Diisodecyl azelate

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:

18 Nov - 16 Dec 2016

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:

July 2006

Deviations:

yes

Remarks:

Relative air humidity fell below 30 %. However, plants were watered enough and did not show any adverse effect. It is concluded that the deviations had no impact on the conduct or integrity of the study.

GLP compliance:

yes (incl. QA statement)

Remarks:

Hess. Ministerium für Umwelt, Klimaschutz, Landwirtschaft und Verbraucherschutz, Mainzer Str. 80, D-65189 Wiesbaden

Analytical monitoring:

no

Vehicle:

yes

Remarks:

Acetone

Details on preparation and application of test substrate:

- Method of mixing into soil: The test item was dissolved in acetone and spiked onto quartz sand which was mixed thoroughly into the soil after complete evaporation of the solvent.
- Controls: The control soil was mixed with the same amount of quartz sand that was neither treated with solvent nor with the test item. The solvent control soil was mixed with the same amount of quartz sand that was treated with the solvent but without the test item.
- Chemical name of vehicle: Acetone
- Evaporation of vehicle before use: yes

Species:

Allium cepa

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Onion
- Plant family: Amaryllidaceae
- Source of seed: Enza Zaden/Stuttgarter Riesen, Lot No. 4333216
- Storage: Untreated seeds were provided from commercial dealers and stored under cool and dry conditions in the dark.

Species:

Avena sativa

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: oat
- Plant family: Poaceae
- Source of seed: Nordsaat/ Canyon
- Storage: Untreated seeds were provided from commercial dealers and stored under cool and dry conditions in the dark.

Species:

Brassica napus

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: rape
- Plant family: Brassicaceae
- Source of seed: Feldsaaten/Akela
- Storage: Untreated seeds were provided from commercial dealers and stored under cool and dry conditions in the dark.

Species:

Cucumis sativus

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: cucumber
- Plant family: Cucurbitaceae
- Source of seed: Enza Zaden /Delikatess, Lot No.4291508
- Storage: Untreated seeds were provided from commercial dealers and stored under cool and dry conditions in the dark.

Species:

Pisum sativum

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: pea
- Plant family: Fabaceae
- Source of seed: Enza Zaden/ Rondo, 117024NN
- Storage: Untreated seeds were provided from commercial dealers and stored under cool and dry conditions in the dark.

Species:

other: Solanum lycopersicum

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: tomato
- Plant family: Solanaceae
- Source of seed: Enza Zaden/ Hellfrucht, Lot No.4317738
- Storage: Untreated seeds were provided from commercial dealers and stored under cool and dry conditions in the dark.

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:

21.0 °C (mean, 15.4 - 24.1°C, air conditioned test room for all plant species except Brassica napus) and 24.6 °C (mean, 21.8 - 26.5 °C, air conditioned test room for Brassica napus)

pH:

5.9 ± 0.6 (0.01 M CaCl2)

Moisture:

Rel.air humidity [%]: 42.1 (29.2 - 60.5, air conditioned test room for all plant species except Brassica napus) and 28.5 (15.8 - 49.9, air conditioned test room for Brassica napus)

Details on test conditions:

TEST SYSTEM
- Testing facility: E·C·T Oekotoxikologie GmbH, Flörsheim, Germany
- Test container: Common plant pots of polypropylene, diameter 11 cm, height 8.5 cm
- Amount of soil: 475 ± 10 g soil fresh weight per pot and placed in a separate polystyrene beaker (Kastelplast GmbH, Mainz, Germany) serving as water reservoir
- Method of seeding: The seeds were randomly picked and pressed into the soil at a uniform distance between seeds. The seeds had neither been dressed with fungicides nor imbibed with water.
- No. of seeds per container: 6 (Monocots) or 3 (Dicots)
- No. of plants (total number of seeds per species and treatment): 21 (B.napus, C.sativus, P. sativum, S.lycopersicum) or 24 (A.cepa, A.sativa) (see table 1 in section "Any other information on results incl tables")
- No. of replicates per treatment group: 4 (Monocots) 7 (dicots) pots per treatment
- No. of replicates per control: 4 (Monocots) and 7 (dicots) pots
- No. of replicates per vehicle control: 4 (Monocots) and 7 (dicots) pots

