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Toxicity to terrestrial plants

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Reference
Endpoint:
toxicity to terrestrial plants: long-term
Type of information:
experimental study
Adequacy of study:
key study
Study period:
July 31, 2015 to December 8, 2015
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Valid study conducted according to established protocol
Qualifier:
according to guideline
Guideline:
OECD Guideline 208 (Terrestrial Plants Test: Seedling Emergence and Seedling Growth Test)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
yes
Details on sampling:
A primary stock solution of the test substance was prepared by bringing 185.9 g of the test substance to a final volume of 2000 mL with THF, and mixing by swirling, inversion and stirring. The resulting stock solution was described as a translucent, pale beige liquid. Aliquots of 500, 250, 125 and 62.5 mL from the primary stock were each diluted to a final volume of 1000 mL with THF to prepare secondary stocks. Solvent and negative control stocks were prepared and consisted of THF and well water purified by reverse-osmosis, respectively. Triplicate samples were collected from the highest test concentrations while single samples were collected from the remaining treatment levels, solvent control and negative control. Analytical samples were stored refrigerated upon collection.
Vehicle:
no
Details on preparation and application of test substrate:
Test soils were prepared by adding 990 mL of each stock solution to 100 kg of bulk soil and mixing. Test soils were mixed in a soil mixer for a total of approximately 20 minutes, turned by hand after the first 10 minutes. The negative control soil was mixed first, then the solvent control and the test levels in order of increasing test concentration to avoid cross contamination of the test material. The target amounts of test substance used were based on an estimated soil moisture content of 8%. Therefore, 100 kg of soil was estimated to contain 92 kg soil dry weight. Soil moisture samples were collected on the day of soil preparation, and the actual soil moisture content was determined to be 5.82%.
Species:
Allium cepa
Plant group:
Monocotyledonae (monocots)
Details on test organisms:
Allium cepa (onion), Yellow Granex, Family Liliaceae. Source: Park Seed Co., Greenwood, SC USA
Species:
Avena sativa
Plant group:
Monocotyledonae (monocots)
Details on test organisms:
Avena sativa (oat), Saber, Family Poaceae. Source: Powell Seeds, Converse, IN USA
Species:
Beta vulgaris
Plant group:
Dicotyledonae (dicots)
Details on test organisms:
Beta vulgaris (sugarbeet), (no variety name provided), Family Chenopodiaceae. Source: Sustainable Seed Co., Covelo, CA USA
Species:
Brassica napus
Plant group:
Dicotyledonae (dicots)
Details on test organisms:
Brassica napus (oilseed rape), Dwarf Essex Rape, Family Brassicaceae. Source: Johnny’s Selected Seeds, Winslow, ME USA
Species:
Cucumis sativus
Plant group:
Dicotyledonae (dicots)
Details on test organisms:
Cucumis sativus (cucumber), Tendergreen Burpless, Family Cucurbitaceae. Source: The Meyer Seed Co., Baltimore, MD USA
Species:
Glycine max (G. soja)
Plant group:
Dicotyledonae (dicots)
Details on test organisms:
Glycine max (soybean), Viking 2265, Family Fabaceae. Source: Johnny’s Selected Seeds, Winslow, ME USA
Test type:
seedling emergence toxicity test
Study type:
laboratory study
Substrate type:
natural soil
Limit test:
no
Total exposure duration:
21 d
Test temperature:
The temperature within the greenhouse was controlled with a Wadsworth MicroStep S/A Environmental Control System. Mean temperature over the course of the study was 22.86 degrees Celsius as measured with a Campbell CR-10 datalogger.
pH:
Test soil pH was measured to be 6.7.
Moisture:
Soil moisture samples were collected on the day of soil preparation, and the actual soil moisture content was determined to be 5.82%.
Nominal and measured concentrations:
Measured soil concentrations (mg/kg) [Nominal concentrations in brackets]:
0 [0]
0 [0]
58.5 [62.5]
120 [125]
237 [250]
500 [500]
962 [1000]
Reference substance (positive control):
no
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: All parameters studied
Species:
Allium cepa
Duration:
21 d
Dose descriptor:
EC10
Effect conc.:
> 1 000 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: All parameters studied
Key result
Species:
Allium cepa
Duration:
21 d
Dose descriptor:
other: EC20
Effect conc.:
> 1 000 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: All parameters studied
Species:
Avena sativa
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
250 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: dry weight
Species:
Avena sativa
Duration:
21 d
Dose descriptor:
EC10
Effect conc.:
148 mg/kg soil dw
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
other: dry weight
Key result
Species:
Avena sativa
Duration:
21 d
Dose descriptor:
other: EC20
Effect conc.:
> 1 000 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: All parameters studied
Species:
Beta vulgaris
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
250 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
seedling emergence
Species:
Beta vulgaris
Duration:
21 d
Dose descriptor:
EC10
Effect conc.:
67.7 mg/kg soil dw
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
seedling emergence
Key result
Species:
Beta vulgaris
Duration:
21 d
Dose descriptor:
other: EC20
Effect conc.:
> 1 000 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
All parameters studied
Basis for effect:
other: All parameters studied.
Species:
Brassica napus
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
62.5 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: dry weight
Species:
Brassica napus
Duration:
21 d
Dose descriptor:
EC10
Effect conc.:
2.14 mg/kg soil dw
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
other: dry weight
Key result
Species:
Brassica napus
Duration:
21 d
Dose descriptor:
other: EC20
Effect conc.:
> 1 000 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: All parameters studied
Species:
Cucumis sativus
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
62.5 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: height
Species:
Cucumis sativus
Duration:
21 d
Dose descriptor:
EC10
Effect conc.:
23.4 mg/kg soil dw
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
other: height
Key result
Species:
Cucumis sativus
Duration:
21 d
Dose descriptor:
other: EC20
Effect conc.:
> 1 000 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: All parameters studied
Species:
Glycine max (G. soja)
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
500 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: height
Species:
Glycine max (G. soja)
Duration:
21 d
Dose descriptor:
EC10
Effect conc.:
> 1 000 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: All parameters studied
Key result
Species:
Glycine max (G. soja)
Duration:
21 d
Dose descriptor:
other: EC20
Effect conc.:
> 1 000 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: All parameters studied
Details on results:
Mean height and dry weight of the negative and solvent controls for Allium cepa were significantly different. The treatment group means for height and dry weight were therefore compared to the solvent control means. This was considered a more conservative comparison because the solvent control mean height and dry weight were greater than the corresponding negative control means. The A. cepa negative and solvent control data for emergence and survival, as well as all parameters of the remaining species, were pooled since no significant differences were detected.

