N-[2,5-dichloro-4-(1,1,2,3,3,3-hexafluoropropoxy)-phenyl-aminocarbonyl]-2,6-difluorobenzamide

Toxicity to terrestrial plants

Link to relevant study record(s)

Reference

Endpoint:

toxicity to terrestrial plants: short-term

Type of information:

experimental study

Adequacy of study:

key study

Study period:

28 Sep 2002 - 11 Nov 2002

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 208 (Terrestrial Plants Test: Seedling Emergence and Seedling Growth Test)

Version / remarks:

Draft guidance

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Details on preparation and application of test substrate:

- Method of application to soil surface: All the treatments were applied with a laboratory sprayer with a nozzle. The sprayer was set to deliver an output of 500 L/ha by applying an air pressure of 3 bar. Before application, spray patterns were checked visually for uniformity. Different concentrations of the same substance were applied in order of rising concentrations, and the sprayer was rinsed before the treatment was made. Before and after applications with different substances, the sprayer was cleaned with water and an acetone—water solution.

The stock solutions were prepared just before treatment application with the test item by mixing varying amounts of primary stock solution with deionised water.

Species:

Glycine max (G. soja)

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Soybean
- Historical germination of seeds: > 90 %

Species:

Brassica napus

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Oilseed rape
- Historical germination of seeds: > 90 %

Species:

Beta vulgaris

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Sugar beet
- Historical germination of seeds: > 90 %

Species:

Allium cepa

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Onion
- Historical germination of seeds: > 90 %

Species:

other: Avena fatua

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Wild oat
- Historical germination of seeds: > 90 %

Species:

Cucumis sativus

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Cucumber
- Historical germination of seeds: > 90 %

Test type:

seedling emergence toxicity / vegetative vigour test

Study type:

laboratory study

Substrate type:

natural soil

Limit test:

no

Total exposure duration:

27 d

Remarks:

Total exposure for Seedling emergence experiment: 27 days after application; Total exposure for Vegetative vigour: 20 days after application

Test temperature:

B. napus, B. vulgaris, A. fatua and A. cepa: minimum temperature of 15 °C during the night and 20 °C during daytime;
C. sativus and G. max: 18 °C during night and 25 °C during daytime

pH:

7.5

Details on test conditions:

TEST SYSTEM

Seedling emergence: Seeds were planted in a mineral soil contained in 10 cm deep plastic trays. The soil allowed good germination without crusting or damping off of the plants. Approximately three seeds of C. sativus and G. max five seeds of B. vulgaris, six seeds of A. fatua and 20 seeds of B. napus and A. cepa were sown per tray 10 cm deep. Plants were watered from the top of the trays as needed. Nutrients were supplied twice a week with a 1:400 w/v dilution of a fertiliser.

Vegetative vigour: Seeds were planted prior to application of the test item in a mineral soil contained in 10 cm deep plastic trays. Approximately three seeds of C. sativus and G. max, five seeds of B. vulgaris, six seeds of A. fatua and 20 seeds of B. napus and A. cepa were sown per tray 10 cm deep. Plants were watered from the top of the trays as needed. Nutrients were supplied twice a week with a 1:400 w/v a fertiliser.

- No. of replicates per treatment group: 1
- No. of replicates per control: 1
- Application rate: 31.25, 62.5, 125, 250, 500 and 1000 mL formulation/ha (corresponding to 1.5, 3.1, 6.25, 12.5, 25 and 50 g/ha, or 0.002, 0.0041, 0.0083, 0.017, 0.033 and 0.067 mg/kg dw soil, respectively)

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
Clay loam from local origin containing 26 % clay, 34 % silt and 40 % sand. The content of organic matter was 2.6 %. The pH of the soil was 7.5.

GROWTH CONDITIONS
- Photoperiod: A photoperiod of 14 hours light per day was maintained by using additional artificial lighting whenever the daylight intensity dropped below 10000 lux.
- Relative humidity (%): 40 to 60

ACCLIMATION PERIOD: Plants used for the vegetative vigour tests were grown for 17 or for 14 days (depending on the plant species) prior to the application of the test item. The growth stage of the plants at the time of application was 2 to 4 leaves. Plants used for seedling emergence tests were watered within 24 hours prior to the application of the test items.