SOURCE AND PROPERTIES OF SUBSTRATE:
- Geographic location: Standard soil LUFA Type 2.3, from the Landwirtschaftliche Untersuchungs- und Forschungsanstalt (LUFA), D-67346 Speyer, Germany, sampled on 24 Oct 2016
- Pesticide use history at the collection site: LUFA soil Type 2.3 was collected from an uncultivated field at Offenbach, Rhineland-Palatinate, Germany, and sieved (≤2 mm). The field had neither received any organic fertilisers nor plant protection substances during the last four years before sampling. The soil was stored at ECT GmbH at ambient temperature until usage.
Soil texture (if natural soil):
- % sand: 59.6 ± 1.4
- % silt: 33.6 ± 0.5
- % clay: 6.8 ± 1.6
- Soil taxonomic classification: sandy loam
- Soil classification system: USDA
- Nitrogen: 0.08 ± 0.01%
- Organic carbon content: 0.67 ± 0.03%
- Maximum water holding capacity (in % dry weigth): 35.6 ± 1.4%
- CEC: 7.6 ± 0.8 meq/100 g

GROWTH CONDITIONS
- Photoperiod: 16 h light/ 8 h darkness
- Light source: SON-T-Agro high pressure metal halide lamps, Philips GmbH
- Light intensity and quality: 201 - 352 [μE m-2 s-1]
- Day/night temperatures: 15.5 - 26.5 °C
- Relative humidity: 15.8 - 60.5%
- Watering regime and schedules: Soils were watered by bottom watering via reservoirs which were filled regulary
- Volume applied: test solutions were applied at a volume of 15 mL, 25 mL or 40 mL to 63 g, 99 g or 162 g of quartz sand, respectively
- Interval of applications: once
- Method of application: stock solutions were mixed with sand, evaporated and mixed with soil

EFFECT PARAMETERS MEASURED: seedling emergence, seedling survival, visual appearance, determination of of shoot fresh weight. Visual appearance was checked after 7, 14 days and at test end. Shoot weight was determined at test end. Timepoint of all the other parameters are summarized within the table 1 in section "Any other information on results incl. tables"

- Phytotoxicity rating system: No phytotoxicity was observed in the controls

VEHICLE CONTROL PERFORMED: yes

TEST CONCENTRATIONS
- Spacing factor for test concentrations: ca. 2.7
Range finding study
- Results used to determine the conditions for the definitive study: The test concentrations were defined by the study director in consultation with the sponsor and are based on the results of a previously performed non-GLP range-finding test.

Nominal and measured concentrations:

Control, solvent control, 3.49, 9.41, 25.4, 68.6, 185 and 500 test item mg/kg soil dw

Reference substance (positive control):

no

Species:

Allium cepa

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

187.1 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Shoot fresh weight

Remarks on result:

other: Only the most sensitive parameter was reported all other endpoints are summarized within the table 4 in section "Any other information on results incl tables".

Species:

Allium cepa

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

68.6 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Shoot fresh weight

Remarks on result:

other: Only the most sensitive parameter was reported all other endpoints are summarized within the table 4 in section "Any other information on results incl tables".

Details on results:

SEEDLING EMERGENCE
- Percent seedling emergence: in control at least 70.8%. Allium cepa: significantly reduced at 500 mg/kg soil dry weight. None of the other test species showed significant effects up to and including 185 mg/kg soil dry weight (B. napus, S. lycopersicum) or 500 mg/kg soil dry weight (A. cepa, A. sativa, C. sativus, P. sativum), respectively.
- Percent survival: in controls at least 95.2%. No statistically significant effect up to and including 185 mg/kg soil dry weight (B. napus, S. lycopersicum) or 500 mg/kg soil dry weight (A. cepa, A. sativa, C. sativus, P. sativum) were observed, respectively.
- Abnormal seed development or visual appearance: no different visual appearance was visible compared to non-treated control soil and did not exhibit any visible test item related damages except for C. sativus which showed some dark discolorations of leaves when treated at 500 mg/kg soil dry weight.
- Seedling Shoot Fresh Weight: Shoot fresh weight was significantly reduced at test item concentrations of ≥185 mg/kg soil dry weight (A. cepa, B. napus, C. sativus and S. lycopersicum) and at ≥500 mg/kg soil dry weight (A. sativa). For P. sativum no effects on shoot fresh weight were observed up to 500 mg/kg soil dry weight.

Reported statistics and error estimates:

Statistical methods were applied to evaluate whether differences between test item treatments and solvent control were significant. Emergence and survival data were checked by the Fisher's exact binominal test with Bonferroni correction to determine the NOEC and LOEC. Significance level was alpha = 0.05, one sided greater. Probit Analysis was used to determine the effective concentrations EC25 and EC50 for the end point shoot fresh weight. Normal distribution and homogeneity of variances were checked by the Kolmogorov-Smirnov Test and Cochran’s test, respectively. NOEC and LOEC of shoot fresh weight were determined by applying either the Williams multiple sequential t-test (monotonous dose-response relationship) or Dunnett’s Multiple t-test (non-monotonous dose response relationship). In case of inhomogeneous variances Welch t-Test or Multiple sequentially-rejective U-test (non-parametric) were applied. Significance level was alpha = 0.05, one-sided smaller. Statistical evaluations were performed using the ToxRat Pro software Version 2.10 (ToxRat Solutions GmbH, 2010).

