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Toxicity to terrestrial plants

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Reference
Endpoint:
toxicity to terrestrial plants: short-term
Type of information:
experimental study
Adequacy of study:
key study
Study period:
25 January 2015 to 23 June 2015
Reliability:
1 (reliable without restriction)
Qualifier:
according to
Guideline:
EPA OPPTS 850.4200 (Seed Germination/Root Elongation Toxicity Test)
Deviations:
no
GLP compliance:
yes
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- lot/batch No.of test material: E00031-700
- Expiration date of the lot/batch: 1 October 2015
- Purity: 98%

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Room temperature under nitrogen in the dark
- Stability under test conditions: Stable in container after opening, stable in water, light and soil.
- Solubility and stability of the test substance in the solvent/vehicle: Solubility in organic solvent = 1155 g/kg
Analytical monitoring:
yes
Remarks:
HPLC
Details on sampling:
The test substance was stored at room temperature, under nitrogen in the dark.
A stock solution of 1000 mg/L was prepared by dissolving 1020 mg of test substance (purity 98%) in tetrahydrofuran (THF). Test concentrations of: 5 mg/L, 10 mg/L, 50 mg/L, 100 mg/L, 50 mg/L and 1000 mg/L were obtained by diluting volumes of the stock solution in THF. 6 test groups of the test substance, a blank control and a cosolvent control were conducted with one replicate with 15 seeds.
Before the test, a saturated content of quatz sand was measured and mixed with the test solutions and THF. They were then placed in a ventilation cabinet to evaporate the cosolvent overnight. When the THF had evaporated completely, the quatz sand was divided and mixed with test water before being transferred to the petri dish. The seeds were positioned on the substrate allowing the adequate room for anticipated growth. The petri dishes were then sealed with PE cling film and placed in the artificial climate incubator, at a slight angle to facilitate linear growth. The test ended when at least 65% of the control seed had germinated and at least 20 mm long roots had grown.
Vehicle:
yes
Details on preparation and application of test substrate:
A stock solution of 1000 mg/L was prepared by dissolving 1020 mg of test substance (purity 98%) in tetrahydrofuran (THF). Test concentrations of: 5 mg/L, 10 mg/L, 50 mg/L, 100 mg/L, 50 mg/L and 1000 mg/L were obtained by diluting volumes of the stock solution in THF. 6 test groups of the test substance, a blank control and a cosolvent control were conducted with one replicate with 15 seeds.
Before the test, a saturated content of quatz sand was measured and mixed with the test solutions and THF. They were then placed in a ventilation cabinet to evaporate the cosolvent overnight. When the THF had evaporated completely, the quatz sand was divided and mixed with test water before being transferred to the petri dish. The seeds were positioned on the substrate allowing the adequate room for anticipated growth. The petri dishes were then sealed with PE cling film and placed in the artificial climate incubator, at a slight angle to facilitate linear growth. The test ended when at least 65% of the control seed had germinated and at least 20 mm long roots had grown.
Species:
Zea mays
Species:
Oryza sativa
Species:
other: Brassica juncea
Species:
Daucus carota
Species:
other: Citullus lanatus
Species:
Brassica oleracea var. capitata
Species:
other: Vinga radiata
Species:
Lactuca sativa
Species:
Cucumis sativus
Species:
Lycopersicon esculentum
Test type:
seed germination/root elongation toxicity test
Study type:
laboratory study
Substrate type:
filter paper
Limit test:
no
Total exposure duration:
9 d
Justification for exposure duration:
The study is complete when at least 65% of the control seeds have germinated (root length 5 mm or more) and have developed roots that are at least 20 mm long.
Test temperature:
24.1 - 25.6 degrees Celsius
pH:
5.0 - 6.58
Details on test conditions:
TEST SYSTEM
- Testing facility:
- Test container (type, material, size):
- Amount of soil:
- Method of seeding:
- No. of seeds per container: 15
- No. of plants: 10
- No. of replicates per treatment group: 2
- No. of replicates per control: 2
- No. of replicates per vehicle control: 2

GROWTH CONDITIONS
- Photoperiod: darkness
- Light source: none
- Light intensity and quality: none
- Day/night temperatures: 25 +/- 1 degrees Celsius

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Germination inhibition rate

VEHICLE CONTROL PERFORMED: yes
Reference substance (positive control):
no
Key result
Species:
other: Lycopersicon esculentum, Cucumis sativus, Lactuca sativa, Vigna radiata, Brassica oleracea, Citrullus lanatus, Daucus carota, Brassica juncea, Oryza sativa, Zea mays
Duration:
7 d
Dose descriptor:
EC50
Effect conc.:
> 1 000 other: mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
germination
Details on results:
SEED GERMINATION
- Percent seed germination: 66.7% - 100%

A volume for each test concentration of the prepared test stock solution, with a concentration of 1000 mg/L test substance, was mixed with quartz sand, for two replicates, and placed into a ventilation cabinet to evaporate the cosolvent (THF) overnight. Once the THF had evaporated completely, the percentage recovery of the test substance was determine as 105% and 102%, which revealed that the test substance had no obvious loss during volatilisation of THF.
The cosolvent control showed no significant difference of germination and root length in the blank and cosolvent control.
Under the present conditions of the study, the EC50 of germination and root elongation inhibition rates of the 10 seeds were all greater than 1000 mg/L. The inhibition effect of the test substance to seeds was not significant.
Results with reference substance (positive control):
Not applicable
Reported statistics and error estimates:
The germination, root length, standard deviation, inhibition rates of germination and root length in each group were calculated. The T-test was performed to compare the treatment groups with the control. There are significant differences between the treatment and control groups when p < 0.05. Otherwise, there are no significant differences between the treatments and the control groups.
Validity criteria fulfilled:
yes
Conclusions:
Under the present conditions of the study, the results revealed that the EC50 of germination and root elongation inhibition rates of the 10 seeds were all greater than 1000 mg/L. Therefore, there were no significant inhibition effects of the test substance to seeds.
Executive summary:

The purpose of the study was to evaluate the inhibition effect of the test substance on seed germination and root elongation toxicity of the test species after the seeds were exposed to a series of concentrations of the test substance over the test period and develop data on the phytotoxicity of the test substance.

Test seeds were exposed to a series of test concentrations (5 mg/L, 10 mg/L, 50 mg/L, 100 mg/L, 500 mg/L and 1000 mg/L) of the test substance. The test period ended when at least 65% of the control seeds have germinated and developed roots at least 20 mm long. When both conditions were met, the mean number of seed germinating and mean root length per treatment and control were determined, and the inhibition effect of the test substance was evaluated.

A volume for each test concentration of the prepared test stock solution, with a concentration of 1000 mg/L test substance, was mixed with quartz sand, for two replicates, and placed into a ventilation cabinet to evaporate the cosolvent (THF) overnight. Once the THF had evaporated completely, the percentage recovery of the test substance was determine as 105% and 102%, which revealed that the test substance had no obvious loss during volatilisation of THF.

The cosolvent control showed no significant difference of germination and root length in the blank and cosolvent control.

Under the present conditions of the study, the EC50 of germination and root elongation inhibition rates of the 10 seeds were all greater than 1000 mg/L. The inhibition effect of the test substance to seeds was not significant.

Description of key information

Under the present conditions of the study, the EC50 of germination and root elongation inhibition rates of the 10 seeds were all greater than 1000 mg/L. The inhibition effect of the test substance to seeds was not significant.

Key value for chemical safety assessment

Short-term EC50 or LC50 for terrestrial plants:
1 000 mg/kg soil dw

Additional information