EFFECT PARAMETERS MEASURED:
Seedling emergence: Visual phytotoxicity ratings were recorded 27 days after the application of the test item.
Vegetative vigour: Visual phytotoxicity ratings were recorded 20 days after the application of the test item (i.e. 27 to 30 days after planting).
Evaluation of phytotoxicity was done by visual observations and recording 0% to 100% inhibition of emergence or plant injury .

- Phytotoxicity rating system:
> Rating "10": is as exactly 100% plant injury (dead) or 100% of germination
> Rating "5": to an estimated 50% injury or germination inhibition
> Rating "0": stands for exactly 0% observable effects, thus the appearance of the treated plants/pots is identical to the one of the untreated
> The remaining values are aimed at 10% steps with respect to injury or emergence

Nominal and measured concentrations:

Nominal concentrations: 1.5, 3.1, 6.25, 12.5, 25 and 50 g/ha (equivalent to 0.002, 0.0041, 0.0083, 0.017, 0.033 and 0.067 mg/kg dw soil)

Reference substance (positive control):

no

Key result

Species:

other: Allium cepa, Avena fatua, Beta vulgaris, Brassica napus, Cucumis sativus, Glycine max

Duration:

27 d

Dose descriptor:

NOEC

Effect conc.:

50 g/ha

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

seedling emergence

Remarks on result:

other: Equivalent to 0.067 mg/kg dw soil

Key result

Species:

other: Allium cepa, Avena fatua, Beta vulgaris, Brassica napus, Cucumis sativus, Glycine max

Duration:

20 d

Dose descriptor:

NOEC

Effect conc.:

50 g/ha

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth

Remarks on result:

other: Equivalent to 0.067 mg/kg dw soil

Details on results:

Seedling emergence: On Allium cepa, Avena fatua, Beta vulgaris, Brassica napus, Cucumis sativus, Glycine max no effect of the test item could be
detected in all treatments up to 50 g/ha (equivalent to 0.067 mg/kg dw soil)
Vegetative vigour: On Allium cepa, Avena fatua, Beta vulgaris, Brassica napus, Cucumis sativus, Glycine max no effect of the test item could be
detected in all treatments up to 50 g/ha (equivalent to 0.067 mg/kg dw soil)

Table 1. Test substance profiling test –seedling emergence effect ratings

Species	Application rate (mL formulation/ha)
	1000 (50g/ha)	500 (25g/ha)	250 (12.5g/ha)	125 (6.25g/ha)	62.5 (3.1g/ha)	31.25 (1.5g/ha)
Brassica napus	0	0	0	0	0	0
Avena fatua	0	0	0	0	0	0
Beta vulgaris	0	0	0	0	0	0
Cucumis sativus	0	0	0	0	0	0
Glycine max	0	0	0	0	0	0
Allium cepa	0	0	0	0	0	0

 

 

Table 2. Test substance profiling test – vegetative vigour effect ratings

Species	Application rate (mL formulation/ha)
	1000  (50g/ha)	500  (25g/ha)	250  (12.5g/ha)	125  (6.25g/ha)	62.5  (3.1g/ha)	31.25  (1.5g/ha)
Brassica napus	0	0	0	0	0	0
Avena fatua	0	0	0	0	0	0
Beta vulgaris	0	0	0	0	0	0
Zea mays	0	0	0	0	0	0
Glycine max	0	0	0	0	0	0
Allium cepa	0	0	0	0	0	0

 

Validity criteria fulfilled:

yes

Conclusions:

In a seedling emergence and vegetative vigour test that was performed according to an equivalent of OECD 208 in six plant species, no effects of the test substance were observed in any of the test species at rates up to and including 1000 mL/ha (equivalent to 50 g/ha or 0.067 mg/kg dw soil).

Executive summary:

In this study performed according to an equivalent of OECD TG 208 and in compliance with GLP, six species of higher plants, two monocot (onion Allium cepa, oat Avena fatua) and four dicot (sugar beet Beta vulgaris, oilseed rape Brassica napus, cucumber Cucumis sativus, soybean Glycine max) were treated with six test concentrations of test substance formulation and a water control. Seedling emergence following pre-emergent application, and vegetative vigour following post-emergent application, were evaluated separately.

