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Toxicity to terrestrial plants

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Endpoint:
toxicity to terrestrial plants: long-term
Type of information:
experimental study
Adequacy of study:
key study
Study period:
25 Feb - 25 Apr 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 208 (Terrestrial Plants, Growth Test)
Version / remarks:
adopted 19 July 2006
Deviations:
yes
GLP compliance:
yes (incl. certificate)
Remarks:
Department of Health of the Government of the United Kingdom
Analytical monitoring:
no
Remarks:
The verification of the concentration is provided by the recorded weights of the test item added to the soil.
Vehicle:
no
Details on preparation and application of test substrate:
- Method of mixing into soil: The test substance was applied to dry soil and mixed using a pestle and mortar and mixed into the appropriate amount of weighed moist soil. Afterwards this soil was then moistened with reverse osmosis (RO) water and mixed using a handheld mixer.
- Controls: For untreated water controls, the same amounts of dry soil and moist soil was used as for the treatment groups. For the water control the dry soil was mixed into the moist soil. Water was then added as for the treated groups.
- Details: Please see detailed information concerning test item preparation within tables 1-3 in section "Any other information on matrial and methods incl tables".
Species:
Brassica oleracea var. capitata
Plant group:
Dicotyledonae (dicots)
Details on test organisms:
- Common name: Cabbage
- Plant family: Cruciferae (Brassicaceae)
- Source of seed: Purchased from commercial suppliers
- Prior seed treatment/sterilization: Seeds were not treated with any type of fungicides, insecticides, or any other type of pesticidal compound.
- Historical germination of seed (germination of seed lot tested): Emergence trials indicated that seed viability was ≥ 75% for all species.
- Seed storage: Dry in glass bottles and kept in darkness prior to the start of the study.
Species:
Daucus carota
Plant group:
Dicotyledonae (dicots)
Details on test organisms:
- Common name: Carrot
- Plant family: Apiaceae (Umbelliferae)
- Source of seed: Purchased from commercial suppliers
- Prior seed treatment/sterilization: Seeds were not treated with any type of fungicides, insecticides, or any other type of pesticidal compound.
- Historical germination of seed (germination of seed lot tested): Emergence trials indicated that seed viability was ≥ 75% for all species.
- Seed storage: Dry in glass bottles and kept in darkness prior to the start of the study.
Species:
Lactuca sativa
Plant group:
Dicotyledonae (dicots)
Details on test organisms:
- Common name: Lettuce
- Plant family: Asteraceae (Compositae)
- Source of seed: Purchased from commercial suppliers
- Prior seed treatment/sterilization: Seeds were not treated with any type of fungicides, insecticides, or any other type of pesticidal compound.
- Historical germination of seed (germination of seed lot tested): Emergence trials indicated that seed viability was ≥ 75% for all species.
- Seed storage: Dry in glass bottles and kept in darkness prior to the start of the study.
Species:
Lycopersicon esculentum
Plant group:
Dicotyledonae (dicots)
Details on test organisms:
- Common name: Tomato
- Plant family: Solanaceae
- Source of seed: Purchased from commercial suppliers
- Prior seed treatment/sterilization: Seeds were not treated with any type of fungicides, insecticides, or any other type of pesticidal compound.
- Historical germination of seed (germination of seed lot tested): Emergence trials indicated that seed viability was ≥ 75% for all species.
- Seed storage: Dry in glass bottles and kept in darkness prior to the start of the study.
Species:
Avena sativa
Plant group:
Monocotyledonae (monocots)
Details on test organisms:
- Common name: Oat
- Plant family: Poaceae (Gramineae)
- Source of seed: Purchased from commercial suppliers
- Prior seed treatment/sterilization: Seeds were not treated with any type of fungicides, insecticides, or any other type of pesticidal compound.
- Historical germination of seed (germination of seed lot tested): Emergence trials indicated that seed viability was ≥ 75% for all species.
- Seed storage: Dry in glass bottles and kept in darkness prior to the start of the study.
Species:
Allium cepa
Plant group:
Monocotyledonae (monocots)
Details on test organisms:
- Common name: Onion
- Plant family: Liliaceae (Amarylladaceae)
- Source of seed: Purchased from commercial suppliers
- Prior seed treatment/sterilization: Seeds were not treated with any type of fungicides, insecticides, or any other type of pesticidal compound.
- Historical germination of seed (germination of seed lot tested): Emergence trials indicated that seed viability was ≥ 75% for all species.
- Seed storage: Dry in glass bottles and kept in darkness prior to the start of the study.
Test type:
seedling emergence and seedling growth test
Study type:
laboratory study
Substrate type:
natural soil
Limit test:
yes
Total exposure duration:
21 d
Remarks:
Plants were harvested 14 - 18 days after 50% control germination, giving a total exposure period of 21 days for all species.
Test temperature:
18.8 - 24.6 °C (mean range for all species)
pH:
8.1 - 8.2 (control
8.4 (1000 mg/kg dw)
Moisture:
51.33 – 81.22% rel. humidity (mean range for all species)
Details on test conditions:
TEST SYSTEM
- Test container: 10.5 cm internal diameter plastic pots
- Amount of soil: Approximately 75 mm
- Method of seeding: The seeds were spaced out on the soil surface and approximately 10 mm of soil was added to cover the seeds.
- No. of seeds per container: 7 pots for cabbage, carrot and lettuce; 10 pots for tomato; 5 pots for oat and onion
- No. of replicates per treatment group: 7 pots of three seeds for cabbage, carrot and lettuce; 10 pots of two seeds for tomato; 5 pots of four seeds each for oat and onion
- No. of replicates per control: 7 pots

