Phosphoric acid, mono- and di-C16-18-alkyl esters

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:

14 September 2017 to 30 September 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

Physical State/Appearance: White waxy solid
Purity: 100%
Storage Conditions: Room temperature in the dark

Analytical monitoring:

no

Details on sampling:

A total of 14 pots of three seeds each were sown for cabbage, carrot and lettuce, 20 pots of two seeds each for tomato, and ten pots of four seeds each for oat and onion. For all species, 9.5 cm internal diameter plastic pots were used and each was filled to a depth of approximately 75 mm, the seeds were spaced out on the soil surface and approximately 5 mm of soil was added to cover the seeds. Each pot was labelled with the study number, species name, treatment, rate of application, replicate number, application date and the name of the Study Director. Each application rate was also identified by a color-coded plastic stick label. After application each pot was placed in an individual water tray and placed at random within rectangular blocks of evenly spaced pots for each plant species.

Vehicle:

yes

Remarks:

Acetone

Details on preparation and application of test substrate:

The water and solvent controls were applied for all species before the treatment solutions were applied at 4.1, 12.4, 37.0, 111.1 and 333.3 mg a.i./kg dry soil (for tomato) or 1000 mg a.i./kg dry soil (for cabbage, oat, carrot, onion, and lettuce).

The solvent solutions were applied to dry soil and when the acetone had evaporated, the soil was mixed into the appropriate amount of weighed moist soil. This soil was then moistened with reverse osmosis (RO) water and mixed using a handheld mixer to ensure that the soil had a structure suitable for sowing the seeds.

The treated soil was then distributed among labelled replicate pots. For the untreated water and solvent control groups 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 and for the solvent control the appropriate volume of acetone was added and allowed to evaporate off. Water was then added as for the treated groups. The pH of the soil was recorded after application.

Species:

Brassica oleracea var. capitata

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

Cruciferae (Brassicaceae)

Species:

Daucus carota

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

Apiaceae (Umbelliferae)

Species:

Lactuca sativa

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

Asteraceae (Compositae)

Species:

Lycopersicon esculentum

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

Asteraceae (Compositae)

Species:

Avena sativa

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

Poaceae (Gramineae)

Species:

Allium cepa

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

Liliaceae (Amarylladaceae)

Test type:

seedling emergence and seedling growth test

Study type:

laboratory study

Substrate type:

natural soil

Total exposure duration:

21 d

Test temperature:

22°C +/- 10°C

pH:

6.6 - 7.0

Moisture:

13.75%

Details on test conditions:

Prior to treatment the moisture content of the soil was determined to be 13.75% and the appropriate amount of moist soil was weighed out: – 11,603 g for each treatment of cabbage and oat, 11,603 g for each treatment of carrot and onion, 6,768 g for each treatment rate of lettuce and 9,669 g for each treatment of tomato. Aliquots of dry soil (3,000 g for cabbage and oat, 3,000 g for carrot and onion, 1,750 g for lettuce and 2,500 g for tomato) were also weighed out, to give a total weight equivalent to 13,200 g for cabbage and oat, 13,200 g for carrot and onion and 7,700 g for lettuce and 11,000 g for tomato.

Nominal and measured concentrations:

Based on the results of the range finding, a definitive dose-response test was conducted at nominal rates of 4.1, 12.4, 37.0, 111.1, 333.3 and 1000 mg a.i./kg dry soil for tomato, and a limit test at 1000 mg a.i./kg dry soil was conducted for cabbage, carrot, lettuce, onion and oat.

Reference substance (positive control):

no

Key result

Species:

Brassica campestris var. chinensis

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: Germination, survival, height and dry weight

Key result

Species:

Brassica campestris var. chinensis

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

ca. 1 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

other: Germination, survival, height and dry weight

Key result

Species:

Daucus carota

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: Germination, survival, height and dry weight

Key result

Species:

Daucus carota

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

ca. 1 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

other: Germination, survival, height and dry weight

Key result

Species:

Lactuca sativa

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: Germination, survival, height and dry weight

Key result

Species:

Lactuca sativa

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

ca. 1 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

other: Germination, survival, height and dry weight

Key result

Species:

