Calcium dihydroxide

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:

June 04, 2007 - July 02, 2007

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: According to OECD 208. Well documented GLP study. Validity criteria fulfilled.

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:

no

Details on sampling:

On day 21 after 50% seedling emergence, soil samples are taken for pH measurements.

Vehicle:

no

Details on preparation and application of test substrate:

TEST SOIL
Origin: agricultural soil from site Gerichshain (batch G 01/2007), stored for at least 1 year before used in the test
Soil type: sandy loam according to "AG Bodem" of BBA 1994, loam according to USDA
pH value (CaCl2): 5.9 (ISO 10390)
C(org): 0.9%
Humus content: 1.5%
Water holding capacity: 38.8 g/100 g dry soil
Particle size: 9.9% < 0.002 mm (clay), 45.9% between 0.002 and 0.063 mm (silt) and 44.3% between 0.063 and 2.0 mm (sand)
No pesticides or fertilisers were applied on the origin plot of the used soil for at least 5 years because the plot was fallow land

Species:

Beta vulgaris

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

Common name: sugar beet
Variety: Achat
PSeeds prchased from: Strube-Dieckmann GmbH & Co. KG, Söllingen
Batch: SD04-04-07-19
Determined germination rate: 94%

Species:

Brassica napus

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

Common name: oilseed rape
Variety: Express
Seeds purchased from: Saaten-Union GmbH, Isernhagen
Batch: SU03-04-07-17
Determined germination rate: 96%

Species:

other: Spinacia oleracea

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

Common name: spinach
Variety: Lavewa
Seeds purchased from: N.L. Chrestensen, Erfurt
Batch: 455815
Determined germination rate: 94%

Species:

Pisum sativum

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

Common name: pea
Variety: Maxigolt
Seeds purchased from: Dehner Gartencenter, Taucha
Batch: 2924
Determined germination rate: 90%

Species:

Triticum aestivum

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

Common name: wheat
Variety: Tommi
Seeds purchased from: Saaten-Union GmbH, Isernhagen
Batch: SU03-04-07-18
Determined germination rate: 98%

Species:

other: Allium porrum

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

Common name: leek
Variety: Genita
Seeds purchased from: Dehner Gartencenter, Taucha
Batch: 1665
Determined germination rate: 88%

Test type:

early seedling growth toxicity test

Study type:

laboratory study

Substrate type:

artificial soil

Limit test:

no

Total exposure duration:

21 d

Remarks:

21 days after 50% seedling emergence in the control group

Test temperature:

16-36°C (short-term temperature over 40°C)

pH:

pH test soil: 5.9
pH at day 0: 5.9 - 9.4
pH at end test: 5.7 - 9.0

Moisture:

Relative humidity: 25-92% (short-term relative humidity under 45%)

Details on test conditions:

PREPARATION
The test item was incorporated directly into the soil by mixing with the soil in a mixing machine.

TEST CONDITIONS
Test pot: plastic flower pot (Ø 15 cm), amount 1.0 kg
Number of plants/pot: 3 for Pisum sativum, 4 for Brassica napus, Beta vulgaris and Spinacia oleracea and 5 for Triticum aestivum and Allium porrum.
Number of pots: 14 for Pisum sativum, 10 for Brassica napus, Beta vulgaris and Spinacia oleracea and 8 for Triticum aestivum and Allium porrum.
Number of seeds/treatment: 40-42
Fertilising: Pflanzenvollnahrung (Dehner Gartenzentrum)
Fertilizer nutrients: 4% N, 3% P2O5 and 3% K2O
Fertilizer dressing: once, 7 days after germination
Fertilizer solution: 100 ml/pot
Irrigation: daily with 40 ml tap water (room temperature, pH 7.3 and conductivity 580 µs/cm)

CLIMATIC TEST CONDITIONS
Relative humidity: 25-92% (short-term relative humidity under 45%)
Illumination: light period: 16 h (including 6h HQL-light)

Nominal and measured concentrations:

Nominal concentrations: 0, 0.51, 1.08, 2.27, 4.76 and 10.0 g test item/kg soil dry weight.

