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Ecotoxicological information

Toxicity to aquatic plants other than algae

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Reference
Endpoint:
toxicity to aquatic plants other than algae
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From September 30, 2016 to November 09, 2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 221 (Lemna sp. Growth Inhibition Test)
GLP compliance:
yes
Test organisms (species):
Lemna minor
Details on test organisms:
- Source (laboratory, culture collection): Canadian Phycological Culture Centre, Waterloo, ON, Canada
Test type:
static
Water media type:
freshwater
Total exposure duration:
7 d
Test temperature:
23-26°C
Nominal and measured concentrations:
Nominal concentrations: 26.0, 36.4, 51.0, 71.4 and 100 mg/L
Details on test conditions:
- Test vessel: 250 mL Erlenmeyer flask
- Test volume: ~125 mL
- Type of cover: sealed with foam plugs
- No. of fronds per replicate: 11
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6
- Photoperiod: Continuous 24-h light
- Light intensity and quality: 107-117μmol/m2/s
Reference substance (positive control):
yes
Remarks:
Nickel sulphate hexahydrate (CAS No. 10101-97-0)
Duration:
7 d
Dose descriptor:
EC50
Remarks:
for yield
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
frond number
Duration:
7 d
Dose descriptor:
EC50
Remarks:
for yield
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks:
dry weight
Duration:
7 d
Dose descriptor:
EC50
Remarks:
for Specific Growth Rate
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
frond number
Duration:
7 d
Dose descriptor:
EC50
Remarks:
for Specific Growth Rate
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks:
dry weight
Results with reference substance (positive control):
The 7-day EC25 for Nickel sulphate hexahydrate (CAS No. 10101-97-0) was 20.6 mg Ni/L.

The control doubling time was calculated to be 1.89 days. The initial pH measurements did not differ from the final measurements by more than 1.5 units and the test was maintain within24 ± 2°C. At the end of test, the plants in the negative control up to the 100 mg/L test concentration appeared light green, healthy, with some transparent fronds.

 

Table 1. Mean Yield and Specific Growth Rate (SGR) Based on Frond Number

Nominal Concentration (mg/L)

Frond Number (Day 0-7)

Mean Yield

SD

% CV

Mean SGR

SD

% CV

 Lab Control (0)

133.5

16.0

12.0

0.37

0.02

4.4

26.0

115.0

9.8

8.6

0.35

0.01

3.2

36.4

120.3

10.5

8.7

0.35

0.01

3.2

51.0

127.3

33.7

26.5

0.36

0.03

9.4

71.4

113.7

6.8

6.0

0.35

0.01

2.3

100.0

110.7

4.5

4.1

0.34

0.01

1.5

SD: Standard Deviation

% CV: Percent Coefficient of Variation

 

Table 2. Mean Yield and Specific Growth Rate (SGR) Based on Dry Weight

Nominal Concentration (mg/L)

Dry Weight (Day 0-7)

Mean Yield

(mg)

SD

(mg)

% CV

Mean SGR

SD

% CV

 Lab Control (0)

12.55

1.17

9.4

0.39

0.01

3.3

26.0

9.91

1.49

15.1

0.36

0.02

5.4

36.4

10.46

1.34

12.8

0.37

0.02

4.6

51.0

10.44

3.58

34.3

0.36

0.04

12.0

71.4

9.30

0.50

5.4

0.35

0.01

2.0

100.0

8.79

0.36

4.1

0.34

0.01

1.5

SD: Standard Deviation

% CV: Percent Coefficient of Variation

 

Table 3. Mean Percent Inhibition in Yield Based on Frond Number and Dry Weight

Nominal Concentration

(mg/L)

Mean % Inhibition

(Frond Number)

Mean % Inhibition

(Dry Weight)

Lab Control (0)

N/A

N/A

26.0

13.9

21.0

36.4

9.9

16.7

51.0

4.6

16.8

71.4

14.9

25.9

100.0

17.1

29.9

N/A: Not Applicable

 

Table 4. Mean Percent Inhibition in Specific Growth Rate (SGR) Based on Frond Number and Dry Weight

Nominal Concentration

(mg/L)

Mean % Inhibition

(Frond Number SGR)

Mean % Inhibition

(Dry Weight SGR)

Lab Control (0)

N/A

N/A

26.0

5.2

8.1

36.4

3.6

6.3

51.0

2.2

7.3

71.4

5.6

10.1

100.0

6.5

11.9

N/A: Not Applicable

 

Table 5. Test Endpoint Summary for CR SB32N2-Yield and SGR

 

Nominal Test Item Concentrations (mg/L)

EC50 (95% CL)

(mg/L)

NOEC

(mg/L)

LOEC

(mg/L)

Yield

Frond Number

>100 (N/A)

100

>100

Dry Weight

>100 (N/A)

71.4

100

SGR

Frond Number

>100 (N/A)

100

>100

Dry Weight

>100 (N/A)

71.4

100

Note: N/A-Not Applicable

Validity criteria fulfilled:
yes
Conclusions:
According to OECD 221 test method, the 7-days EC50 of CR SB32N2 was >100 mg/L.
Executive summary:

This test using the procedures outlined in the Maxxam Study Plan for TOX1615 which is based on the SOP for the OECD 221 (BBY2 SOP-00067) and OECD 221 (OECD, 2006). The results of this OECD 221 test for CR SB32N2 show that test validity criteria was met.

Based on the nominal concentrations of CR SB32N2:

1.     The 7-Day EC50 for yield based on frond number was >100 mg/L. The NOEC and LOEC was 100 mg/L and >100 mg/L, respectively.

2.     The 7-Day EC50 for yield based on dry weight was >100 mg/L. The NOEC and LOEC was 71.4 mg/L and 100 mg/L, respectively.

3.     The 7-Day EC50 for Specific Growth Rate based on frond number was >100 mg/L. The NOEC and LOEC was 100 mg/L and >100 mg/L, respectively.

4.     The 7-Day EC50 for Specific Growth Rate based on dry weight was >100 mg/L. The NOEC and LOEC was 71.4 mg/L and 100 mg/L, respectively.

Description of key information

The 7-days EC50 of CR SB32N2 was >100 mg/L for Lemna minor (OECD TG221).

Key value for chemical safety assessment

EC50 for freshwater plants:
100 mg/L

Additional information

The test was considered valid as the control doubling time was calculated to be 1.89 days which met the test validity criteria of ≤2.5days. The pH and the temperature of the test solutions were both within the ranges outlined in the OECD 221 test guideline. The measured concentrations of CR SB32N2 were within 80-120% of their nominal concentrations.

Based on the nominal concentrations of CR SB32N2:

1.   The 7-Day EC50 for yield based on frond number was >100 mg/L. The NOEC and LOEC was 100 mg/L and >100 mg/L, respectively.

2.   The 7-Day EC50 for yield based on dry weight was >100 mg/L. The NOEC and LOEC was 71.4 mg/L and 100 mg/L, respectively.

3.   The 7-Day EC50 for Specific Growth Rate based on frond number was >100 mg/L. The NOEC and LOEC was 100 mg/L and >100 mg/L, respectively.

4.   The 7-Day EC50 for Specific Growth Rate based on dry weight was >100 mg/L. The NOEC and LOEC was 71.4 mg/L and 100 mg/L, respectively.