Registration Dossier

Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Currently viewing:

Administrative data

Link to relevant study record(s)

Reference
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
10 Jan - 16 Mar 2017
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)
Version / remarks:
2006
Deviations:
yes
Remarks:
The concentration of NaHCO3 was increased to be twice of that indicated in the Guideline 201. This cocnentration has been found to be optimal.
GLP compliance:
yes (incl. certificate)
Remarks:
Hessisches Ministerium für Umwelt, Energie, Landwirtschaft und Verbraucherschutz, Wiesbaden, Germany
Analytical monitoring:
yes
Details on sampling:
- Concentrations: control and all test item concentrations
- Sampling method: samples were taken at test start and test end
- Sample storage conditions before analysis: samples were stored at 2 to 8 °C until they were analysed.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Differential loading:
Separate solutions were made for each test concentration in ultrapure water. Aliquots of these solutions were made up with ,,intermediate dilution" and algal inoculum (or diluted ,,intermediate dilution") to give 50 mL of final volume.Suspensions of the test item were individually prepared for each test concentration in ultrapure water and shaken on a shaking machine at approx 130 rpm for 24 hrs at RT and filtrating through glass fibre filter. The eluates were used without further dilution steps (detailed information are summarized within the section "Any other information on material and methods")
- Controls: yes
- Others: As reagents' blank without algal inoculation three test solutions were prepared as described above containing a 1:10 diluted intermediate dilution of the mineral nutrients stock solution instead of the algal pre-culture.

Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Common name: Green algae
- Strain: 86.81
- Source: Sammlung von Algenkulturen, Pflanzenphysiologisches lnstitut der Universität Göttingen
- Age of inoculum (at test initiation): 72 h (pre-culture)

ACCLIMATION
- Acclimation period: 3 d
- Culturing media and conditions: same
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Test temperature:
24 - 26 °C
pH:
8.12 - 9.18 (Control)
8.09 - 9.36 (Test item concentration)
Nominal and measured concentrations:
Control, 11.1, 22.2, 44.4, 88.9 and 177.8 mg test item/L (nominal)
Control, 10, 20, 40, 80 and 160 mg active ingredient/L (nominal)
Details on test conditions:
TEST SYSTEM
Test vessel:
- Type: open
- Material, size, headspace, fill volume: 50 mL glass cylinders, 50 mL volume;
- Initial cells density: 3 x 1000
- Control end cells density: 3.3 x 100000
- No. of vessels per concentration (replicates): 7
- No. of vessels per control (replicates): 7

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: ultra pure water
- Intervals of water quality measurement: test start and test end

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Photoperiod: constant illumination
- Light intensity and quality: ≥120 µE/m²s (ca 8000 lux)

EFFECT PARAMETERS MEASURED:
- Determination of cell concentrations: photometrical measurement (spectrophotometer at 578 nm); cell numbers were calculated using a calibration curve of cell numbers versus extinction values (578 nm)
- Chlorophyll measurement:

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2.0
Reference substance (positive control):
no
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EL10
Effect conc.:
95.43 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOELR
Effect conc.:
44.4 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EL10
Effect conc.:
85.86 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOELR
Effect conc.:
40 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Details on results:
- Exponential growth in the control (for algal test): yes
- Observation of abnormalities: no

Reported statistics and error estimates:
Estimation of the inhibition values for yield and the growth rates of the algae as well as the statistical calculations were conducted according to the Guideline using the commercial computer program ToxRatPro Version 3.2.1.

Results of Analytics:

Formula of the active Substance: C24H54N204P2S2Zn

According to this formula the contents of the different elements in the molecule are distributed as C: 46.04%; H: 8.69%; N: 4.7%; O: 10.22 %; P: 9.89%; S: 10.24 %; Zn: 10.44%

Amount of P, S and Zn in the treatments measured:

 

Time

Concentration of the Test Item, active Substance [mg/L]

mg/L

P

S

Zn

t0

Control

0.486

2.128

0.006

t0

10.01

0.599

2.421

0.084

t0

19.94

0.720

2.651

0.205

t0

40.00

0.981

3.196

0.265

t0

79.99

1.481

4.315

0.299

t0

159.98

3.301

8.120

0.438

t72h

Control

0.410

2.040

0.004

t72h

10.01

0.584

2.498

0.102

t72h

19.94

0.740

2.929

0.224

t72h

t72h

t72h

40.00

79.99

159.98

1.044

1.771

3.270

3.325

4.880

8.100

0.298

0.298

0.445

Accordingly, the following concentrations of active substance are calculated:

 

Time

nom. conc. of active substance [mg/L]

Measured conc. of active substance

Basis P

Basis S

Basis Zn

mg Test ltem/L

mg Test ltem/L

mg Test ltem/L

t0

Control

0.000

0.000

0.000

t0

t0

10.01

19.94

1.143

2.366

2.861

5.107

0.747

1.906

t0

40.00

5.005

10.430

2.481

t0

79.99

10.061

21.357

2.807

t0

159.98

28.463

58.516

4.138

t72h

t72h

t72h

t72h

t72h

t72h

Control

10.01

19.94

40.00

79.99

159.98

0.000

1.759

3.337

6.411

13.761

28.918

0.000

4.473

8.682

12.549

27.734

59.180

0.000

0.939

2.107

2.816

2.816

4.224

Accordingly, the following recovery rates are calculated:

 

Time

nom. conc. of active substance [mg/L]

Basis P

mg Test ltem/L

% Nominal Conc.

