Tris(2,4-ditert-butylphenyl) phosphite

Toxicity to terrestrial plants

Link to relevant study record(s)

Reference

Endpoint:

toxicity to terrestrial plants: long-term

Remarks:

Although the test does not cover chronic effects or effects on reproduction, it covers a sensitive stage in the life-cycle of a plant and data obtained form this study are generally used as estimate of chronic toxicity.

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)

Version / remarks:

(2006)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Details on preparation and application of test substrate:

- Test substrate: A 2:1 mixture of natural soil LUFA 2.2 (batch number: Test period A: Sp2.23115; Test period B: Sp2.20516) and quartz sand (12a) was used. Grain size: ≤2 mm; Carbon content: A: 1.0 %; B : 0.59 %; pH-value: A: 6.08 ± 0.02; B: 6.26 ± 0.04.- Origin: Landwirtschaftliche Untersuchungs- und Forschungsanstalt Speyer (LUFA), Obere Langgasse 40, 67346 Speyer, Germany. Dörentrup Quarz GmbH Co. KG, An der Sandgrube 1, 31089 Duingen, Germany

Species:

Avena sativa

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: oat; Flämingsgold- Origin: KWS LOCHOW GMBH, Ferdinand-von-Lochow-Strafe 5, 29303 Bergen, Germany

Species:

Allium cepa

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: onion; Exhibition- Origin: HILD SAMEN GMBH, Postfach 1161, 71666 Marbach, Germany

Species:

Beta vulgaris

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: sugar beet; Capella- Origin: KWS SAAT AG / KWS MAIS GMBH. Grimsehlstrage 31, 37574 Einbeck, Germany

Species:

Brassica napus

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: rape; Sherlock- Origin: KWS SAAT AG / KWS MAIS GMBH. Grimsehlstrage 31, 37574 Einbeck, Germany

Species:

Lactuca sativa

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: lettuce; Mafalda- Origin: HILD SAMEN GMBH, Postfach 1161, 71666 Marbach, Germany

Species:

Glycine max (G. soja)

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: soybean; Merlin- Origin: SAATBAU LINZ., A-4021 Linz, Schimmerstralle 19, P.O.B. 317

Test type:

seedling emergence and seedling growth test

Study type:

laboratory study

Substrate type:

natural soil

Limit test:

no

Total exposure duration:

21 d

Remarks:

Two test periods: A (2016-02-19 - 2016-03-11): oats, onion (prolonged until 2016-03-18), sugar beet, lettuce, soybean; B (2016-04-29 - 2016-05-20): rape. Exposure lasted for 14 to 21 days after 50 % emergence of the seedlings in the control group.

Test temperature:

- Nominal: 22 ± 10 °C- Actual A: 11 - 22 °C- Actual B: 16 - 23 °C

pH:

- A: 6.08 ± 0.02- B: 6.26 ± 0.04.

Moisture:

Adjusted to a moisture of 50 % of the maximum water holding capacity (WHC).

Details on test conditions:

- Number of replicates: 8 replicates per test concentration and control tested in a randomised block design- Number of seeds: 5 seeds per test container (soybean: 3 seeds)- Test container: Non-porous plastic containers (standard flower pots) with a diameter of ca. 12 cm were used. The pots were labelled with the study number and all necessary additional information to ensure unique identification.- Test substance application: Test item treatments (and control) were applied once at the beginning of the study. Due to large soil amounts per concentration, several batches were prepared per concentration and applied separately.- Application technique: The respective test item amounts were weighed out for each test item concentration and blended thoroughly with quartz sand (1 % of the entire soli amount per concentration). Afterwards the test item - quartz sand mixture and an appropriate amount of demineralised water were added to the soil. Subsequently, the soil was mixed carefully with a mixer (2 to 3 min) to ensure a homogeneous distribution. The treated soil was transferred to the test container.- Sowing: Test containers were filled each with the same amount of treated soil and seeding holes were made with a seedling pistil. One seed was given into each hole and covered with soil. During cultivation the test containers were bottom watered and fertilized as necessary.- Room: The test was conducted in a climatic hall. The test conditions approximated those conditions necessary for normal growth or typical environmental conditions for the species and varieties tested.- Photoperiod: 16h- Illumination: A: 4756 ± 404 lux; B: 4697 ± 467 lux- Relative humidity: A: 53 - 99%; B: 46 - 93%- Watering / fertilisation: Bottom watering of the test containers, including fertilizer as necessary.- Fertilizer: HAKAPHOS® SOFT SPEZIAL 16+8+22(+3) (origin: Griines Landhaus, St. Godehard-Str. 23, 31139 Hildesheim, Germany). For watering a 0.05 promile solution was used.EFFECT PARAMETERS MEASUREDDuring the 21 - 28 day observation period (from day of application) the plants were observed every 7 days for number of emerged seedlings, number of dead plants and visual phytotoxic effects. The rating of the treated plants was done in relation to the untreated control plants. Observations included all variations, either inhibitory or stimulatory, between the treated replicates and the untreated controls. Such variations may be phytotoxic symptoms (e.g. chlorosis, necrosis, wilting), effects of growth and development races. At the end of the study the shoot heights (in cm) and the shoot fresh weights of the shoots (in g) were measured additionally, directly after cutting the plants at the soil surface. The shoot height was measured per plant. Average mean values per replicate were calculated. The shoot fresh weight was determined for all plants from the same pot and considered as one replicate.PHYSICAL CHEMICAL PARAMETERS MEASUREDThe room temperature and relative humidity were recorded continuously throughout the test with a thermos-hygrograph. The illumination was determined at the start of the experiment.CHRONOLOGICAL TEST DESCRIPTION- Day -1 / -2: Determination of the WHC and the dry weight of the soil- Day 0 (Experimental starting): Application and sowing as specified above - Every working day: The test containers were bottom watered and fertilised as needed.- Day 7, 14, 21, 28: The replicates were observed for visual phytotoxic effects, number of emerged seedlings and number of dead plants.- Test end (day 21 / 28): Final shoot heights and shoot fresh weight measurements were done.

