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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:
2006
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 221 (Lemna sp. Growth Inhibition Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
Name: FAT 40045/Z TE
Batch number: AT-2486840
EAS Test item code: 2014-000185
Appearance / colour: solid / dark blue
Purity nominal: >90 %w/w
Molecular weight: 1191.02 g/mol (base)
Date of analysis: 04 Oct 2013
Expiry date: 03 Jul 2018
Storage conditions: cool (+1 to +10 °C), dark, dry
Analytical monitoring:
yes
Details on sampling:
The test medium samples (100 mL) were stored deep-frozen (below -18 °C) until analysis
Vehicle:
not specified
Details on test solutions:
The necessary amount of test item for preparing the stock solution S1 was weighed and transferred to a volumetric flask. Test medium was added up to the bench mark and the solution was homogenised by shaking. Lower concentrations of the test item were prepared by dilution of the stock solution.
Test organisms (species):
Lemna gibba
Details on test organisms:
The test organism was the aquatic plant duckweed, Lemna gibba G3 (Alismatales: Araceae). The plants used in this study were taken as aseptic clones from the cultivation of the testing facility. They were primarily cultured by Dr. Janet Slovin, Horticulture Crops Quality Laboratory, U.S. Department of Agriculture. BARC-West, Bldg. 050 HH-4, Beltsville, MD 20705, U.S.A. The plants were cultured in appropriate glass beakers under continuous illumination with OSRAM light tubes (L30/32-930 and L30/W72-965), at 6500 - 7000 lux. The temperature was 24 ± 2 °C. Before the test was started, plants were cultured under the same illumination and temperature conditions as those to be used for the toxicity test. Young, light-green plants of similar size and comprising 2 - 5 fronds were transferred onto fresh medium and cultured for 3 weeks prior to testing, with two further transfers onto fresh medium before initiating the test.
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
7 d
Test temperature:
22.9 – 24.8 °C
pH:
7.37 – 8.85
Nominal and measured concentrations:
Nominal concentrations: 0 (control), 0.298, 0.954, 3.05, 9.77, 31.3 and 100 mg/L
Details on test conditions:
Test procedure: semi-static test
Duration: 7 days
Temperature: 22.9 – 24.8 °C
pH-value of fresh solution: 7.37 – 8.85
Light intensity (mean): ~ 7000 lux
Light tubes: OSRAM light tubes (L 30 W77 and L 30 W25)
Exposure to light: continuously
Test vessels: 250 mL glass beakers filled with 150 - 200 mL
Number of fronds: 12 per test vessel
Reference substance (positive control):
no
Duration:
7 d
Dose descriptor:
EC10
Effect conc.:
17.4 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
frond number
Remarks:
Growth rate
Duration:
7 d
Dose descriptor:
EC20
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
frond number
Remarks:
Growth rate
Duration:
7 d
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
frond number
Remarks:
Growth rate
Duration:
7 d
Dose descriptor:
LOEC
Effect conc.:
0.298 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
frond number
Remarks:
Growth rate
Reported statistics and error estimates:
The statistical evaluation for day 7 was performed for yield of frond numbers, growth rate of frond numbers, growth rate dry weight and yield of dry weight. A test for normality of the data was performed by calculating the Shapiro-Wilk’s statistic, a test for homogeneity of the data was performed according to Levene.
The NOEC and LOEC were determined by using multiple comparison methods (Dunnett`s t-test; Williams test, descending order). As the percentage of inhibition was below 50 % for all parameters, only EC10- and EC20-values for yield of frond number, growth rate of frond number, yield of dry weight and growth rate of dry weight were determined by probit analysis following Gompertz procedure. The evaluation of data was performed by SAS® (2002- 2010).

Significant inhibitory effects were determined for all parameters at all test item concentrations (0.298 to 100 mg/L nominal). The overall LOEC was therefore determined to be 0.298 mg/L, the corresponding NOEC could not be observed and is supposed to be below 0.298 mg/L.