There were statistically-significant reductions in mean emergence of B. vulgaris in the 500 and 1000 mg/kg groups. The reductions were not dose-responsive, and there were no accompanying reductions in survival, height, dry weight or condition of the seedlings. However, due to the significant differences observed the NOEC for B. vulgaris emergence was determined to be 250 mg/kg. There were no effects on the survival of emerged seedlings for any species tested.

There were statistically-significant reductions in mean dry weight of A. sativa, B. napus and C. sativa. The reductions were not dose-responsive, and were all less than 20% in magnitude. However, due to the significant differences observed, the NOEC and LOEC for dry weight of these species were determined as noted above. The EC10 for B. napus based on dry weight was determined to be lower than the lowest test level. Meaningful 95% confidence limits were not determined for any EC10 values based on dry weight.

There were statistically-significant reductions in mean height of B. napus, C. sativa and G. max. Although significant differences were detected, the maximum reductions of B. napus and G. max from the control were 9% and 11%, respectively, and EC10 estimates could not be calculated. The mean heights for all treatment groups of C. sativa were significantly reduced relative to the control mean according to the results of Dunnett’s test (p<0.050). However, the reductions ranged from 11 to 16% from the control mean and were not dose-responsive. Therefore, a Jonckheere-Terpstra test was used to determine if a significant trend of decreasing mean height was present. Results of the Jonckheere-Terpstra indicated that the 62.5 mg/kg treatment group mean height was not significantly different from that of the pooled control groups. Therefore, the NOEC for C. sativa based on height was determined to be 62.5 mg/kg.
Validity criteria fulfilled:
yes
Conclusions:
Planting of seeds into soils with nominal test substance concentrations of up to 1000 mg/kg dry soil resulted in little or no adverse effects on the seedling emergence and early growth of all six species tested. All EC20 estimates were higher than the highest soil concentration tested.
Executive summary:

This seedling emergence study with Allium cepa, Avena sativa, Beta vulgaris, Brassica napus, Cucumis sativa and Glycine max was conducted for Sasol Italy S.p.A. at the Wildlife International greenhouse facility in Easton, Maryland.  The in-life phase of the test was conducted from September 15, to October 6, 2015 for all species.  The test species, two monocot and four dicot species of terrestrial non-target plants, were exposed to a series of five geometrically spaced test concentrations of Alkenes, C11-12, hydroformylation products, distn. residues incorporated in soil as well as a negative (water purified by reverse osmosis) and a solvent (tetrahydrofuran) control. Nominal test levels included: 0 (Negative and Solvent Controls), 62.5, 125, 250, 500 and 1000 milligrams test substance per kilogram of dry soil. Each test and control group consisted of eight replicate test pots, each containing 5 planted seeds of one species and placed on a greenhouse bench top according to a randomized block design. The test duration was 21 days following planting or at least 14 days after 50% emergence of control plants for each species. The number of emerged seedlings was observed weekly and the percentage of surviving seedlings, seeding height and dry weight were determined at test termination.

