0.42

91

--

--

--

1

0.53

53

--

--

--

2.2

0.91

42

--

--

--

4.6

2.01

44

--

--

--

10

4.35

44

--

--

--

22

11.32

51

0.35

2

3

46

24.55

53

9

20

37

 

Description of key information

ErC50 (72h) > 4.4 mg/L; NOErC = 0.91 mg/L for Desmodesmus subspicatus (OECD 201)

Key value for chemical safety assessment

Additional information

Two studies investigating the toxicity to aquatic algae of N-methyl-N-(C18-(unsaturated)alkanoyl)glycine (EC 701-177-3) are available.

The key study was carried out according to OECD guideline 201 under GLP conditions including analytical measurement. In this static test, Desmodesmus subspicatus was exposed to eight test concentrations (0.22, 0.46, 1.0, 2.2, 4.6, 10, 22 and 46 mg/L). Analytical measurements verified the test item concentration to be 44 – 170% of the nominal test concentration at test start for all eight concentrations. The effect concentrations were based on the initial test concentrations. Only for the two highest test concentrations analytical measurements were done after 72h. In these two highest test concentrations (nominal: 22 and 46 mg/L) a recovery of 3 and 37% respectively was determined. But as turbidity was observed for these both highest test concentrations, they were not evaluated as reliable as photometric measurement was not evaluable. In addition, it could not be excluded that these are physical effects due to the undissolved test material. In the study report an EC 50 of 6.3 mg/L for growth rate was reported although the inhibition is below 50% for the highest reliable test concentration (32.35% for 10 mg/L nominal = 4.4 mg/L measured). Thus, an EC50 > 4.4 mg/L for growth rate is stated. The NOEC is reported as 0.91 mg/L (measured).

The supporting study was carried out under non-GLP conditions similar to OECD guideline 201 and without analytical measurement. Desmodesmus subspicatus was exposed to eight test concentrations (0.16, 0.31, 0.63, 1.25, 2.50, 5.0, 10.0, 20.0 mg/L) under static conditions. An EbC20 (72h) of 1.57 mg/L and an EbC50 (72h) of 5.1 mg/L was determined based on biomass.