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Toxicity to terrestrial plants

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Reference
Endpoint:
toxicity to terrestrial plants: short-term (with study design considered suitable for long-term assessment)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2020-08-24 - 2021-03-01 (experimental phase)
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:
adopted 19 July 2006
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
yes
Details on sampling:
Analytical Verification of Test Concentration
The measured test item concentration of the stock solution used to spike the quartz sand for the highest test concentration was 279.7 mg/mL corresponding to 105.5% of nominal (265 mg/mL).
Vehicle:
yes
Details on preparation and application of test substrate:
A quantity of 26.508 g of the test item was made up with acetone to a total volume of 100 mL in a volumetric flask. The resulting stock solution (SL) had a nominal test item concentration of 265.1 mg/mL and was stirred for more than 10 minutes to completely dissolve the test item. Aliquots of the stock solution were diluted with acetone. All test solutions were applied at a volume of 20 mL to 81 g of quartz sand. For the solvent control 162 g of quartz sand were spiked with 40 mL of the solvent without test item. The quartz sand for the control (162 g) was neither treated with solvent nor with the test item. After complete passive evaporation of the solvent at ambient conditions the spiked sand (or non-spiked sand for the control) was mixed thoroughly into the corresponding soil dry weight equivalent (control and solvent control) by the use of an electric stirrer equipped with a three helix stirrer rod for 3 minutes.
Species:
Allium cepa
Plant group:
Monocotyledonae (monocots)
Details on test organisms:
Common name: onion
Plant family: Amaryllidaceae
Cultivar: Stuttgarter Riesen,
Lot. No: 4367035,
Supplier: Enza Zaden Deutschland GmbH & Co. KG, Dannstadt-Schauernheim, Germany
Species:
Avena sativa
Plant group:
Monocotyledonae (monocots)
Details on test organisms:
Common name: oat
Plant family: Poaceae
Cultivar: Bio Sommerhafer
Lot No: 21257
Supplier: Sativa Rheingau AG
Species:
Brassica rapa
Plant group:
Dicotyledonae (dicots)
Details on test organisms:
Common name: turnip
Plant family: Brassicaceae
Cultivar: Namenia
Lot No: 252-0525-100116Z
Supplier: Bioland Mühlenbachhof, 49324 Melle, Germany.
Species:
Cucumis sativus
Plant group:
Dicotyledonae (dicots)
Details on test organisms:
Common name: cucumber
Plant family: Cucurbitaceae
Cultivar: Marketmore
Lot. No: 4382332
Supplier: Enza Zaden Deutschland GmbH & Co. KG, Dannstadt-Schauernheim, Germany
Species:
Pisum sativum
Plant group:
Dicotyledonae (dicots)
Details on test organisms:
Common name: pea
Plant family: Fabaceae
Cultivar: Ambrosia
Lot. No: 14520/19
Supplier: Demeter
Species:
other: Solanum lycopersicum
Plant group:
Dicotyledonae (dicots)
Details on test organisms:
Common name: tomato
Plant family: Solanacae
Cultivar: Hellfrucht
Lot. No: 7513050
Supplier: Enza Zaden Deutschland GmbH & Co. KG, Dannstadt-Schauernheim, Germany
Test type:
seedling emergence and seedling growth test
Study type:
laboratory study
Substrate type:
natural soil
Limit test:
no
Total exposure duration:
14 d
Test temperature:
Air Temperature mean: 23 °C (min.15.1 - max. 28.8 °C)
Moisture:
Rel. air humidity [%] mean: 38.3 (min.20.5* - max. 55.1)
*Relative air humidity in the test room fell below the value of 25% given in the study plan. This deviation, however, occurred only one day before the end of the test and lasted for 8 hours. The conditions during the test ensured appropriate growing conditions for the test species as confirmed by the normal and healthy growth of the control plants in this study (as well as in many earlier studies).
Details on test conditions:
Plant Species
The test systems comprised a total of six different species out of six families of higher terrestrial plants. These included two monocotyledonous and four dicotyledonous species. Untreated seeds were provided from commercial dealers and stored under cool and dry conditions in the dark.