Planting of seeds into soils with nominal test substance concentrations of up to 1000 mg/kg dry soil resulted in little or no adverse effects on the seedling emergence and early growth of all six species tested.  All EC20 estimates were higher than the highest soil concentration tested.  The NOEC and ECx estimates based on the most sensitive endpoints for each species are summarized below.

Species

NOEC (mg/kg)

(endpoint)

EC10(mg/kg)

(endpoint)

EC20(mg/kg)

(endpoint)

Allium cepa

1000
(all parameters)

> 1000
(all parameters)

> 1000
(all parameters)

Avena sativa

250
(dry weight)

148
(dry weight)

> 1000
(all parameters)

Beta vulgaris

250
(emergence)

67.7
(emergence)

> 1000
(all parameters)

Brassica napus

62.5
(dry weight)

2.141
(dry weight)

> 1000
(all parameters)

Cucumis sativa

62.5
(height)

23.41
(height)

> 1000
(all parameters)

Glycine max

500
(height)

> 1000
(all parameters)

> 1000
(all parameters)

                                                                                    1Extrapolated below the lowest test concentration.

 

For Avena sativa the controls reported mean dry weight of 0.301 +/- 0.0371 (std. dev.), reflecting a C.V. of 12.3%. Based upon this elevated C.V., the lowest reliable estimator of toxicity upon Avena sativa dry weight is deemed to be the next larger incremental EC statistically calculated, which is the EC20.

For Beta vulgaris the controls reported mean emergence of 4.13 +/- 0.96 (std. dev.), reflecting a C.V. of 23.2%. Based upon this elevated C.V., the lowest reliable estimator of toxicity upon Beta vulgaris emergence is deemed to be the next larger incremental EC statistically calculated, which is the EC50. However, as the EC20 has already exceeded the highest concentration tested, it has been selected.

Brassica napus controls reported mean dry weight of 0.548 +/- 0.0975 (std. dev.), reflecting a C.V. of 17.8%. Based upon this elevated C.V., the lowest reliable estimator of toxicity upon Brassica napus dry weight is deemed to be the next larger incremental EC statistically calculated, which is the EC20.

Cucumis sativa controls showed a mean height of 23.6 +/- 2.59 (std. dev.), reflecting a C.V. of 10.9%. Based upon this elevated C.V., the lowest reliable estimated of toxicity upon Cucumis sativa height is deemed to be the next larger incremental EC statistically calculated, which is the EC20.

Description of key information

Planting of seeds into soils with nominal test substance concentrations of up to 1000 mg/kg dry soil resulted in little or no adverse effects on the seedling emergence and early growth of all six species tested.  All EC20 estimates were higher than the highest soil concentration tested.

Key value for chemical safety assessment

Long-term EC10, LC10 or NOEC for terrestrial plants:
1 000 mg/kg soil dw

Additional information

This seedling emergence study with Allium cepa, Avena sativa, Beta vulgaris, Brassica napus, Cucumis sativa and Glycine max was conducted for Sasol Italy S.p.A. at the Wildlife International greenhouse facility in Easton, Maryland. The in-life phase of the test was conducted from September 15, to October 6, 2015 for all species. The test species, two monocot and four dicot species of terrestrial non-target plants, were exposed to a series of five geometrically spaced test concentrations of Alkenes, C11-12, hydroformylation products, distn. residues incorporated in soil as well as a negative (water purified by reverse osmosis) and a solvent (tetrahydrofuran) control. Nominal test levels included: 0 (Negative and Solvent Controls), 62.5, 125, 250, 500 and 1000 milligrams test substance per kilogram of dry soil. Each test and control group consisted of eight replicate test pots, each containing 5 planted seeds of one species and placed on a greenhouse bench top according to a randomized block design. The test duration was 21 days following planting or at least 14 days after 50% emergence of control plants for each species. The number of emerged seedlings was observed weekly and the percentage of surviving seedlings, seeding height and dry weight were determined at test termination.

Planting of seeds into soils with nominal test substance concentrations of up to 1000 mg/kg dry soil resulted in little or no adverse effects on the seedling emergence and early growth of all six species tested. All EC20 estimates were higher than the highest soil concentration tested.