Tris(2-ethylhexyl) phosphate

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

Qualifier:

according to guideline

Guideline:

OECD Guideline 208 (Terrestrial Plants, Growth Test)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Samples:
Duplicate samples of approximately 20 mL from the homogenous stock solution and two samples of the matrix (acetone) as control solution were taken.
The concentration of the test item was determined in one sample of each duplicate.
Storage:
The samples were stored deep frozen (≤-20 °C) until analysis was performed. Afterwards the samples were again stored deep frozen (≤ -20 °C) and will be kept stored up to the date of the final report.

Standard Solutions used for Quantification
Stock Solution: The test item was dissolved with acetone to obtain a stock solution of approximately 1 g test item/L.
Standard Solutions: Aliquots of the stock solution were diluted with acetone to get standard solutions in the range from 100 to 750 mg test item/L.
Sample Preparation
Sample Preparation: An aliquot of each sample was diluted with acetone while solutions were shaken well.
Fortification Procedure: The test item was dissolved (stirred for 60 minutes) in acetone to get fortified samples of about 500 g test item/L. These solutions were diluted in acetone to obtain fortified samples of about 250 g test item/L.
Replicates: Five independent replicates per fortification level Two independent replicates of solvent control

Vehicle:

yes

Remarks:

acetone

Details on preparation and application of test substrate:

The test item was dissolved in acetone and mixed with fine quartz sand (allowed to evaporate overnight) before the test item treated sand was mixed into the soil. The amount of quartz sand depended on the water content of the used charge of soil. The amount of quartz sand was 66.9 g quartz sand per kg dry soil.
A stock solution of 114 g test item ad 250 mL acetone was prepared. For the following dilution series 40.0 mL out of the next higher concentration were added to 80.0 mL acetone.
Then adequate volumes of the acetone solutions were given to fine quartz sand and mixed with a laboratory mixer. The acetone was allowed to evaporate overnight out of the sand mixtures. The next day, all sand mixtures were given on adequate volumes of soil and each batch was mixed thoroughly for 5 minutes in a laboratory mixer.
The control was treated with the same amount of untreated sand per kg dry soil as the test item groups and acetone control.
The solvent control was treated with the same amount of acetone treated sand per kg dry soil as the test item groups.

Species:

Brassica napus

Plant group:

Dicotyledonae (dicots)

Species:

Glycine max (G. soja)

Plant group:

Dicotyledonae (dicots)

Species:

Lycopersicon esculentum

Plant group:

Dicotyledonae (dicots)

Species:

Cucumis sativus

Plant group:

Dicotyledonae (dicots)

Species:

Avena sativa

Plant group:

Monocotyledonae (monocots)

Species:

Allium cepa

Plant group:

Monocotyledonae (monocots)

Test type:

seedling emergence and seedling growth test

Study type:

laboratory study

Substrate type:

natural soil

Limit test:

no

Total exposure duration:

21 d

Test temperature:

15.3 - 28.4 °C

Moisture:

42 - 79 % humidity

Details on test conditions:

Test Design:
The test item was mixed into the soil before sowing. Only untreated seeds were used. The seeds were introduced manually into the soil. The exposure time was 14 or 21 days after 50% emergence in the control depending on the growth of the seedlings. For the untreated control the same amount of untreated quartz sand as in the test item treated groups was added to the soil. For the solvent treated control, the same amount of acetone treated quartz sand as in the test item treated groups was added to the soil.
Photoperiod: 16 hours light / 8 hours dark.
Mean light intensity during the day was 264 μE/m2/s (200 to 400 μE/m2/s).
4 to 10 pots each containing 2 to 5 seeds were tested for each treatment group. Each pot represented one replicate. 20 to 21 seeds per species and treatment group were tested. For a given test species, all seeds used in the test were from the same source and lot number.

Nominal and measured concentrations:

Nominal (Glycine max, Lycopersicon esculentum): 12.4, 37.0, 111, 333, 1000 mg/kg soil d.w.
Nominal (Brassica napus, Cucumis sativus, Avena sativa, Allium cepa): 1000 mg/kg soil d.w.

Species:

Brassica napus

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

1 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: fresh weight

Species:

Glycine max (G. soja)

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

1 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: fresh weight

Species:

Cucumis sativus

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

1 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: fresh weight

Species:

Avena sativa

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

1 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: fresh weight

Species:

Allium cepa

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

1 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: fresh weight

Species:

Lycopersicon esculentum

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

37 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: fresh weight

Species:

Lycopersicon esculentum

Duration:

14 d

Dose descriptor:

EC50

Effect conc.:

748 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: fresh weight

Reported statistics and error estimates:

Fresh weight data were tested for normal distribution and homogeneity of variance using Shapiro-Wilk’s test (α = 0.01) and the Levene’s test (α = 0.01). For Brassica napus, Cucumis sativus, Avena sativa and Allium cepa the Student t-test (pairwise comparison, one-sided smaller, α = 0.05) was used for comparing treatment group and pooled control.
For Glycine max Bonferroni-Holm U-test, α = 0.05 was used. For Solanum lycopersicum the analysis of contrasts revealed a linear trend, thus the Williams t-test (multiple comparison, one-sided smaller, α = 0.05) was used for comparing treatment groups and pooled control.
For Solanum lycopersicum a regression analysis was performed (Probit-analysis) to determine the EC10, EC20 and EC50 values.
The software used to perform the statistical analysis was ToxRat Professional, Version 3.3.0 ®ToxRat Solutions GmbH.