Dose Levels and Replication
Five test item concentrations were tested against untreated soil. The test concentrations had been defined by the study director in consultation with the sponsor and were based on the results of a previously performed non-GLP range-finding test.
There were four replicates (pots) per treatment with 6 seeds per pot for the monocotyledonous and seven replicates (pots) per treatment with 3 seeds per pot for the dicotyledonous species. Hence, the total number of seeds per species and treatment was at least 24 and 21, respectively. The number of pots and the number of seeds per pot were the same for all treatments of a given test species.

Test Soil
Standard soil LUFA Type 2.3, a sandy loam, was purchased from the Landwirtschaftliche Untersuchungs- und Forschungsanstalt (LUFA), D-67346 Speyer, Germany. 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.

Test Containers
Common plant pots made of polypropylene (diameter 11 cm, height 8.5 cm) were used as test pots. Each pot was filled with 495±5 g soil fresh weight and placed in a separate polystyrene beaker (Kastelplast GmbH, Mainz, Germany) serving as water reservoir

Five test item concentrations were tested against untreated soil (Table 3). The test concentrations had been defined by the study director in consultation with the sponsor and were based on the results of a previously performed non-GLP range-finding test.
There were four replicates (pots) per treatment with 6 seeds per pot for the monocotyledonous and seven replicates (pots) per treatment with 3 seeds per pot for the dicotyledonous species. Hence, the total number of seeds per species and treatment was at least 24 and 21, respectively. The number of pots and the number of seeds per pot were the same for all treatments of a given test species.

