Registration Dossier

Ecotoxicological information

Toxicity to aquatic plants other than algae

Administrative data

Endpoint:
toxicity to aquatic plants other than algae
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Meets the criteria for classification as reliable without restriction according to Klimisch et al (1997)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2009

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 221 (Lemna sp. Growth Inhibition Test)
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
S191820 concentration measured at 0 and 7 days

Test solutions

Vehicle:
no
Details on test solutions:
Culture medium control and nominal concentrations 0f 5.0, 11, 25, 55 and 120 mg/l

Test organisms

Test organisms (species):
Lemna minor
Details on test organisms:
The test organism was the duckweed Lemna minor Strain ST from laboratory cultures maintained under axenic conditions. The cultures were originally obtained from the Botanical Institute of the University of Jena, Germany.

Study design

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
7 d

Test conditions

Hardness:
Not Applicable
Test temperature:
24 degrees centigrade +/- 2 degrees
pH:
At the start of the test the pH ranged from 5.6 to 5.7 and at the end of the test the range was from 6.2 to 6.3.
Dissolved oxygen:
Not Applicable
Salinity:
Not Applicable
Nominal and measured concentrations:
Test concentrations were culture medium control and S191820 at nominal concnetrations of 5.0, 11, 25, 55 and 120 mg/l. The mean measured concentrations ranged from90 to 100% of the nominal values.
Details on test conditions:
The test vessels were borosilicate glass cylindrical dishes of 300 ml nominal capacity with loose-fitting lids. Each vessel contained 160 ml of test solution. The cultures were incubated at 24 ± 2C (the nominal test temperature), under continuous illumination, of approximately 8200 lux, using "warm-white" lights in an incubator.
Reference substance (positive control):
not required

Results and discussion

Effect concentrationsopen allclose all
Duration:
7 d
Dose descriptor:
NOEC
Effect conc.:
25 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
frond number
Duration:
7 d
Dose descriptor:
LOEC
Effect conc.:
55 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
frond number
Duration:
7 d
Dose descriptor:
EC50
Effect conc.:
> 120 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
frond number
Duration:
7 d
Dose descriptor:
NOEC
Effect conc.:
25 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: Specific growth rate (frond number)
Duration:
7 d
Dose descriptor:
LOEC
Effect conc.:
55 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: Specific growth rate (frond number)
Duration:
7 d
Dose descriptor:
EC50
Effect conc.:
> 120 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: Specific growth rate (frond number)
Duration:
7 d
Dose descriptor:
NOEC
Effect conc.:
25 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: Dry weight
Duration:
7 d
Dose descriptor:
LOEC
Effect conc.:
55 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: Dry weight
Duration:
7 d
Dose descriptor:
EC50
Effect conc.:
> 120 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: Dry weight
Duration:
7 d
Dose descriptor:
NOEC
Effect conc.:
25 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: Specific growth rate (dry weight)
Duration:
7 d
Dose descriptor:
LOEC
Effect conc.:
55 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: Specific growth rate (dry weight)
Duration:
7 d
Dose descriptor:
EC50
Effect conc.:
> 120 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: Specific growth rate (dry weight)
Details on results:
Individual results as follows:

Based on the increase in number of fronds the results obtained were:
No observed effect (P=0.05) concentrations (NOEC) = 25 mg l-1
Lowest observed effect (P=0.05) concentration (LOEC) = 55 mg l-1
Median effective concentration, EyC50 (frond number) >120 mg l-1

Based on average specific growth rate (frond number) the results obtained were:
No observed effect (P=0.05) concentrations (NOEC) = 25 mg l-1
Lowest observed effect (P=0.05) concentration (LOEC) = 55 mg l-1
Median effective concentration, ErC50 (frond number) >120 mg l-1

Based on the increase in dry weight of the plants over the test period, the results obtained were:
No observed effect (P=0.05) concentration (NOEC) = 25 mg l-1
Lowest observed effect (P=0.05) concentration (LOEC) = 55 mg l-1
Median effective concentration, EyC50 (dry weight) >120 mg l-1

Based on average specific growth rate (dry weight) the results obtained were:
No observed effect (P=0.05) concentrations (NOEC) = 25 mg l-1
Lowest observed effect (P=0.05) concentration (LOEC) = 55 mg l-1
Median effective concentration, ErC50 (dry weight) >120 mg l-1
Reported statistics and error estimates:
The number of fronds and numbers of plants in each test vessel was measured on days 2,5 and 7.

The data for increase in frond number, growth rate and dry weight were examined by one-way analysis of variance, and a multiple comparison procedure (Dunnett’s t-test) was used to identify significant differences (P=0.05, two tailed) from the culture medium control.

No attempt was made to analyse the data for plant numbers, since frond numbers and weight increases were considered more reliable estimates of Lemna growth.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
S191820 is considered to be non-toxic to duckweed (lemna minor sp.)
Executive summary:

S191820 is considered to be non-toxic to duckweed (Lemna minor sp.)