Reference substance (positive control):

no

Species:

other: Allium porrum

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

5.64 g/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

Ca(OH)2

Basis for effect:

seedling emergence

Remarks on result:

other: NOEC for seedling emergence: 2.27 g/kg dw

Species:

other: Allium porrum

Duration:

21 d

Dose descriptor:

LC50

Effect conc.:

10.83 g/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

Ca(OH)2

Basis for effect:

other: seedling survival

Species:

other: Allium porrum

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

3.53 g/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

Ca(OH)2

Basis for effect:

other: shoot fresh weight

Remarks on result:

other: NOEC: 2.27 g/kg dw; LOEC: 4.76 g/kg dw

Species:

Beta vulgaris

Duration:

21 d

Dose descriptor:

other: EC50 and LC50

Effect conc.:

> 10 g/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

Ca(OH)2

Basis for effect:

other: seedling emergence (7 days) and survival (21 days)

Remarks on result:

other: NOEC for seedling emergence: 4.76 g/kg dw

Species:

Beta vulgaris

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

3.8 g/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

Ca(OH)2

Basis for effect:

other: shoot fresh weight

Remarks on result:

other: NOEC: 1.08 g/kg dw; LOEC: 2.27 g/kg dw

Species:

Brassica napus

Duration:

21 d

Dose descriptor:

other: EC50 and LC50

Effect conc.:

> 10 g/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

Ca(OH)2

Basis for effect:

other: seedling emergence (day 7) and survival (day 21)

Remarks on result:

other: NOEC for seedling emergence: 10 g/kg dw

Species:

Brassica napus

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

4.15 g/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

Ca(OH)2

Basis for effect:

other: shoot fresh weight

Remarks on result:

other: NOEC: 1.08 g/kg dw; LOEC: 2.27 g/kg dw

Species:

Pisum sativum

Duration:

21 d

Dose descriptor:

other: EC50 and LC50

Effect conc.:

> 10 g/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

Ca(OH)2

Basis for effect:

other: seedling emergence (7 days) and survival (21 days)

Remarks on result:

other: NOEC for seedling emergence: 4.76 g/kg dw

Species:

Pisum sativum

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

6.18 g/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

Ca(OH)2

Basis for effect:

other: shoot fresh weight

Remarks on result:

other: NOEC: 2.27 g/kg dw; LOEC: 4.76 g/kg dw

Species:

other: Spinacea oleracea

Duration:

21 d

Dose descriptor:

other: EC50 and LC50

Effect conc.:

> 10 g/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

Ca(OH)2

Basis for effect:

other: seedling emergence (7 days) and survival (21 days)

Remarks on result:

other: NOEC for seedling emergence: 4.76 g/kg dw

Species:

other: Spinacea oleracea

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

2.67 g/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

Ca(OH)2

Basis for effect:

other: shoot fresh weight

Remarks on result:

other: NOEC: 1.08 g/kg dw; LOEC: 2.27 g/kg dw

Species:

Triticum aestivum

Duration:

21 d

Dose descriptor:

other: EC50 and LC50

Effect conc.:

> 10 g/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

Ca(OH)2

Basis for effect:

other: seedling emergence (day 7) and survival (day 21)

Remarks on result:

other: NOEC for seedling emergence: 10 g/kg dw

Species:

Triticum aestivum

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

5.14 g/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

Ca(OH)2

Basis for effect:

other: shoot fresh weight

Remarks on result:

other: NOEC: 2.27 g/kg dw; LOEC: 4.76 g/kg dw

Species:

other: Allium porrum

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

2.27 g/kg soil dw

Nominal / measured:

not specified

Conc. based on:

test mat.

