Dihexyl ether

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

Study period:

11 August 2022 - 31 October 2022

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

The following deviations from the protocol occurred during the study: • The initial soil analysis was not conducted as part of this study. • The light levels were below the recommended minimum of 300 μmol/m2/s (μE/m2/s) throughout the study. • The humidity fell below the recommended minimum of 45% for all species except cabbage. Minimum humidity recordings were 40% for carrot, tomato, barley and onion and 42% for lettuce.

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

19 July 2006

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Species:

Hordeum vulgare

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Barley
- Plant family: Poaceae
- Variety: KWS Orwell
- Source of seed: KWS

Species:

Allium cepa

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Onion
- Plant family: Liliaceae
- Variety: F1 Toughball
- Source of seed: Moles Seeds

Species:

Lycopersicon esculentum

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Tomato
- Plant family: Solanaceae
- Variety: Alicante
- Source of seed: Moles Seeds

Species:

Lactuca sativa

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Lettuce
- Plant family: Asteraceae
- Variety: Arctic King
- Source of seed: Kings Seeds

Species:

Daucus carota

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Carrot
- Plant family: Apiaceae
- Variety: F1 Norwich
- Source of seed: Moles Seeds

Species:

Brassica oleracea var. capitata

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Cabbage
- Plant family: Brassicaceae
- Variety: Wheelers Imperial
- Source of seed: Moles Seeds

Test type:

seedling emergence and seedling growth test

Study type:

laboratory study

Substrate type:

artificial soil

Limit test:

no

Total exposure duration:

21 d

Remarks:

21 days was the minimum exposure period

Test temperature:

21.0 to 24.9 °C

pH:

7.09 to 7.51

Moisture:

40 - 90 % humidity

Details on test conditions:

TEST SYSTEM
- Testing facility: Smithers ERS Limited
- Test container (type, material, size): 11.5 cm internal diameter round pots, with drainage holes in the base
- Amount of soil: 700 g dry weight per replicate
- No. of seeds per container: 3 (Cabbage, carrot, lettuce and tomato), 4 (Barley and onion)
- No. of replicates per treatment: 7 (Cabbage, carrot, lettuce and tomato), 5 (Barley and onion)
- No. of replicates per control: 5 or 7

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Geographic location: Boughton Loam & Turf Management
- Soil texture (if natural soil):
- % sand: 65
- % silt: 17
- % clay: 18
- Soil taxonomic classification: clay loam soil, but quartz sand was added to produce a sandy loam
- Soil classification system: UK
- Organic carbon (%): 1.3

GROWTH CONDITIONS
- Photoperiod: 16:8 hours light:dark
- Light intensity and quality: 350 ± 50 μmol/m2/sec
- Day/night temperatures: 22 ± 10°C
- Relative humidity (%): 70 ± 25
- Water source/type: Plants were watered, as necessary, using mains water. Initially the pots were surface-watered, with care being taken not to disturb or flood the soil. The pots were then either top or bottom-watered in the individual saucers, as required, to maintain suitable conditions for germination and growth.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Emergence
- Seedling height
- Seedling weight
- Survival
- Phytotoxic effects

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 10
- Test concentrations: 0.1, 1.0, 10, 100, 1000 mg/kg

Nominal and measured concentrations:

0.1, 1.0, 10, 100 1000 mg/kg

Key result

Species:

Allium cepa

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:

Allium cepa

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:

Allium cepa

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

Key result

Species:

Hordeum vulgare

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

100 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth

Species:

Hordeum vulgare

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:

Hordeum vulgare

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

Key result

Species:

Lycopersicon esculentum

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

100 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth

Species:

Lycopersicon esculentum

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:

Lycopersicon esculentum

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

Key result

Species:

Lactuca sativa

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

100 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth

Species:

Lactuca sativa

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:

Lactuca sativa

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

Key result

Species:

Daucus carota

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

100 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth

Species:

Daucus carota

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:

Daucus carota

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

Key result

Species:

Brassica oleracea var. capitata

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

100 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth

Species:

Brassica oleracea var. capitata

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:

Brassica oleracea var. capitata

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

Details on results:

SEEDLING EMERGENCE
- Percent seedling emergence: For cabbage there was 100, 100, 91.7, 100 and 90.5% emergence at rates of 0.1, 1.0, 10, 100 and 1000 mg a.i./kg dry soil in comparison to 90.5% emergence in the water control. For carrot there was 75.0, 100, 91.7, 100 and 90.5% emergence at rates of 0.1, 1.0, 10, 100 and 1000 mg a.i./kg dry soil in comparison to 90.5% emergence in the water control. For lettuce there was 91.7, 83.3, 91.7, 75.0 and 85.7% emergence at rates of 0.1, 1.0, 10, 100 and 1000 mg a.i./kg dry soil in comparison to 100% emergence in the water control. For tomato there was 75.0, 91.7, 83.3, 91.7 and 95.2% emergence at rates of 0.1, 1.0, 10, 100 and 1000 mg a.i./kg dry soil in comparison to 90.5% emergence in the water control. For barley there was 93.8, 93.8, 100, 100 and 100% germination at rates of 0.1, 1.0, 10, 100 and 1000 mg a.i./kg dry soil in comparison to 95.0% emergence in the water control. For onion there was 93.8, 93.8, 100, 93.8 and 95.0% emergence at rates of 0.1, 1.0, 10, 100 and 1000 mg a.i./kg dry soil in comparison to 100% emergence in the water control.
- Percent survival: For cabbage there was 100, 91.7, 100, 100 and 94.7% plant survival at rates of 0.1, 1.0, 10, 100 and 1000 mg a.i./kg dry soil in comparison to 100% in the water control. For carrots there was 100% plant survival at all rates of application and in the water control. For lettuce, there was 100, 100, 90.9, 100 and 100% plant survival at rates of 0.1, 1.0, 10, 100 and 1000 mg a.i./kg dry soil in comparison to 95.2% in the water control. For tomato, there was 100, 100, 90.9, 100 and 100% plant survival at rates of 0.1, 1.0, 10, 100 and 1000 mg a.i./kg dry soil in comparison to 95.2% in the water control. For barley, there was 100% plant survival up to and including 100 mg a.i./kg dry soil and in the water control with 90.0% survival at 1000 mg a.i./kg dry soil. For onion, there was 93.3% survival at 1.0 mg a.i./kg dry soil with no effects at any other rate of application.
- Plant height: For cabbage, reductions in shoot height of 7.55, 8.27, 5.04 and 39.93% were recorded at 0.1, 1.0, 10 and 1000 mg a.i./kg dry soil respectively in comparison to the water control with an increase in height of 1.80% at 100 mg a.i./kg dry soil. For carrots, reductions in shoot height of 15.38, 13.85, 12.31, 19.62 and 12.69% were recorded at of 0.1, 1.0, 10, 100 and 1000 mg a.i./kg dry soil respectively in comparison to the water control. For lettuce, reductions in shoot height of 25.41, 10.27, 8.11, 16.76 and 41.08% were recorded at of 0.1, 1.0, 10, 100 and 1000 mg a.i./kg dry soil respectively in comparison to the water control. For tomato, reductions in shoot height of 2.40, 18.94, 7.43 and 35.97% were recorded at 1.0, 10, 100 and 1000 mg a.i./kg dry soil respectively in comparison to the water control with an increase in height of 8.15% at 0.1 mg a.i./kg dry soil. For barley, reductions in shoot height of 2.35, 0.64 and 37.11% were recorded at 0.1, 10 and 1000 mg a.i./kg dry soil respectively in comparison to the water control with a slight (<0.5%) increase in height at 100 mg a.i./kg dry soil. There was no effect at 1.0 mg a.i./kg dry soil. For onion, reductions in shoot height of 16.14, 9.61, 8.77, 17.07 and 31.25% were recorded at 0.1, 1.0, 10, 100 and 1000 mg a.i./kg dry soil respectively in comparison to the water control.
- Dry weight: For cabbage, increases in dry weight of 40.15, 16.62, 17.82 and 0% were recorded at 0.1, 1.0, 10 and 100 mg a.i./kg dry soil respectively in comparison to the water control. There was a 48.33% decrease in dry weight at 1000 mg a.i./kg dry soil. For carrots, decreases in dry weight of 10.20, 9.64, 11.87 and 28.21% were recorded at 0.1, 1.0, 100 and 1000 mg a.i./kg dry soil respectively in comparison to the water control with an increase of 2.09% at 10 mg a.i./kg dry soil. For lettuce, decreases in dry weight of 20.75, 26.25 and 61.54% were recorded at 1.0, 100 and 1000 mg a.i./kg dry soil respectively in comparison to the water control with increases of 6.02 and 5.02% at 0.1 and 10 mg a.i./kg dry soil respectively. For tomato, increases in dry weight of 49.80 and 24.87 % were recorded at 0.1 and 1.0 mg a.i./kg dry soil respectively in comparison to the water control. There were decreases in dry weight of 1.39, 4.74 and 72.47% at 10, 100 and 1000 mg a.i./kg dry soil respectively. For barley, increases in dry weight of 10.79, 15.05, 14.55 and 12.10% were recorded at 0.1, 1.0, 10 and 100 mg a.i./kg dry soil respectively in comparison to the water control. There was a 51.90% decrease in dry weight at 1000 mg a.i./kg dry soil. For onion, increases in dry weight of 7.02, 8.09 and 0.85% were recorded at 1.0, 10 and 100 mg a.i./kg dry soil respectively in comparison to the water control. There were decreases in dry weight of 8.3 and 22.13% at 0.1 and 1000 mg a.i./kg dry soil respectively.