Nominal and measured concentrations:

- Nominal concentrations - oat, onion, lettuce: 0 (control), 12.3, 37.0, 111, 333 and 1000 mg/kg d.w.- Nominal concentrations - sugar beet, soybean: 0 (control) and 1000 mg/kg d.w.- Nominal concentrations - rape: 0 (control), 500 and 1000 mg/kg d.w.All nominal concentrations are based on a range-finding test

Reference substance (positive control):

no

Remarks:

No reference item is recommended for this test according to the test guideline (OECD 208).

Key result

Species:

other: all 6 plant species tested

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: shoot height, shoot fresh weight, number of emerged seedlings

Details on results:

No significant test item related phytotoxic effects and mortality occurred during the test period for all tested plant species.

Reported statistics and error estimates:

NOEC / LOECOne Way Analysis of Variance (ANOVA) was carried out for the determination of statistically significant differences compared to control replicates. When running a One Way Analysis of Variance, a Normality test and an Equal Variance test were done first. P-values for both, Normality and Equal Variance test, are 0.05. The alpha-value for ANOVA (acceptable probability of incorrectly conciuding that there is a difference) is = 0.05. For the shoot height of the plant species soybean and the emergence of the plant species oats, sugar beet, rape and soybean the Normality test failed. For the emergence of the plant species lettuce the Equal Variance test failed. The failure has no influence on the robustness of the study. It is only a tooi for deciding whether to reject the null hypothesis (P≤alpha).EC VALUESThe determined effects of shoot height, shoot fresh weight and number of emerged seedlings were < 25 %. Therefore, calculations of EC-values were not carried out.

Validity criteria fulfilled:

yes

Description of key information

The toxicity to terrestrial plants was determined in a study according to OECD guideline No 208 and in compliance with GLP criteria (BASF, 2016). In this study, 6 plant species were examined for visual phytotoxic effects and mortality. Oats, onions and lettuce were exposed to test substance concentrations of 0 (control), 12.3, 37.0, 111, 333 and 1000 mg/kg d.w. No test substance analysis was performed. Sugar beet and soybean were exposed to test substance concentrations of 0 (control) and 1000 mg/kg d.w. and finally rape was exposed to test substance concentrations of 0 (control), 500 and 1000 mg/kg d.w. All test concentrations were based on a preliminary range-finding test. The test item was incorporated into the soil in which the seeds were sown afterwards. The test containers were bottom watered with nutrient solution as needed. Potential toxic effects of the test item were assessed on day 7, 14 and 21 by visual observations (number of emerged seedlings and phytotoxic effects) and at test end by shoot height and shoot fresh weight determination. For onion the rate of emergence of the control plants reached >50 % within 14 days and therefore, the test with onion was prolonged until 28 days. No significant test item related phytotoxic effects and mortality occurred during the test period for all tested plant species. No EC50 values could therefore be determined. The NOEC was determined at ≥1000 mg/kg d.w. for shoot height, shoot fresh weight and number of emerged seedlings in all 6 plant species tested. Although the test does not cover chronic effects or effects on reproduction, it covers a sensitive stage in the life-cycle of a plant and data obtained from this study are generally used as estimate of chronic toxicity. Therefore, a 21 -d NOEC of 1000 mg/kg d.w. is used for assessment.

Key value for chemical safety assessment

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

1 000 mg/kg soil dw