Nominal and measured concentrations:
The measured test item concentration of the stock solution used to spike the quartz sand for the highest test concentration was 279.7 mg/mL corresponding to 105.5% of nominal (265 mg/mL).
Reference substance (positive control):
no
Key result
Species:
Pisum sativum
Duration:
14 d
Dose descriptor:
EC10
Effect conc.:
8.8 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth
Remarks:
shoot fresh weight
Key result
Species:
Allium cepa
Duration:
14 d
Dose descriptor:
EC50
Effect conc.:
41.9 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth
Remarks:
shoot fresh weight
Key result
Species:
other: Solanum lycopersicum
Duration:
14 d
Dose descriptor:
LOEC
Effect conc.:
18 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth
Remarks:
shoot fresh weight
Remarks on result:
other: no values suggested by the statistical program, therefore defined according to the definition of LOEC given in Annex 1 of the OECD test guideline number 211
Key result
Species:
other: Solanum lycopersicum
Duration:
14 d
Dose descriptor:
NOEC
Effect conc.:
6 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth
Remarks:
shoot resh weight
Remarks on result:
other: no values suggested by the statistical program, therefore defined according to the definition of NOEC given in Annex 1 of the OECD test guideline number 211
Species:
Allium cepa
Duration:
14 d
Dose descriptor:
LOEC
Effect conc.:
54 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: shoot fresh weight
Species:
Avena sativa
Duration:
14 d
Dose descriptor:
LOEC
Effect conc.:
216 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: shoot fresh weight
Species:
Brassica rapa
Duration:
14 d
Dose descriptor:
LOEC
Effect conc.:
54 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: shoot fresh weight
Species:
Cucumis sativus
Duration:
14 d
Dose descriptor:
LOEC
Effect conc.:
72 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: shoot fresh weight
Species:
Pisum sativum
Duration:
14 d
Dose descriptor:
LOEC
Effect conc.:
72 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: shoot fresh weight
Species:
Avena sativa
Duration:
14 d
Dose descriptor:
EC10
Effect conc.:
294.8 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
seedling emergence
Species:
Allium cepa
Duration:
14 d
Dose descriptor:
LC10
Effect conc.:
40.5 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
phytotoxicity
Remarks:
seedling survival
Species:
Brassica rapa
Duration:
14 d
Dose descriptor:
LC10
Effect conc.:
127.1 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
phytotoxicity
Remarks:
seedling survival
Species:
Avena sativa
Duration:
14 d
Dose descriptor:
LC50
Effect conc.:
117.2 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
phytotoxicity
Remarks:
seedling survival
Species:
Brassica rapa
Duration:
14 d
Dose descriptor:
LC50
Effect conc.:
174.6 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
phytotoxicity
Remarks:
seedling survival
Species:
Allium cepa
Duration:
14 d
Dose descriptor:
LOEC
Effect conc.:
162 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
phytotoxicity
Remarks:
seedling survival
Species:
Brassica rapa
Duration:
14 d
Dose descriptor:
LOEC
Effect conc.:
162 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
phytotoxicity
Remarks:
seedling survival
Species:
Cucumis sativus
Duration:
14 d
Dose descriptor:
LOEC
Effect conc.:
216 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
phytotoxicity
Remarks:
seedling survival
Species:
Pisum sativum
Duration:
14 d
Dose descriptor:
LOEC
Effect conc.:
> 648 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
phytotoxicity
Remarks:
seedling survival
Species:
other: Solanum lycopersicum
Duration:
14 d
Dose descriptor:
LOEC
Effect conc.:
> 162 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
phytotoxicity
Remarks:
seedling survival
Species:
Allium cepa
Duration:
14 d
Dose descriptor:
NOEC
Effect conc.:
54 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
phytotoxicity
Remarks:
seedling survial
Species:
Brassica rapa
Duration:
14 d
Dose descriptor:
NOEC
Effect conc.:
54 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
phytotoxicity
Remarks:
seedling survival
Species:
Cucumis sativus
Duration:
14 d
Dose descriptor:
NOEC
Effect conc.:
72 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
phytotoxicity
Remarks:
seedling survival
Species:
Pisum sativum
Duration:
14 d
Dose descriptor:
NOEC
Effect conc.:
>= 648 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
phytotoxicity
Remarks:
seedling survival
Species:
other: Solanum lycopersicum
Duration:
14 d
Dose descriptor:
NOEC
Effect conc.:
>= 162 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
phytotoxicity
Remarks:
seedling survival
Species:
Allium cepa
Duration:
14 d
Dose descriptor:
EC10
Effect conc.:
13.2 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth
Remarks:
shoot fresh weight
Species:
Avena sativa
Duration:
14 d
Dose descriptor:
EC10
Effect conc.:
55.8 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth
Remarks:
shoot fresh weight
Species:
Brassica rapa
Duration:
14 d
Dose descriptor:
EC10
Effect conc.:
11.5 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth
Remarks:
shoot fresh weight
Species:
Cucumis sativus
Duration:
14 d
Dose descriptor:
EC10
Effect conc.:
33.8 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth
Remarks:
shoot fresh weight
Species:
other: Solanum lycopersicum
Duration:
14 d
Dose descriptor:
EC10
Effect conc.:
12.2 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth
Remarks:
shoot fresh weight
Species:
Avena sativa
Duration:
14 d
Dose descriptor:
EC50
Effect conc.:
262.6 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth
Remarks:
shoot fresh weight
Species:
Brassica rapa
Duration:
14 d
Dose descriptor:
EC50
Effect conc.:
43.2 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth
Remarks:
shoot fresh weight
Species:
Cucumis sativus
Duration:
14 d
Dose descriptor:
EC50
Effect conc.:
89.1 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth
Remarks:
shoot fresh weight
Species:
Pisum sativum
Duration:
14 d
Dose descriptor:
EC50
Effect conc.:
201.5 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth
Remarks:
shoot fresh weight
Species:
other: Solanum lycopersicum
Duration:
14 d
Dose descriptor:
EC50
Effect conc.:
50.8 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth
Remarks:
shoot fresh weight
Species:
Allium cepa
Duration:
14 d
Dose descriptor:
NOEC
Effect conc.:
18 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth
Remarks:
shoot fresh weight
Species:
Avena sativa
Duration:
14 d
Dose descriptor:
NOEC
Effect conc.:
72 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth
Remarks:
shoot fresh weight
Species:
Brassica rapa
Duration:
14 d
Dose descriptor:
NOEC
Effect conc.:
18 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth
Remarks:
shoot fresh weight
Species:
Cucumis sativus
Duration:
14 d
Dose descriptor:
NOEC
Effect conc.:
24 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth
Remarks:
shoot fresh weight
Species:
Pisum sativum
Duration:
14 d
Dose descriptor:
NOEC
Effect conc.:
24 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth
Remarks:
shoot fresh weight
Results with reference substance (positive control):
The test guideline does not recommend the testing of a reference substance. Therefore, the test was performed without a reference item.
Reported statistics and error estimates:
Number of emerged and number of survived seedlings as well as shoot fresh weight at the end of the test was considered for statistical data analysis. Statistical methods were applied to evaluate whether differences between seedlings emerged and grown test item treated soils and control soils were significant. Since no statistical difference was found between seedlings emerged and grown in control soil and solvent control soil the two controls were pooled.
Arithmetic means for each pot were calculated from the single plants within a pot. Since each pot constituted a replicate, the mean values were used for statistical analysis. Emergence and survival data were checked by the Chi2 2x2 Table Test with Bonferroni correction, Step-down Cochran-Armitage Test Procedure or in case of a non-monotone dose response with the Fisher's exact binominal test with Bonferroni correction to determine the NOEC and LOEC. Significance level was alpha = 0.05, one sided greater . The 3-Parameter normal cumulative distribution function was used to determine the effective concentrations EC10 and EC50 for the end point shoot fresh weight. Normal distribution and homogeneity of variances were checked by the Shapiro-wilk’s test and F-test or Levene’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). In case of inhomogeneous variances Welsh t-Test was applied. Significance level was alpha = 0.05, one-sided smaller. In case the normal distribution was found to be poor, the non-parametric step-down Jonckheere-Terpstra test procedure was applied.Statistical evaluations were performed using the ToxRat Pro software Version 3.30. (ToxRat Solutions GmbH, 2010).