Reported statistics and error estimates:

Statistical analysis of the data was undertaken using CETIS version 1.8.6.8, based on the nominal test concentrations. The following methods were used;
• A Wilcoxon/Bonferroni Adj Test was used to determine the NOEC and LOEC values for emergence and survival.
• A Bonferroni Adj t Test was used to determine the NOEC and LOEC values for height and dry weight (biomass) for all test species.
• A Linear Interpolation Test was used to determine the EC20, EC25 and EC50 for height and dry weight (biomass) for all test species.

Validity criteria fulfilled:

yes

Conclusions:

The predominant visual effect in all species was growth inhibition.
Overall there were no significant effects on emergence or survival for any of the six species tested. The NOEC was 1000 mg/kg dry soil in all species for emergence and survival. The NOEC for shoot biomass was 100 mg/kg dry soil for Cabbage, Carrot, Lettuce, Tomato and Barley. For Onion, the shoot biomass NOEC was 1000 mg/kg dry soil.

Executive summary:

Six species were exposed to Dihexyl Ether in an OECD Guideline 208 Terrestrial Plant Test (Seedling Emergence and Growth Test). The six species tested were Cabbage, Carrot, Lettuce, Tomato, Barley and Onion. Growth inhibition was the most sensitive endpoint with NOECs of 100 mg/kg dry soil for Cabbage, Carrot, Lettuce, Tomato and Barley. Onion was less sensitive and the NOEC was 1000 mg/kg dry soil.

Description of key information

In an OECD 208 guideline study, the NOEC was 1000 mg/kg dry soil in all species for emergence and survival for dihexyl ether. The NOEC for shoot biomass was 100 mg/kg dry soil for Cabbage, Carrot, Lettuce, Tomato and Barley. For Onion, the shoot biomass NOEC was 1000 mg/kg dry soil.

Key value for chemical safety assessment

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

100 mg/kg soil dw

Additional information

Six species were exposed to Dihexyl Ether in an OECD Guideline 208 Terrestrial Plant Test (Seedling Emergence and Growth Test). The six species tested were Cabbage, Carrot, Lettuce, Tomato, Barley and Onion. Growth inhibition was the most sensitive endpoint with NOECs of 100 mg/kg dry soil for Cabbage, Carrot, Lettuce, Tomato and Barley. Onion was less sensitive and the NOEC was 1000 mg/kg dry soil.