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Geographic location: Soil batch GIL1401
- Pesticide use history at the collection site: Soil was not treated with pesticides in the year of sampling or two previous years.
- Collection procedures: Sieved prior to use to remove all particles >2 mm
- % sand: 79% w/w
- % silt: 10% w/w
- % clay: 11% w/w
- Soil taxonomic classification: Sandy loam
- Soil classification system: According to UK classification
- Organic carbon (%): 1.1% w/w (by wet oxidation)
- Pretreatment of soil: Not pasteurized, or heat treated before use and was not treated with pesticides in the year of sampling or two previous years.
- Available potassium: 93.8 mg/L
- Total potassium: 784 mg/kg
- Organic matter (%): 1.89%

GROWTH CONDITIONS
- Photoperiod: 16 hours light per day
- Light intensity and quality:
Cabbage: 6170 - 10710 lux
Carrot: 6710 - 10740 lux
Lettuce: 5340 - 8830 lux
Tomato: 6210 - 9940 lux
Oat: 6170 - 14300 lux
Onion: 7880 - 12940 lux
- Day/night temperatures: 15.3 – 28.9 °C (range)
- Relative humidity (%): 28.07 – 91.37% (range)
- Watering regime and schedules: Plants were watered as required, maintaining seedling health and growth (visually determined on a per-species and per-treatment basis)

EFFECT PARAMETERS MEASURED: Each pot was inspected daily, the number of emerged plants was recorded, together with any herbicidal symptoms.

- Phytotoxicity rating system: Assessment was conducted using a uniform scoring system based on plant size and vigor where 0 indicated no abnormal effects and 10 for all plants within a replicate being dead.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: no due to limittest
Range finding study
- Test concentrations: 0; 0.1; 1.0; 10; 100; 1000 mg a.i./kg dry soil
- Results used to determine the conditions for the definitive study:
Nominal and measured concentrations:
control and 1000 mg a.i./kg dry soil
Reference substance (positive control):
no
Species:
other: all species tested
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
>= 1 000 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
germination
Species:
other: all species tested
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
>= 1 000 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
seedling emergence
Species:
other: all species tested
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
>= 1 000 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
other: survival
Species:
other: all species tested
Duration:
21 d
Dose descriptor:
EC50
Effect conc.:
> 1 000 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
other: survival and seedling emergence
Species:
other: all species tested
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
1 000 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth
Species:
other: all species tested
Duration:
21 d
Dose descriptor:
EC50
Effect conc.:
> 1 000 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth
Species:
other: all species tested
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
1 000 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
phytotoxicity
Details on results:
SEED GERMINATION
- Percent seed germination: Germination was recorded daily until there was >50% in the water controls. There were no effects on germination in any species. The NOEC for germination of these species was therefore ≥ 1000 mg a.i./kg dry soil. All seeds germinated.