Recovery% of t0

t0

Control

0

-

-

t0

t0

10.01

1.143

11.4

-

t0

19.94

2.366

11.9

-

t0

40.00

5.005

12.5

-

t0

79.99

10.061

12.6

-

t0

159.98

28.463

17.8

-

t72h

Control

0

-

-

t72h

10.01

1.759

17.6

154.0

t72h

19.94

3.337

16.7

141.0

t72h

40.00

6.411

16.0

128.1

t72h

79.99

13.761

17.2

136.8

t72h

159.98

28.918

18.1

101.6

Time

nom. conc. of active substance [mg/L]

Basis S

mg Test ltem/L

% Nominal Conc.

Recovery % of t0

t0

t0

t0

t0

t0

t0

Control

10.01

19.94

40.00

79.99

159.98

0

2.861

5.107

10.430

21.357

58.516

-

28.6

25.6

26.1

26.7

36.6

-

-

-

-

-

-

t72h

t72h

t72h

t72h

t72h

t72h

Control

10.01

19.94

40.00

79.99

159.98

0

4.473

8.682

12.549

27.734

59.180

-

44.7

43.5

31.4

34.7

37.0

-

156.3

170.0

120.3

129.9

101.1

 

 

Time

nom. Conc. of active substance [mg/L]

Basis Zn

Mean

Recoveries,

% of t 0, total [Basis P, 5, Zn]

 

mg Test ltem/L

 

% Nominal Conc.

 

Recovery % of t0

t0

t0

t0

t0

t0

t0

Control

10.01

19.94

40.00

79.99

159.98

0

0.747

1.906

2.481

2.807

4.138

-

7.5

9.6

6.2

3.5

2.6

-

-

-

-

-

-

-

-

-

-

-

-

t72h

t72h

t72h

t72h

t72h

t72h

Control

10.01

19.94

40.00

79.99

159.98

0

0.939

2.107

2.816

2.816

4.224

-

9.4

10.6

7.0

3.5

2.6

-

125.6

110.6

113.5

100.3

102.1

-

145.3

140.5

120.6

122.3

101.6

Table 1: Validity criteria for OECD 201

Criterion from the guideline

Outcome

Validity criterion fulfilled

The biomass in the control cultures should have increased exponentially by a factor of at least 16 within the 72-hour test period.

123.2

Yes

The mean coefficient of variation for section-by-section specific growth rates (days 0-1, 1-2 and 2-3, for 72-hour tests) in the control cultures must not exceed 35%

16.4%

Yes

The coefficient of variation of average specific growth rates during the whole test period in replicate control cultures must not exceed 7% in tests with Pseudokirchneriella subcapitata and Desmodesmus subspicatus. For other less frequently tested species, the value should not exceed 10%.

3.0%

Yes

Validity criteria fulfilled:
yes

Description of key information

ErL50 (72h) >100 mg test item/L (Desmodesmus subspicatus, nominal, OECD 201, growth rate, key study)

ErL50 (72h) > 100 mg a.i./L (Desmodesmus subspicatus, nominal, OECD 201, growth rate, key study)

ErL10 (72 h) 95.43 mg test item/L (Desmodesmus subspicatus, nominal, OECD 201, growth rate, key study)

ErL10 (72 h) 85.86 mg a.i./L (Desmodesmus subspicatus, nominal, OECD 201, growth rate, key study)

Key value for chemical safety assessment

Additional information

One experimental study is available investigating the toxicity of the test item to the freshwater green algae Desmodesmus subspicatus (Lebertz, 2017c). The study was performed according to OECD 201 and GLP with analytical monitoring of the test item concentration during the exposure period of 72 hours. The test was performed using five concentrations of "WAFs" (Water accommodated fractions) in the nominal range of 11.1 to 178.6 mg/L of the test item representing 10 to 160 mg/L of active matter (90% of the test item are representing the active matter). Suspensions of the test item were individually prepared for each test concentration in ultrapure water and shaken on a shaking machine at approximately 130 rpm for 24 h at room temperature. After the shaking procedure the suspensions were filtered through glass fibre filters. The eluates (WAFs) were used directly without any further dilution step. As a result of the supporting analyse it can be stated that minor concentrations of the test item were measured due to WAF-preparation. Nevertheless the measured concentrations remained stable during incubation and thus, the results of the biological part should be based on the nominal concentrations applied because the necessary stability of 80% could be shown. The EL50 (72h) for growth rate was determined to be > 100 mg/L based on the active ingredient as well as on the test item. The EL10 (72h) for growth rate was determined to be at 95.43 mg test item/L and based on the active ingredient it was determined to be at 85.86 mg a.i./L. The validity criteria for the study as given by the OECD Guideline 201 were all met and the study is therefore considered to be valid.