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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
Study period:
Range finding test was conducted 2005-11-25 to 2005-12-02. Definitive test conducted 2005-12-07 to 2005-12-14. Final report signed off on 2006-02-08
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Meets the criteria for classification as reliable without restriction acording to Klimisch et al (1997)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2006
Report Date:
2006

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 221 (Lemna sp. Growth Inhibition Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
Test preparations were analysed on day 0 (fresh media) and on days 2, 5 and 7.

Test solutions

Details on test solutions:
Culture medium control and test concentrations of 1.0, 3.2, 10, 32 and 100 mg ai/l. Test concentrations were adjusted for the purity of the test material and test concentrations refer to active ingredient (ai).

Test organisms

Test organisms (species):
Lemna minor
Details on test organisms:
Source of test organisms: Blades Biological, Cowden, Edenbridge, Kent, United Kingdom.

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 6.7 to 6.8 and at the end of the test the range was from 7.0 to 7.6.

A general increase in pH between media renewal periods was observed. This effect was considered to be due to bicarbonate in the culture medium being used as a source of CO2 for respiration, which results in an increase in the pH of the culture.
Dissolved oxygen:
Not Applicable
Salinity:
Not Applicable
Nominal and measured concentrations:
Analysis of the freshly prepared test concentrations on Day 0 and the old or expired test concentrations on Days 2, 5 and 7 showed measured test concentrations to be near nominal and hence the results are based on nominal test concentrations only.
Details on test conditions:
Three flasks each containing 250 ml of solution were prepared for the control and each treatment group. The control group was maintained under identical conditions but not exposed to the test material. Each control and test flask was inoculated with 3 colonies of Lemna minor (total 9 fronds). The flasks were then incubated at 24 ± 2°C under constant illumination (intensity approximately 7000 lux) for 7 days. As the test material forms coloured test solutions, the test was conducted on a black, non-reflecting surface. On days 2 and 5 the test solutions were renewed. The number of fronds present in each test and control culture was recorded on days 0, 2, 5 and 7 along with observations on frond size, appearance, root length and number of colonies present.
Reference substance (positive control):
yes
Remarks:
Run as a separate study every six months to confirm test system responds as expected. For FSM-003B the positive control substance was 3,5-dichlorophenol and the test was conducted under the study number 39/768.

Results and discussion

Effect concentrationsopen allclose all
Duration:
7 d
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
frond number
Remarks:
Average specific growth rate
Duration:
7 d
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
frond number
Remarks:
Yield
Duration:
7 d
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
other: dry weight for average specific growth rate
Duration:
7 d
Dose descriptor:
EC50
Effect conc.:
59 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
other: dry weight for yield
Duration:
7 d
Dose descriptor:
NOEC
Effect conc.:
3.2 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
frond number
Remarks:
Average specific growth rate
Duration:
7 d
Dose descriptor:
NOEC
Effect conc.:
3.2 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
frond number
Remarks:
Yield
Duration:
7 d
Dose descriptor:
NOEC
Effect conc.:
3.2 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
other: dry weight for average specific growth rate
Duration:
7 d
Dose descriptor:
NOEC
Effect conc.:
3.2 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
other: dry weight for yield
Results with reference substance (positive control):
The positive control reponded as expected demonstrating that the test system was responding normally.
Reported statistics and error estimates:
Statistical analysis of the average specific growth rate data was carried out for the control and all test concentrations using one way analysis of variance incorporating Bartlett's test for homogeneity of variance (Sokal and Rohlf 1981) and Dunnett's multiple comparison procedure for comparing several treatments with a control (Dunnett 1955). There were no statistically significant differences between the control, 1.0 and 3.2 mg/l test concentrations (P~0.05), however all other test concentrations were significantly different (P<0.05) and, therefore the "No Observed Effect Concentration" (NOEC) in terms of inhibition of average specific growth rates calculated from dry weight was 3.2 mg/l.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The average specific growth rate EC50 for frond number, dry weight was > 100 mg/l and on this basis the test substance is considered to be non-toxic to duckweed (Lemna minor sp.)
Executive summary:

Introduction

The study was performed to assess the effect of the test substance on the growth of the freshwater plant Lemna minor. The method was designed to be compatibile with the following guideline:

Draft OECD Guideline 'Lemna Growth Inhibition Test' (April 2004)

Results & Conclusion

The 7 day average specific growth rate ErC50 based on the frond number was >100mg ai/l and based on the dry weight was >100 mg ai/l. The 7 day yield ErC50 based on the frond number was >100mg ai/l and based on the dry weight was 59 mg ai/l. Therefore it is concluded that the test substance is non-toxic to duckweed (Lemna minor sp.).