Validity criteria fulfilled:

yes

Remarks:

Emergence Rate of the Control Seeds >= 70%, Mean Survival of Emerged Control Seedlings: >= 90%, Growth and Morphology of the Control Seedlings:no visible phytotoxic effects and plants should exhibit only normal variation in growth and morphology

Conclusions:

Tris(2-ethylhexyl)phosphate was tested for effects on seedling emergence and seedling growth of six plant species out of six different plant families.
All plant species except Solanum lycopersicum showed a NOEC in terms of fresh weight of 1000 mg Tris(2-ethylhexyl)phosphate/kg soil dry weight. The most sensitive species in terms of fresh weight was Solanum lycopersicum with a NOEC of 37.0 mg Tris(2-ethylhexyl)phosphate/kg soil dry weight (EC50 748 mg Tris(2-ethylhexyl)phosphate/kg soil dry weight).
The emergence rate was not statistically significantly reduced for any species tested.
No statistically significant mortality was observed for any species tested.
Phytotoxic effects were growth reduction, for Glycine max stem deformations (2 observations) and necrosis. Phytotoxic symptoms remained low.

Executive summary:

Tris(2-ethylhexyl)phosphate was tested for effects on seedling emergence and seedling growth of six plant species out of six different plant families.

Tris(2-ethylhexyl)phosphate was mixed into the soil before sowing. Only untreated seeds were used. The seeds were introduced manually into the soil. Nominal concentration levels were 12.4, 37.0, 111, 333, 1000 mg/kg soil d.w. for Glycine max, Lycopersicon esculentum and 1000 mg/kg soil d.w. for Brassica napus, Cucumis sativus, Avena sativa, Allium cepa. The exposure time was 14 or 21 days after 50% emergence in the control depending on the growth of the seedlings. For the untreated control the same amount of untreated quartz sand as in the test item treated groups was added to the soil. For the solvent treated control, the same amount of acetone treated quartz sand as in the test item treated groups was added to the soil. 4 to 10 pots each containing 2 to 5 seeds were tested for each treatment group. Each pot represented one replicate. 20 to 21 seeds per species and treatment group were tested.

All plant species except Solanum lycopersicum showed a NOEC in terms of fresh weight of 1000 mg Tris(2-ethylhexyl)phosphate/kg soil dry weight. The most sensitive species in terms of fresh weight was Solanum lycopersicum with a NOEC of 37.0 mg Tris(2-ethylhexyl)phosphate/kg soil dry weight (EC50 748 mg Tris(2-ethylhexyl)phosphate/kg soil dry weight).

The emergence rate was not statistically significantly reduced for any species tested.

No statistically significant mortality was observed for any species tested.

Phytotoxic effects were growth reduction, for Glycine max stem deformations (2 observations) and necrosis. Phytotoxic symptoms remained low.

Description of key information

Tris(2-ethylhexyl)phosphate was tested for effects on seedling emergence and seedling growth of six plant species out of six different plant families.

Tris(2-ethylhexyl)phosphate was mixed into the soil before sowing. Only untreated seeds were used. The seeds were introduced manually into the soil. Nominal concentration levels were 12.4, 37.0, 111, 333, 1000 mg/kg soil d.w. for Glycine max, Lycopersicon esculentum and 1000 mg/kg soil d.w. for Brassica napus, Cucumis sativus, Avena sativa, Allium cepa. The exposure time was 14 or 21 days after 50% emergence in the control depending on the growth of the seedlings. For the untreated control the same amount of untreated quartz sand as in the test item treated groups was added to the soil. For the solvent treated control, the same amount of acetone treated quartz sand as in the test item treated groups was added to the soil. 4 to 10 pots each containing 2 to 5 seeds were tested for each treatment group. Each pot represented one replicate. 20 to 21 seeds per species and treatment group were tested.

All plant species except Solanum lycopersicum showed a NOEC in terms of fresh weight of 1000 mg Tris(2-ethylhexyl)phosphate/kg soil dry weight. The most sensitive species in terms of fresh weight was Solanum lycopersicum with a NOEC of 37.0 mg Tris(2-ethylhexyl)phosphate/kg soil dry weight (EC50 748 mg Tris(2-ethylhexyl)phosphate/kg soil dry weight).

Key value for chemical safety assessment

Short-term EC50 or LC50 for terrestrial plants:

748 mg/kg soil dw

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

37 mg/kg soil dw