Summary of the EC10, EC50 (with lower and upper 95% confidence intervals, CI), LOEC, and NOEC of the endpoints emergence, survival and shoot fresh weight. All data refer to nominal test item concentration [mg/kg soil dry weight].

 End point A. cepa  A. sativa  B. rapa  C. sativus  P. sativum  S. lycopersicum
 Emergence            
 EC10  n.d.  294.8  n.d.  n.d.  n.d.  n.d.
 lower CI  n.d.  84.2  n.d.  n.d.  n.d.  n.d.
 upper CI  n.d.  1717.7  n.d.  n.d.  n.d. n.d.
 EC50  n.d.  n.d.  n.d.  n.d.  n.d. n.d.
 LOEC  > 162  > 648  > 162
  > 648   > 648   > 648 
 NOEC  ≥162  ≥648  ≥162   ≥648  ≥648  ≥648 
 Survival            
 LC10  40.5  n.d.  127.1  n.d.  n.d.  n.d.
 lower CI  16.2  n.d.  n.d.  n.d.  n.d.  n.d.
 upper CI  60.8  n.d.  n.d.  n.d.  n.d.  n.d.
 LC50  117.2  n.d.  174.6  n.d.  n.d.  n.d.
 lower CI  79.3  n.d.  n.d.  n.d.  n.d.  n.d.
 upper CI  246.8  n.d.  n.d.  n.d.  n.d.  n.d.
 LOEC  162  n.d.  162  216  >648  >162
 NOEC  54.0  n.d.  54.0  72.0  ≥648  ≥162
 Shoot fresh weight            
 EC10  13.2  55.8  11.5  33.8  8.8  12.2
 lower CI  5.9  22.2  4.0  19.2  2.1  6.1
 upper CI  29.5  140.1  32.7  59.4  37.5  24.3
 EC50  41.9  262.6  43.2  89.1  201.5  50.8
 lower CI  16.1  86.4  12.2  44.6  31.4  22.0
 upper CI  106.7  773.6  149.3  174.7  1211.3  115.0
 LOEC  54.0  216  54.0  72.0  72.0  18.0#
NOEC  18.0  72.0  18.0  24.0  24.0  6.0#

n.d.: not determined / calculation not feasible (e.g. no dose-response relationship); # = no values suggested by the statistical program, therefore defined according to the definition of LOEC and NOEC given in Annex 1 of the OECD test guideline number 211.