The nominal EC10-value was determined to be 0.0252 mg/L for yield of dry weight, 32.3 mg/L for growth rate of dry weight, 0.189 mg/L for yield of frond numbers and 17.4 mg/L for growth rate of frond numbers.

The nominal EC20-value was determined to be >100 mg/L for growth rate of frond numbers and dry weight, 3.03 mg/L for yield of frond numbers and 1.11 mg/L for yield of dry weight.

The nominal EC50-value for yield of dry weight, growth rate of dry weight, yield of frond numbers and growth rate of frond numbers was determined to be >100 mg/L.

The test is valid as the doubling time of control frond numbers was calculated to be 33.2 h, corresponding to 1.385 days at day 7. This is less than the maximum allowable doubling time set in OECD guideline 221 (60 h, 2.5 days).

Validity criteria fulfilled:
yes
Conclusions:
The nominal EC10-value was determined to be 0.0252 mg/L for yield of dry weight, 32.3 mg/L for growth rate of dry weight, 0.189 mg/L for yield of frond numbers and 17.4 mg/L for growth rate of frond numbers.
The nominal EC50-value for yield of dry weight, growth rate of dry weight, yield of frond numbers and growth rate of frond numbers was determined to be >100 mg/L.
Executive summary:

The aim of the study was to assess the effect of the test item FAT 40045/Z TE on the growth of Lemna gibba according to OECD Guideline 221 and derive EC10, 20, 50 and NOEC/LOEC values.

Test species was Lemna gibba G3 (Duckweed), nominal concentration of 0 (control), 0.298, 0.954, 3.05, 9.77, 31.3 and 100 mg/L was performed.

Vegetative growth was observed for a test period of 7 days by measuring the increase of frond numbers and dry weight. The following endpoints (NOEC/LOEC, EC10, 20, 50) were determined:

- frond numbers and dry weight

- growth rates of frond numbers and dry weight

- yield of frond numbers and dry weight

- doubling times of frond numbers

The initial mean measured concentration of FAT 40045/Z TE in the test item solutions was 111 % of nominal. The overall mean concentration of fresh and aged samples was 112 % of nominal. Toxicological endpoints were evaluated using nominal concentrations of the test item.

Significant inhibitory effects were determined for all parameters at all test item concentrations (0.298 to 100 mg/L nominal).

The overall LOEC was therefore determined to be 0.298 mg/L, the corresponding NOEC could not be observed and is supposed to be below 0.298 mg/L.

The nominal EC10-value was determined to be 0.0252 mg/L for yield of dry weight, 32.3 mg/L for growth rate of dry weight, 0.189 mg/L for yield of frond numbers and 17.4 mg/L for growth rate of frond numbers.

The nominal EC20-value was determined to be >100 mg/L for growth rate of frond numbers and dry weight, 3.03 mg/L for yield of frond numbers and 1.11 mg/L for yield of dry weight.

The nominal EC50-value for yield of dry weight, growth rate of dry weight, yield of frond numbers and growth rate of frond numbers was determined to be >100 mg/L.

The test is valid as the doubling time of control frond numbers was calculated to be 33.2 h, corresponding to 1.385 days at day 7. This is less than the maximum allowable doubling time set in OECD guideline 221 (60 h, 2.5 days).

Description of key information

The effect of the test item on the growth of Lemna gibba was assessed according to OECD Guideline 221.Significant inhibitory effects were determined for all parameters at all test item concentrations (0.298 to 100 mg/L nominal). The overall LOEC was therefore determined to be 0.298 mg/L, the corresponding NOEC could not be observed and is supposed to be below 0.298 mg/L.The nominal EC10-value was determined to be 0.0252 mg/L for yield of dry weight, 32.3 mg/L for growth rate of dry weight, 0.189 mg/L for yield of frond numbers and 17.4 mg/L for growth rate of frond numbers.The EC50-value for yield of dry weight, growth rate of dry weight, yield of frond numbers and growth rate of frond numbers was determined to be >100 mg/L.

Key value for chemical safety assessment

EC50 for freshwater plants:
100 mg/L
EC10 or NOEC for freshwater plants:
17.4 mg/L

Additional information