SEEDLING EMERGENCE
- Percent seedling emergence: 100%
- Percent survival: There were no treatment-related effects on plant survival with 100% plant survival in both the control and treatment rate in all species.
- Other effects: A visual assessment based on the overall condition of surviving seedlings for each replicate was conducted at the end of the study and at regular intervals throughout. No signs of phytotoxicity were observed in the treatment group compared to the control group. The NOEC for phytotoxicity was therefore ≥ 1000 mg a.i./kg dry soil.

Reported statistics and error estimates:
Statistical analysis of and mean replicate height and wet weight were carried out using the SAS 9.1.3 programme (SAS Institute Inc. 2002). Statistical analysis of the height and wet weights of cabbage, carrot, lettuce, tomato and oat, in comparison to the water control, was carried out using the t-test. The wet weight data was log transformed prior to analysis to stabilize the variance and the means are presented as back transformed geometric means.

Table 1: Germination and survival

Species

Treatment

Application rate (mg a.i./kg dry soil)

Number germinated (a)

Plant germination (%)

% reduction in germination

Total number of surviving plants evaluated at final assessment

Survival (%)

Cabbage

Water control

0

21

100

0

21

100

 

Test item

1000

21

100

0

21

100

Carrot

Water control

0

21

100

0

21

100

 

 Test item

1000

21

100

0

21

100

Lettuce

Water control

0

21

100

0

21

100

 

Test item

1000

21

100

0

21

100

Tomato

Water control

0

20

100

0

20

100

 

Test item

1000

20

100

0

20

100

Oat

Water control

0

20

100

0

20

100

 

Test item

1000

20

100

0

20

100

Onion

Water control

0

20

100

0

20

100

 

Test item

1000

20

100

0

20

100

a n = 21 for cabbage, carrot and lettuce, 20 for tomato, oat and onion

 

Table 2: Percent Reduction in Height in Comparison to the Water Control

Plant

Treatment

Rate (mg a.i./kg dry soil)

Geometric mean

% increase (+) or reduction (-) in mean height

p

Cabbage

Water control

0

4.121

0 –

 

 

Test item

1000

4.155

0.8+

0.908

Carrot

Water control

0

1.864

0

-

 

Test item

1000

1.870

0.3+

0.954

Lettuce

Water control

0

0.935

0

-

 

Test item

1000

0.981

4.9+

0.467

Tomato

Water control

0

4.730

0

-

 

Test item

1000

4.877

3.1+

0.530

Oat

Water control

0

39.123

0

-

 

Test item

1000

40.059

2.4+

0.211

Onion

Water control

0

13.257

0

-

 

Test item

1000

13.290

0.2+

0.965

p values are for the comparison with water control using the t-test; 0: No reduction

 

Table 3: Percent Reduction in wet weight in Comparison to the Water Control

Plants

Treatment

Rate (mg a.i./kg dry soil)

Geometric mean

% increase (+) or reduction (-) in mean wet weight

p

Cabbage

Water control

0

665.88

0

 

 

Test item

1000

668.48

0.4+

0.955

Carrot

Water control

0

74.656

0

 

 

Test item

1000

76.004

1.8+

0.843

Lettuce

Water control

0

474.83

0

 

 

Test item

1000

499.57

5.2+

0.674

Tomato

 Water control

0

776.53

0

 

 

Test item

1000

808.27

4.1+

0.687

Oat

Water control

0

1032.0

0

 