Treatment levels were control (untreated), 31.25, 62.5, 125, 250, 500 and 1000 mL formulation/ha (corresponding to 1.5, 3.1, 6.25, 12.5, 25 and 50 g/ha, respectively), applied in a volume of 500 L/ha using a laboratory sprayer. One replicate per treatment level was sprayed, each with three to approximately 20 seeds of each species, depending on seed size.

Test units were non-porous plastic trays, 10 cm deep, with drainage holes in the bottom and containing a mineral soil. All species were sown together at intervals along one tray (= replicate). Plants were grown in glasshouses with minimum temperature set to 15-18 or 20-25 °C depending on species, relative humidity 40-60% and with a 14 h daily photoperiod. Plants were top-watered as required and a nutrient solution supplied twice a week. Plants used for the seedling emergence test were watered within 24 hours prior to the treatment application. Plants used for the vegetative vigour test were grown for 14 or 17 days (depending on species) prior to treatment application.

Seedling emergence was evaluated 27 days after application. Vegetative vigour was assessed 20 days after application. Phytotoxicity was assessed visually according to a rating scale from 0 to 10: 0 = no observable effects on germination and/or growth, indistinguishable from the untreated control; 5 = estimated 50% inhibition of germination and/or growth; 10 = 100% inhibition of germination or complete destruction of above ground parts.

No effects of the test substance were observed in any of the test species at rates up to and including 1000 mL/ha (equivalent to 50 g/ha or 0.067 mg/kg dw soil).

Description of key information

All available data was assessed. One study was available addressing the toxicity to terrestrial plants and its effects value was used as the key value:

Toxicity to terrestrial plants, NOEC = 50 g/ha (equivalent to 0.067 mg/kg dw soil), absence of effects, equivalent to OECD208, Wälder 2002

Key value for chemical safety assessment

Long-term EC10, LC10 or NOEC for terrestrial plants:

0.067 mg/kg soil dw

Additional information

One study is available for this endpoint, which was selected as key study. In this study performed according to an equivalent of OECD TG 208 and in compliance with GLP, six species of higher plants, two monocot (onion Allium cepa, oat Avena fatua) and four dicot (sugar beet Beta vulgaris, oilseed rape Brassica napus, cucumber Cucumis sativus, soybean Glycine max) were treated with six test concentrations of test substance formulation and a water control. Seedling emergence following pre-emergent application, and vegetative vigour following post-emergent application, were evaluated separately. Treatment levels were control (untreated), 31.25, 62.5, 125, 250, 500 and 1000 mL formulation/ha (corresponding to 1.5, 3.1, 6.25, 12.5, 25 and 50 g a.s./ha, respectively), applied in a volume of 500 L/ha using a laboratory sprayer. One replicate per treatment level was sprayed, each with three to approximately 20 seeds of each species, depending on seed size. Plants used for the seedling emergence test were watered within 24 hours prior to the treatment application. Plants used for the vegetative vigour test were grown for 14 or 17 days (depending on species) prior to treatment application. Seedling emergence was evaluated 27 days after application. Vegetative vigour was assessed 20 days after application. Phytotoxicity was assessed visually. No effects of the test substance were observed in any of the test species at rates up to and including 1000 mL/ha (equivalent to 50 g/ha or 0.067 mg/kg dw soil).

Metabolites - available information

In addition to the study with the test substance, one study is available with degradation product M6. As the dossier has been prepared to address the test substance itself, this study is not summarized as endpoint study record but is briefly discussed here. In the seedling emergence study with M6, performed in accordance with OECD 208 and in compliance with GLP conditions, an EC50 >1000 mg/kg was established for emergence of growth in the monocot ryegrass (Lolium perenne) after 41 days exposure. In the same study, two dicots were also tested, resulting in EC50 values of >1000 mg/kg and 680 mg/kg in Chinese cabbage (Brassica campestris var. chinesis) and EC50 values of 170 mg/kg and 37 mg/kg in lettuce (Lactuca sativa) for no. of emerged plants and biomass (dry weight), respectively, after 20 days of exposure (Grade, 1999).