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Toxicity to terrestrial plants

Link to relevant study record(s)

Reference

Endpoint:

toxicity to terrestrial plants: short-term

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

26 March 2010 to 16 August 2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

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)

Specific details on test material used for the study:

Uncoated nano CaCO3

Analytical monitoring:

no

Vehicle:

no

Details on preparation and application of test substrate:

- Method of mixing into soil (if used): The test material was added directly to the soil. An amount of test material (10.2 g) was mixed with approximately 200 g of sand prior to incorporation into 5.05 kg of sand and 5.1 kg (dry weight) of soil using a Hobart A200N mixer to give the 1000 mg/kg test concentration.
- Controls: The control was prepared by mixing 5.45 kg sand with 5.1 kg (dry weight) of soil without the addition of test item.

Species:

Glycine max (G. soja)

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Soybean
- Variety: Amsoy
- Source of seed: Herbiseed, New Farm, Mire Lane, West End, Twyford, UK
- Prior seed treatment/sterilization: None
- Historical germination of seed (germination of seed lot tested): 86%
- Seed storage: Upon arrival the seeds were stored under cool, dry conditions.

Species:

Lycopersicon esculentum

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Tomato
- Variety: Orange Pixie
- Source of seed: Herbiseed, New Farm, Mire Lane, West End, Twyford, UK
- Prior seed treatment/sterilization: None
- Historical germination of seed (germination of seed lot tested): 91%
- Seed storage: Upon arrival the seeds were stored under cool, dry conditions.

Species:

Avena sativa

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Oat
- Variety: SW Argyle
- Source of seed: Senova Ltd., 49 North Road, Great Abington, Cambridge, UK
- Prior seed treatment/sterilization: None
- Historical germination of seed (germination of seed lot tested): 87%
- Seed storage: Upon arrival the seeds were stored under cool, dry conditions.

Test type:

other: seedling emergence and growth test

Study type:

laboratory study

Substrate type:

artificial soil

Limit test:

yes

Total exposure duration:

21 d

Test temperature:

13 - 39 °C

Moisture:

25 - 87%

Details on test conditions:

TEST SYSTEM
- Testing facility: A greenhouse at Harlan Laboratories Ltd, Shardlow Business Park, Shardlow, Derbyshire, DE72 2GD, UK
- Test container (type, material, size): The exposure vessels consisted of polypropylene pots with a depth of 9.9 cm and a diameter of 13 cm. After planting, each pot was placed in a plant saucer which served as a sub-irrigation reservoir. Initial watering was via the surface to encourage germination. All subsequent watering was by sub-irrigation as required.
- Amount of soil: Each pot contained approximately 850 g (dry weight) of substrate.
- No. of seeds per container: 5 seeds/ container
- No. of replicates per treatment group: 4 replicates
- No. of replicates per control: 4 replicates

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Soil classification system: sandy loam
- Composition (if artificial substrate):
- Organic carbon (%): 1.5%
- Pretreatment of soil: The soil was characterised as a sandy loam with 3.8% organic matter content and a pH of 8.0. The organic matter content of the soil was in excess of the 1% to 3% given in the study plan. Therefore the soil was mixed 50:50 w/w with sand prior to use which resulted in an organic carbon content of 1.5% (equivalent to 3% organic matter).

GROWTH CONDITIONS
- Photoperiod: 16 hours light and 8 hours darkness
- Day/night temperatures: 13 - 39 °C
- Relative humidity (%): 25 - 87%
- Watering regime and schedules: After the initial watering the pots were watered as necessary using sub-irrigation.

EFFECT PARAMETERS MEASURED: All the pots were monitored daily after sowing for emergence and the date when 50% emergence occurred in the control pots for each species was recorded. For 21 days following 50% emergence in the control pots, the number of seedlings emerged and any mortalities and/or morphological abnormalities were determined daily in the test and control pots for each species. On Day 21 the above ground portion of each seedling was harvested and the dry weight determined by placing in pre-weighed containers and drying in an oven at approximately 60°C.

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: nominal test concentrations of 100 and 1000 mg/kg
- Results used to determine the conditions for the definitive study: During the range-finding test the soybean failed to emerge due to an unknown factor. As a result, the concentrations to be used for the definitive test were based on the results from the remaining two species only.
There were no significant differences (P≥0.05) between the control and all the test groups in terms of emergence at test termination for tomato and oat.
There were no significant decreases in shoot dry weight (P≥0.05) between the control and all the test groups at test termination for tomato and oat.
Based on this information, a single test concentration of four replicates, of 1000 mg/kg was selected for each species for the definitive test. This experimental design conforms to a "Limit test" to confirm that at the maximum test concentration given in the OECD/EEC Test Guidelines no effect on seedling emergence or morphological abnormalities were observed.