Number of seeds introduced, number of emerged seeds, and number of survived seedlings in the control pots and solvent control pots.

                     Plant species
 A. cepa  A. sativa  B. rapa  C. sativus  P. sativum  S. lycopersicum
 Control            
No. of seeds1  24  24  21  21  21  21
 Day 02  7  4  4  4  5  5

 Number of emerged3

 18  23  17  19  17  21
 Number of survived4  17  23  17  19  17  21
 Per cent emerged  75.0  95.8  81.0  90.5  81.0  100.0
 Per cent survived  94.4  100.0  100.0  100.0  100.0  100.0
 Solvent Control            
  No. of seeds1  24  24  21  21  21  21
  Day 02  4  4  4  5  5

 Number of emerged3

 16

 23

 17

 15

 19

 18

  Number of survived4 16   23  16  15  18  18
 Per cent emerged  66.7  95.8  81.0  71.4  90.5  85.7
 Per cent survived  100.0  100.0  94.1  100.0  94.7  100.0

(1) Total number of seeds introduced; (2) day 0 of the test given as days after sowing; (3) emerged until test end; (4) survived until test end.

Visual Appearance

On day 7, day 14 and at the end of the study, the number of seedlings was counted and evaluated according to a 6-point scoring system with the categories shown below (Table 6). The six categories were chosen to facilitate and standardise the description of the visual appearance of the plants.

The allocation to a certain category does not necessarily mean that the observed phenomenon is an effect; especially categories 2 and 3 may be the expression of the normal variability of growth and morphology of the plant.

Scoring scheme for the visual evaluation of the test species.

Category              Evaluation               Description

1                      Healthy                    Plant with normal growth, without damages apart from what is within the normal range of variability (e.g. wilted cotyledons are no damage).

2                      Slightly damaged      Chlorotic and/or necrotic leaves (less than ¼ of the plant).

3                      Slightly damaged      Single wilted leaves (less than ¼ of the plant)

4                      Severely damaged    Chlorotic and/or necrotic and/or wilted leaves (more than ¼ of the plant).

5                      Severely damaged    Plant with developmental abnormalities.

6                      Dead                       All above-ground parts of the plant are wilted.

Validity criteria fulfilled:
yes
Conclusions:
The effect of the test item Ditolyl ether on the emergence and growth of six species of higher terrestrial plants was tested under laboratory conditions.
The lowest values for the end points EC10, EC50, LOEC and NOEC were observed with shoot fresh weight of the test species Allium cepa, Pisum sativum and Solanum lycopersicum. The values were as follows:
EC10 = 8.8 mg/kg soil dry weight (Pisum sativum)
EC50 = 41.9 mg/kg soil dry weight (Allium cepa)
LOEC = 18.0 mg/kg soil dry weight (Solanum lycopersicum)
NOEC = 6.0 mg/kg soil dry weight (Solanum lycopersicum)
Executive summary:

The effect of the test item Ditolyl ether on the emergence and growth of six species of higher terrestrial plants was tested accordig to OECD Guideline for the Testing of Chemicals No. 208; Terrestrial Plant Test: Seedling Emergence and Seedling Growth Test, adopted 19 July 2006.

Seeds of two monocotyledonous species, Allium cepa (onion) and Avena sativa (oat), as well as four dicotyledonous species, Brassica rapa (turnip), Cucumis sativus (cucumber), Pisum sativum (pea) and Solanum lycopersicum (tomato) were planted in a natural sandy loam soil (standard soil LUFA Sp 2.3) immediately after test item application and left to grow under controlled conditions for 14 days following 50 % emergence of the control plants. Test item concentrations ranged from 2.0 to 162 mg/kg soil dry weight for A. cepa and B. rapa and S. lycopersicum and from 8.0 to 648 mg/kg soil dw for A. sativa, P. sativum and C. sativus.