 

Test item

1000

1033.4

0.1+

0.973

Onion

Water control

0

159.65

0

 

 

Test item

1000

160.28

0.4+

0.952

p values are for the comparison with water control using the t-test; 0: No reduction

Validity Criteria

Table 4: Validity criteria for OECD 208

Criterion from the guideline

Outcome

Validity criterion fulfilled

Seedling emergence is at least 70%

100%

Yes

Seedlings do not exhibit visible phytotoxic effects and the plants exhibit only normal variation in growth and morphology for that

particular species

No effects were observed

Yes

mean survival of emerged control seedlings is at least 90% for the duration of the study

>90%

Yes

environmental conditions for a particular species are identical and growing media contain the same

amount of soil matrix, support media, or substrate from the same source

Yes

Yes

Validity criteria fulfilled:
yes
Remarks:
For further details please see Table 4 within the section “Any other information on results incl. tables”.
Conclusions:
There was no effect on the emergence or survival of any of the species tested following application of test item at 1000 mg a.i./kg dry soil. The NOEC for both these parameters was >= 1000 mg a.i./kg dry soil for all species. The EC50 values were estimated to be >1000 mg a.i./kg dry soil for all species. There were no statistically significant adverse treatment related effects in the height or wet weight of any species in comparison to the water control following application of test item at 1000 mg a.i./kg dry soil. The NOEC values for effects on height and wet weight were >= 1000 mg a.i./kg dry soil for all species. The EC50 values were estimated to be >1000 mg a.i./kg dry soil for all species. No signs of phytotoxicity were observed in the treatment groups or in either the water or solvent control groups. The study was considered valid as the validation criteria were met and no visible phytotoxic effects were observed in the controls.

Description of key information

NOEC (21 d) ≥1000 mg/kg dry soil (Seeding emergence, OECD 208, all tested species, nominal)

Key value for chemical safety assessment

Long-term EC10, LC10 or NOEC for terrestrial plants:
1 000 mg/kg soil dw

Additional information

The effects of Reaction mass of 1,1'-(isopropylidene)bis[3,5-dibromo-4-(2,3-dibromo-2-methylpropoxy)benzene] and 1,3-dibromo-2-(2,3-dibromo-2-methylpropoxy)-5-{2-[3,5-dibromo-4-(2,3,3-tribromo-2-methylpropoxy)phenyl]propan-2-yl}benzene (EC 944-461-4) to plants was investigated in a seedling emergence and seedling growth study by Taylor (2018) according to OECD guideline 208 and GLP. The test was performed with four Dicotyledons (Brassica oleracea, Daucus carota, Lactuca sativa, Lycopersicon esculentum) and two Monocotyledons (Avena sativa and Allium cepa). Based on the results of a range-finding test all plants were exposed to a single nominal concentration of 1000 mg/kg dry soil for 21 d. A total of 7 pots of three seeds each were sown for cabbage, carrot and lettuce, 10 pots of two seeds each for tomato and 5 pots of four seeds each for oat and onion for each application rate of the test item and the water controls. The soil used was a sandy loam, sieved to remove all particles > 2 mm. After application and sowing, the pots were checked daily and the numbers of emerged seedlings were recorded. Emergence, survival and sub-lethal effects were recorded daily up to a minimum of 50% emergence of control seedlings and thereafter every one to three days. Plants were harvested 14 - 18 days after 50% control germination, giving a total exposure period of 21 days for all species. The height of each individual plant was then measured before the plants were weighed to obtain a measurement of wet weight. Analytical verification of the concentration was provided by the recorded weights of the test item added to the soil. Statistical analysis of data was performed to obtain NOEC, LOEC and EC50 values for germination, survival, height and biomass (wet weight), using the SAS 9.1.3 program for statistical analysis (SAS Institute Inc. 2002). Since no effects were observed in any plant and for any parameter, the overall NOEC was observed to be ≥1000 mg/kg dry soil.