Lycopersicon esculentum

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: Germination, survival, height and dry weight

Key result

Species:

Lycopersicon esculentum

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

ca. 1 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

other: Germination, survival, height and dry weight

Key result

Species:

Avena sativa

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: Germination, survival, height and dry weight

Key result

Species:

Avena sativa

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

ca. 1 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

other: Germination, survival, height and dry weight

Key result

Species:

Allium cepa

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Germination, survival, height and dry weight

Key result

Species:

Allium cepa

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

ca. 1 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Germination, survival, height and dry weight

Details on results:

Germination in the water control was 100% for cabbage, carrot, lettuce, oat and onion and was 93.8% for tomato.

Germination in the solvent control was 100% for cabbage, carrot, lettuce, and onion and 93.8% for tomato and oat.

For cabbage, a 13% reduction in germination was observed at both 1 and 100 mg a.i./kg dry soil, with 93.3% survival at 1000 mg a.i./kg dry soil in comparison to the solvent control. The one plant out of three which died in one replicate at the 1000 mg a.i./kg dry soil was not considered to be biologically significant, with 100% survival at all lower treatment rates.

For carrot, 13% and 7% reductions in germination were observed at 0.1 and 1 mg a.i./kg dry soil respectively in comparison to the solvent control, with 100% survival at all treatment rates.

For tomato, 6%, 12.5% and 12.5% reduction in germination were observed at 0.1, 1 and 1000 mg a.i./kg dry soil respectively in comparison to the solvent control, with 100% survival at all treatment rates.

There were no treatment related effects on germination of cabbage, carrot and tomato, however, as the noted reductions in germination were sporadic and no dose response was observed.

No reductions in germination were observed at any treatment rates for lettuce, oat and onion, with a 100% survival for all species at all rates of application.
At harvest, the height and dry weight of each surviving seedling from each replicate pot was measured.

No statistically significant reductions in height in comparison to the solvent control were identified at any treatment rate.

A significant reduction of 39% in dry weight was calculated for tomato at 1000 mg a.i./kg dry soil in comparison to the solvent control. No statistically significant reductions in dry weight were identified in any other species at any treatment rate.

No visible effects (e.g. phytotoxicity, wilting or leaf deformity) were observed at any treatment rate in any of the species.

Reported statistics and error estimates:

No statistically significant reductions in height in comparison to the solvent control were identified at any treatment rate.

A significant reduction of 39% in dry weight was calculated for tomato at 1000 mg a.i./kg dry soil in comparison to the solvent control. No statistically significant reductions in dry weight were identified in any other species at any treatment rate.

Validity criteria fulfilled:

yes

Conclusions:

The EC50 values for effects on germination, survival, height and dry weight for tomato, cabbage, carrot, lettuce, onion and oat were estimated to be greater than 1000 mg a.i./kg dry soil and the No Observed Effect Concentration (NOEC) for all six plant species was determined to be 1000 mg a.i./kg dry soil.

Executive summary:

There were no statistically significant effects on germination or survival of any plant species at any treatment rate of the test material tested. Germination and survival in the water control and solvent control were 100% for all species .

No statistically significant reductions in height in comparison to the solvent control were observed for cabbage, carrot, lettuce, tomato and oat.  A statistically significant reduction in the height of onion, (6%, p<0.05), was not considered to be biologically significant.  There were statistically significant reductions in the height of cabbage and onion in the water control in comparison to the solvent control.  

There were no statistically significant reductions in dry weight in treated plants when compared to either the solvent or water controls.  

Apart from the noted reductions in plant growth, no visible effects (e.g. phytotoxicity, wilting or leaf deformity) were observed at any treatment rate in any of the species.

The EC50 values for effects on germination, survival, height and dry weight for tomato, cabbage, carrot, lettuce, onion and oat were estimated to be greater than 1000 mg a.i./kg dry soil and the No Observed Effect Concentration (NOEC) for all six plant species was determined to be 1000 mg a.i./kg dry soil.

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

There were no statistically significant reductions in dry weight in treated plants when compared to either the solvent or water controls.  

Key value for chemical safety assessment

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

1 000 mg/kg soil dw