The test item was diluted in acetone to prepare a stock solution and dilutions thereof to spike quartz sand which was mixed into the test soils after complete evaporation of the solvent. The concentration of sand added to the soil was 1% (i.e. 10 g/kg soil). The solvent control soil was mixed with sand spiked with the solvent only and the control soil received non-spiked sand.

Soils were supplied with water and a nutrient solution as needed by bottom watering. The test was performed in a growth chamber equipped with artificial lighting (213 µE m-2 s-1, for 16 hours per day) and air conditioning (mean air temperature and mean relative air humidity were 23.0°C and 38.3%, respectively). The pots were placed randomly at the beginning of the test and were re-arranged at minimum weekly intervals. Day 0 was defined as the day on which at least 50% of the seeds had emerged in the control soil. Seedlings were counted and evaluated visually on day 7 and at the end of the test (day 14). Harvest of seedlings to determine shoot fresh weight, the number of live and dead seedlings as well as a visual examination of the seedlings was performed on day 14.

Emergence and Survival

The test item had no statistically significant effect on emergence except for Avena sativa for which an EC10 of 294.8 mg/kg soil dry weight was determined.

An effect on survival was seen with Allium cepa with LC10 (40.5 mg/kg soil dw), LC50 (117.2 mg/kg soil dw), LOEC (162 mg/kg soil dw) and NOEC (54.0 mg/kg soil dw). An EC10 was further determined with Brasica rapa (127.1 mg/kg soil dw). No statistically significant effect on survival cold be observed in any of the other four test species.

Shoot fresh weight

Shoot fresh weight was statistically significantly reduced at test item concentrations of ≥18.0 mg/kg soil dry weight in S. lycopersicum, ≥54.0 mg/kg soil dw in B. rapa, and A. cepa, ≥72.0 mg/kg soil dw in C. sativus and P. sativum, and ≥216 mg/kg soil dw in A. sativa.

The lowest values for the end points EC10, EC50, LOEC and NOEC were observed with shoot

fresh weight of the test species Allium cepa, Pisum sativum and Solanum lycopersicum. The

values were as follows:

EC10 = 8.8 mg/kg soil dry weight (Pisum sativum)

EC50 = 41.9 mg/kg soil dry weight (Allium cepa)

LOEC = 18.0 mg/kg soil dry weight (Solanum lycopersicum)

NOEC = 6.0 mg/kg soil dry weight (Solanum lycopersicum)

Description of key information

The effect of the test item Ditolyl ether on the emergence and growth of six species of higher terrestrial plants was tested accordig to OECD Guideline for the Testing of Chemicals No. 208; Terrestrial Plant Test: Seedling Emergence and Seedling Growth Test. The test item had no statistically significant effect on emergence except for Avena sativa for which an EC10 of 294.8 mg/kg soil dry weight could be determined.

An effect on survival was seen with Allium cepa for which an LC10, LC50, LOEC and NOEC could be determined and with Brassica rapa for which an LC10 could be determined. No statistically significant effect on survival could be observed in any of the other test species.

Shoot fresh weight was statistically significantly reduced at test item concentrations of ≥18.0 mg/kg soil dry weight in S. lycopersicum, ≥54.0 mg/kg soil dw in B. rapa, and A. cepa, ≥72.0 mg/kg soil dw in C. sativus and P. sativum, and ≥216 mg/kg soil dw in A. sativa.

The lowest values for the end points EC10, EC50, LOEC and NOEC were

observed with shoot fresh weight of the test species Allium cepa, Pisum

sativum and Solanum lycopersicum. The values were as follows:

EC10 = 8.8 mg/kg soil dry weight (Pisum sativum)

EC50 = 41.9 mg/kg soil dry weight (Allium cepa)

LOEC = 18.0 mg/kg soil dry weight (Solanum lycopersicum)

NOEC = 6.0 mg/kg soil dry weight (Solanum lycopersicum)

Key value for chemical safety assessment

Long-term EC10, LC10 or NOEC for terrestrial plants:
6 mg/kg soil dw

Additional information

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