Table 1: Number of seeds introduced, number of emerged seeds, and number of survived seedlings in the untreated control pots.

Plant species	Seeds [No.] 1	Day 0 [d] 2	Emerged [No.] 3	Survived [No.] 4	Emerged [%]	Survived [%]
A. cepa	24	7	17	17	70.8	100.0
A. sativa	24	3	21	21	87.5	100.0
B. napus	21	3	18	18	85.7	100.0
C. sativus	21	4	20	20	95.2	100.0
P. sativum	21	4	21	21	100.0	100.0
S. lycopersicum	21	5	21	20	100.0	95.2

(1) Total number of seeds introduced; (2) day 0 of the test given as days after sowing; (3) emerged until day 7 (plants which emerged after day 7 were not considered); (4) survived until test end.

 

Table 2: Seedling emergence

Treatment code	C	SC	T1	T2	T3	T4	T5	T6
Test item [mg/kg soil dw]	0.0	0.0	3.49	9.41	25.4	68.6	185	500
	Number of seeds planted
A. cepa	24	24	---	24	24	24	24	24
A. sativa	24	24	---	24	24	24	24	24
B. napus	21	21	21	21	21	21	21	---
C. sativus	21	21	---	21	21	21	21	21
P. sativum	21	21	---	21	21	21	21	21
S. lycopersicum	21	21	21	21	21	21	21	---
	Number of emerged seeds per treatment on day 7*
A. cepa	17	16	---	19	19	19	16	1
A. sativa	21	23	---	23	22	21	22	24
B. napus	18	21	18	19	19	19	21	---
C. sativus	20	19	---	19	20	17	20	19
P. sativum	21	17	---	18	19	19	20	21
S. lycopersicum	21	19	21	20	20	21	20	---
	Relative number of emerged seeds [% of seeds sown]
A. cepa	70.8	66.7	---	79.2	79.2	79.2	66.7	4.2
A. sativa	87.5	95.8	---	95.8	91.7	87.5	91.7	100
B. napus	85.7	100	85.7	90.5	90.5	90.5	100	---
C. sativus	95.2	90.5	---	90.5	95.2	81.0	95.2	90.5
P. sativum	100	81.0	---	85.7	90.5	90.5	95.2	100
S. lycopersicum	100	90.5	100	95.2	95.2	100	95.2	---
	Mean % emergence as % of mean emergence of the solvent control
A. cepa	106	100	---	119	119	119	100	6.3
A. sativa	91.3	100	---	100	95.7	91.3	95.7	104
B. napus	85.7	100	85.7	90.5	90.5	90.5	100	---
C. sativus	105	100	---	100	105	89.5	105	100
P. sativum	123	100	---	106	112	112	118	123
S. lycopersicum	110	100	110	105	105	110	105	---

(---) = respective treatment not tested; * = post day 7 emergence not considered.

Table 3: Seedling survival

Treatment code C	SC	T1	T2	T3	T4	T5	T6
Test item [mg/kg soil dw]	0.0	0.0	3.49	9.41	25.4	68.6	185	500
	Number of emerged seeds per treatment on day 7*
A. cepa	17	16	---	19	19	19	16	1
A. sativa	21	23	---	23	22	21	22	24
B. napus	18	21	18	19	19	19	21	---
C. sativus	20	19	---	19	20	17	20	19
P. sativum	21	17	---	18	19	19	20	21
S. lycopersicum	21	19	21	20	20	21	20	---
	Number of live seedlings at test end
A. cepa	17	16	---	19	19	18	14	1
A. sativa	21	23	---	23	22	21	22	24
B. napus	18	21	18	19	19	19	21	---
C. sativus	20	19	---	19	20	17	20	19
P. sativum	21	17	---	18	19	19	19	21
S. lycopersicum	20	19	21	20	20	21	20	---
	Relative number of live seedlings at test end [% of emerged]
A. cepa	100	100	---	100	100	94.7	87.5	100
A. sativa	100	100	---	100	100	100	100	100
B. napus	100	100	100	100	100	100	100	---
C. sativus	100	100	---	100	100	100	100	100
P. sativum	100	100	---	100	100	100	95.0	100
S. lycopersicum	95.2	100	100	100	100	100	100	---
	Mean % survival as % of mean survival of the solvent control
A. cepa	100	100	---	100	100	94.7	87.5	100
A. sativa	100	100	---	100	100	100	100	100
B. napus	100	100	100	100	100	100	100	---
C. sativus	100	100	---	100	100	100	100	100
P. sativum	100	100	---	100	100	100	95.0	100
S. lycopersicum	95.2	100	100	100	100	100	100	---

(---) = respective treatment not tested; * = post day 7 emergence not considered.