Nominal and measured concentrations:

Nominal concentration: 1000 mg/kg

Reference substance (positive control):

no

Key result

Species:

other: All species tested (soybean, tomato and oat)

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

seedling emergence

Key result

Species:

other: All species tested (soybean, tomato and oat)

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth

Key result

Species:

other: All species tested (soybean, tomato and oat)

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: growth and seedling emergence

Details on results:

EMERGENCE DATA
Soybean (Glycine max), tomato (Lycopersicon esculentum) and oat (Avena sativa) reached 50% emergence in the control on Day 6, 7 and 6 respectively after sowing.
There were no significant differences (P≥0.05) between the control and 1000 mg/kg test group in terms of seedling emergence.

MORPHOLOGICAL EFFECTS
No morphological abnormalities were observed for each species throughout the test.

SHOOT DRY WEIGHT DATA
There were no significant differences (P≥0.05) between the control and 1000 mg/kg test group in terms of shoot dry weight at test termination for all three species.

Some of the temperatures were observed to be outside the 10°C to 35 °C range given in the study plan. This deviation was considered not to affect the integrity or the outcome of the study as no morphological abnormalities were observed throughout the test. 

Table 1: Percentage Emergence of Soybean (Glycine max) in the Definitive Test

Crop	Concentration (mg/kg)	Replicate	% emergence	Mean	Standard deviation
Soybean (Glycine max)	Control	1	60	75	30
		2	100
		3	100
		4	40
	1000	1	60	50	12
		2	40
		3	60
		4	40

 

 

Table 2: Percentage Emergence of Tomato (Lycopersicon esculentum) in the Definitive Test

Crop	Concentration (mg/kg)	Replicate	% emergence	Mean	Standard deviation
Tomato (Lycopersicon esculentum)	Control	1	80	70	12
		2	60
		3	60
		4	80
	1000	1	40	55	19
		2	60
		3	80
		4	40

 

 

Table 3: Percentage Emergence of Oat (Avena sativa) in the Definitive Test

Crop	Concentration (mg/kg)	Replicate	% emergence	Mean	Standard deviation
Oat (Avena sativa)	Control	1	60	70	20
		2	60
		3	100
		4	60
	1000	1	60	75	30
		2	100
		3	40
		4	100

 

 

Table 4: Shoot Mean Dry Weights - Soybean (Glycine max)

Crop	Concentration (mg/kg)	Replicate	Replicate weight (g)		Overall
			Mean	Standard deviation	Mean	Standard deviation
Soybean (Glycine max)	Control	1	0.4170	0.0123	0.3494	0.1066
		2	0.2879	0.0446
		3	0.3181	0.0912
		4	0.6114	N/A
	1000	1	0.3251	0.0193	0.3255	0.0535
		2	0.3385	0.0863
		3	0.2984	0.0791
		4	0.3540	0.0307

 

 

Table 5: Shoot Mean Dry Weights -Tomato (Lycopersicon esculentum)

Crop	Concentration (mg/kg)	Replicate	Replicate weight (g)		Overall
			Mean	Standard deviation	Mean	Standard deviation
Tomato (Lycopersicon esculentum)	Control	1	0.1267	0.1021	0.1257	0.0680
		2	0.0862	0.0109
		3	0.1726	0.0301
		4	0.1171	0.0727
	1000	1	0.0693	0.0497	0.0795	0.0867
		2	0.0607	0.0962
		3	0.0888	0.1070
		4	0.0990	0.1322

 

 

Table 6: Shoot Mean Dry Weights -Oat (Avena sativa)

Crop	Concentration (mg/kg)	Replicate	Replicate weight (g)		Overall
			Mean	Standard deviation	Mean	Standard deviation
Oat (Avena sativa)	Control	1	0.1155	0.0900	0.1464	0.0678
		2	0.1615	0.0556
		3	0.1201	0.0410
		4	0.1972	0.0828
	1000	1	0.1377	0.0741	0.1256	0.0595
		2	0.1085	0.0358
		3	0.1045	0.1201
		4	0.1438	0.0603

 

Validity criteria fulfilled:

yes

Remarks:

All the validity criteria specified in OECD TG 208 are satisfied

Conclusions:

The toxicity of calcium carbonate (nano) to three species of plant (soybean, tomato and oat) has been investigated and gave a 21 day EC50 of >1000 mg/kg dw soil based on both the seedling emergence and growth. Correspondingly the NOEC was 1000 mg/kg dw soil.
This study showed that there were no toxic effects to plants at the concentration tested.

Description of key information

The toxicity of calcium carbonate (nano, Read-Across substance) to three species of plant (soybean, tomato and oat) has been investigated and gave a 21 day EC50 of >1000 mg/kg dw soil based on both the seedling emergence and growth. Correspondingly the NOEC was 1000 mg/kg dw soil. This study showed that there were no toxic effects to plants at the concentration tested.