5,7-dichloro-4-(4-fluorophenoxy)quinoline;quinoxyfen (ISO)

Toxicity to terrestrial plants

Link to relevant study record(s)

Reference

Endpoint:

toxicity to terrestrial plants: long-term

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

There are two long-term studies (21-day seedling emergence and 21-d vegetative vigour test) available for quinoxyfen exposed via a formulation summarised in one robust study summary. The formulation used in the studies contained only quinoxyfen as an active ingredient and the co-formulants were not considered to reduce the toxicity but rather ensure a worst-case exposure scenario (ensuring exposure to quinoxyfen is maximised).

According to the ECHA Chapter R7c, section R.7.11.3.1 (2017), the most suitable study for chemicals likely to reach the soil via sewage sludge is the seedling emergence study (OECD TG 208, comparable to EPA OPPTS (now OCSPP) 850.4100 and 850.4225). The seedling emergence study is most relevant for this REACH registration, since the most likely route of exposure is via sewage sludge rather than atmospheric deposition (the test item has a low vapour pressure and no uses are registered other than manufacture and formulation into products). Therefore, the endpoint from the seedling emergence study is used for risk assessment purposes. The registered substance was applied on the soil via spray application and the results are reported as g quinoxyfen/ha, but it is possible to calculate the worst-case concentration in mg quinoxyfen/kg dw soil assuming a standard soil bulk density of 1.5 g/cm3 and a soil depth of 5 cm. The results of the vegetative vigour test have been included for completeness, but due to the reasons discussed above the results are not used in risk assessment.

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.4100 (Terrestrial Plant Toxicity Tier I (seedling emergence))

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.4150 (Terrestrial Plant Toxicity Tier I (vegetative vigor))

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.4225 (Seedling Emergence Tier II)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.4250 (Vegetative Vigor Tier II)

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

- Substance ID: TSN 102057
- Name of substance: EF-1295
- Lot#: OA11272018
EF-1295 is a formulation (SC - suspension concentrate) containing 251 g/L Quinoxyfen

Analytical monitoring:

no

Vehicle:

yes

Remarks:

deionized water

Species:

Beta vulgaris

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Sugarbeet
- Plant family: Chenopodiaceae
- Variety: Beta 5296
- Source of seed: Betaseed

Species:

Cucumis sativus

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Cucumber
- Plant family: Cucurbitaceae
- Variety: Straight Eight
- Source of seed: Chesmore Seed Co.

Species:

Helianthus annuus

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Sunflower
- Plant family: Compositae
- Variety: 231
- Source of seed: Novartis Seed.

Species:

Raphanus sativus

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Radish
- Plant family: Cruciferae
- Variety: Crimson Giant
- Source of seed: Chesmore Seed Co.

Species:

Glycine max (G. soja)

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Soy bean
- Plant family: Leguminosae
- Variety: Williams 82
- Source of seed: Missouri Foundation Seed

Species:

Lycopersicon esculentum

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Tomato
- Plant family: Solanaceae
- Variety: Beefsteak
- Source of seed: Henry Field Seed Co.

Species:

Zea mays

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Corn
- Plant family: Graminae
- Variety: N3030BT
- Source of seed: Novartis Seed

Species:

Triticum aestivum

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Wheat
- Plant family: Graminae
- Variety: Roane
- Source of seed: Virginia Crop Imp Assoc

Species:

Allium cepa

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Onion
- Plant family: Amaryllidaceae
- Variety: Hybrid Candy
- Source of seed: Henry Field's seed Co

Species:

other: Echinochloa crus-galli

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Barnyard grass
- Plant family: Graminae
- Source of seed: Valley Seed Service

Test type:

seedling emergence toxicity / vegetative vigour test

Study type:

other: greenhouse study

Substrate type:

natural soil

Remarks:

Single application

Test temperature:

The greenhouse temperatures ranged from a high of 37 to a low of 18°C.

pH:

6.4

Moisture:

17% (1/3 bar)

Nominal and measured concentrations:

The test substance was tested as a typical end use suspension concentrate formulation, at 600 g a.i./ha (cucumber was tested at additional rates of 300, 150, and 75 g/ha).

Reference substance (positive control):

no

Key result

Species:

other: For all the species tested

Duration:

3 wk

Effect conc.:

600 g/ha

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

seedling emergence

Remarks on result:

other: did not result in a significant reduction in fresh weight, length, or injury

Key result

Species:

other: For all species tested (except cucumber)

Duration:

3 wk

Effect conc.:

600 g/ha

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: vegetative vigor

Remarks on result:

other: greater than 20% response in injury and fresh weight was not observed

Key result

Species:

Cucumis sativus

Duration:

3 wk

Dose descriptor:

NOEC

Effect conc.:

75 g/ha

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: fresh weight

Key result

Species:

Cucumis sativus

Duration:

3 wk

Dose descriptor:

EC25

Effect conc.:

424 g/ha

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: fresh weight

Key result

Species:

Cucumis sativus

Duration:

3 wk

Dose descriptor:

EC50

Effect conc.:

> 600 g/ha

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: fresh weight

Key result

Species:

Cucumis sativus

Duration:

3 wk

Dose descriptor:

EC25

Effect conc.:

419 g/ha

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: injury

Key result

Species:

Cucumis sativus

Duration:

3 wk

Dose descriptor:

EC50

Effect conc.:

> 600 g/ha

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: injury

Validity criteria fulfilled:

yes

Conclusions:

NOEC (cucmber fresh weight) = 75 g/ha
EC25 (cucmber fresh weight) = 424 g/ha
EC50 (cucmber fresh weight) > 600 g/ha

EC25 (cucmber injury) = 419 g/ha
EC50 (cucmber fresh weight) > 600 g/ha

Executive summary:

A Tier I/II terrestrial non-target seedling emergence and vegetative vigor greenhouse study with the test substance was conducted on six dicot (cucumber, radish, soybean, sugarbeet, sunflower, and tomato) and four monocot (barnyard grass, corn, onion, and wheat) species. The objective of the study was to determine the effect of the test substance on the emergence and early growth of non-target plants, meeting the requirements under the proposed Ecological Effects Test Guidelines OPPTS; 850.4100, 850.4150, 850.4225, 850.4250 (previously Subdivision J: Tier I (122-1) Tier II (123-1)).

The test substance was tested as EF-1295, a typical end use suspension concentrate formulation, at 600 g a.i./ha (cucumber was tested at additional rates of 300, 150, and 75 g/ha). The test substance contained only one active (quinoxyfen). Application was made using an overhead track sprayer in approximately 210 L/ha (22 gal/A) spray volume. Plants were in the 1-4 leaf growth stage for the vegetative vigor tests, and seeds were planted within 24 hours prior to the application in the seedling emergence test. Approximately 2-3 weeks after treatment application, plants were rated for emergence, visual injury, height, and fresh weight.

In the emergence test there were no injury, length or fresh weight reductions greater than 20% due to the treatment. In the vegetative vigor test, cucumber was the only species showing a greater than 20% response in injury and fresh weight. For cucumber fresh weight the NOEC was 75 g/ha, the EC25 was 424 g/ha and the EC50 was >600 g/ha. For cucumber injury the EC25 was 419 g/ha and the EC50 was >600 g/ha.

Description of key information

21-day NOEC (seedling emergence) = 600 g quinoxyfen/ha = 0.8 mg quinoxyfen/ kg dw exposed as a formulation (EF-1295). OPPTS; 850.4100 and850.4225; Reliability = 1.

Key value for chemical safety assessment

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

0.8 mg/kg soil dw