Table 4: Summary of the EC25, EC50 (with 95% confidence intervals, CI), LOEC, and NOEC of the endpoints emergence, survival and shoot fresh weight, referring to nominal test item concentration [mg/kg soil dry weight].

Species	NOEC	LOEC	EC25	EC50
	Emergence
A. cepa	185	500	n.d.	n.d.
A. sativa	≥500	>500	n.d.	n.d.
B. napus	≥185	>185	n.d.	n.d.
C. sativus	≥500	>500	n.d.	n.d.
P. sativum	≥500	>500	n.d.	n.d.
S. lycopersicum	≥185	>185	n.d.	n.d.
	Survival
A. cepa	≥500	>500	n.d.	n.d.
A. sativa	≥500	>500	n.d.	n.d.
B. napus	≥185	>185	n.d.	n.d.
C. sativus	≥500	>500	n.d.	n.d.
P. sativum	≥500	>500	n.d.	n.d.
S. lycopersicum	≥185	>185	n.d.	n.d.
	Shoot fresh weight
A. cepa	68.6	185	99.7 (78.2-118.9)	187.1 (161.3-217.4)
A. sativa	185	500	398.3 (368.7-428.7)	n.d. (>500**)
B. napus	68.6	185	n.d.	n.d. (>185**)
C. sativus	68.6	185	261.8 (212.1-304.5)	n.d. (>500**)
P. sativum	≥500	>500	n.d.	n.d. (>500**)
S. lycopersicum	68.6	185	n.d.	n.d. (>185**)

n.d.: not determined; * Determined ECx values are not reasonable and thus not reported (expert judgement) ** Determined EC50 value is higher than the highest test concentration of 185 mg/kg soil dry weight and 500 mg/kg soil dry weight, respectively

Validity criteria fulfilled:

yes

Conclusions:

The effect of the test item Disodecyl azelate on the emergence and growth of six species of higher terrestrial plants was tested under laboratory conditions. The test item significantly reduced the emergence rate of one of the six test species (Allium cepa) at 500 mg/kg soil dry weight but had no significant effect on survival of seedlings in any of the six test species at any of the tested concentrations. The overall lowest NOEC and EC50 were 68.6 mg/kg soil dry weight and 187.1 mg/kg soil dry weight, respectively, and were observed with shoot fresh weight of Allium cepa.

Description of key information

NOEC (21 d): 68.6 mg /kg soil dry weight (Allium cepa, Shoot fresh weight, OECD 208, nominal)

Key value for chemical safety assessment

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

68.6 mg/kg soil dw

Additional information

One experimental study was available investigating the toxicity of the test item Disodecyl azelate (CAS 28472-97-1, ECT 2017) to terrestrial plants. The study was performed according to OECD 208 and GLP. The effect of the test item on the emergence and growth of six species of higher terrestrial plants was tested under laboratory conditions. The seeds of two monocotyledonous species, as well as four dicotyledonous species, were planted in a natural sandy loam soil immediately after test item application and left to grow under controlled conditions for up to 21 days following 50% emergence of the control plants. Five test item concentrations were tested with each species: 3.49, 9.41, 25.4, 68.6 and 185 mg/kg soil dry weight (B. napus, S. lycopersicum) and 9.41, 25.4, 68.6, 185.0 and 500 mg/kg soil dry weight (A. cepa, A. sativa, C. sativus, P. sativum). The test item was dissolved in acetone and spiked onto quartz sand which was mixed thoroughly into the soil after complete evaporation of the solvent. On day 7 and 14 after 50% emergence of control, seedlings were evaluated visually. At test end, seedlings were counted, evaluated visually, and harvested to determine shoot fresh weight. The validity criteria were fulfilled as seedling emergence in the control was ≥ 70% and seedling survival in the control was ≥ 90% for all six species. No phytotoxicity was observed in the controls. The test item significantly reduced the emergence rate of one of the six test species (Allium cepa) at 500 mg/kg soil dry weight but had no significant effect on survival of seedlings at any of the tested concentrations in any of the six test species. The overall lowest NOEC was 68.6 mg/kg soil dry weight based on shoot fresh weight of Allium cepa.