Remarks:

Ca(OH)2

Basis for effect:

other: shoot fresh weight

Species:

Triticum aestivum

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

2.27 g/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

Ca(OH)2

Basis for effect:

other: shoot fresh weight

Species:

Brassica napus

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

1.08 g/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

Ca(OH)2

Basis for effect:

other: shoot fresh weight

Species:

Beta vulgaris

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

1.08 g/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

Ca(OH)2

Basis for effect:

other: shoot fresh weight

Species:

other: Spinacia oleracea

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

1.08 g/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

Ca(OH)2

Basis for effect:

other: shoot fresh weight

Species:

Pisum sativum

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

2.27 g/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

Ca(OH)2

Basis for effect:

other: shoot fresh weight

Species:

other: Allium porrum

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

4.76 g/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

Ca(OH)2

Basis for effect:

other: shoot fresh weight

Species:

Triticum aestivum

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

4.76 g/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

Ca(OH)2

Basis for effect:

other: shoot fresh weight

Species:

Brassica napus

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

2.27 g/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

Ca(OH)2

Basis for effect:

other: shoot fresh weight

Species:

Beta vulgaris

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

2.27 g/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

Ca(OH)2

Basis for effect:

other: shoot fresh weight

Species:

other: Spinacia oleracea

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

2.27 g/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

Ca(OH)2

Basis for effect:

other: shoot fresh weight

Species:

Pisum sativum

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

4.76 g/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

Ca(OH)2

Basis for effect:

other: shoot fresh weight

Details on results:

Seedling emergence in the control: ≥ 70%
Mean survival of emerged control seedlings: ≥ 90%
Seedling do not exhibit visible phytotoxic effects in the control and the plants exhibit only normal variation growth and morphology for that particular species.

Upon addition of the test item to the soil, a rapid increase in soil pH from 6.1 to 6.9, 7.7, 8.4, 8.9 and 9.4 respectively was observed. The soil pH decreased again during the course of the study. Additional pH measurements of soil samples were analysed without air-drying. The results indicate that the initial soil pH was underestimated as a result of carbonisation of the test item during air-drying of the soil samples.

Growth inhibition was observed in all plants especially at 4.76 and 10 g/kg dw.

Validity criteria fulfilled:

yes

Conclusions:

The results of the test indicate that of the six crop species tested, the dicotyledonae Brassica napus, Beta vulgaris and Spinacia oleracea and the monocytyledonae Allium porrum were most sensitive to the effects of Calcium dihydroxide (hydrated lime). Survival after seedling emergence (LC50) was only affected in the monocotyledonae Allium porrum.
Upon addition of the test item to the soil, a dose-dependent increase in soil pH was observed. In the course of the study, the pH value decreased. The increase in pH value of the soil after addition of Calcium dihydroxide is considered to determine the toxicity to plants.

Description of key information

Klimisch 1 study (Friedrich; 2007): 21-day seedling growth test according to OECD 208 with 6 plant species; nominal NOEC varies between 1080 and 2270 mg Ca(OH)2/kg soil dw.

Key value for chemical safety assessment

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

1 080 mg/kg soil dw

Additional information

The short term toxicity to plants of calcium dihydroxide (hydrated lime) was assessed in a study performed to OECD TG 208 under GLP (Friedrich, 2007c). The study assessed the effects on seedling emergence and growth of calcium dihydroxide to six species of plant (sugar beet, oilseed rape, spinach, pea, wheat and leek). The results of the test indicate that of the six species tested, oilseed rape, sugar beet, spinach and leek were most sensitive to the effects of calcium dihydroxide. Survival after seedling emergence (LC50) was only affected in leeks. Upon addition of the test item to the soil, a dose-dependent increase in soil pH was observed. In the course of the study, the pH value decreased. The increase in pH value of the soil after addition of calcium dihydroxide is considered to determine the toxicity to plants.

The short term toxicity to plants of calcium carbonate (nano) was assessed in a study performed to OECD TG 208 under GLP (Goodband, 2010). The study assessed the effects on seedling emergence and growth of calcium carbonate (nano) to three species of plant (soybean, tomato and oat) in a limit test. No toxic effects on either growth or seedling emergence were noted at the concentration tested. Hence, the 21 day EC50 for calcium carbonate (nano) was found to be >1000 mg/kg dw soil and the NOEC was 1000 mg/kg dw soil.

No long-term studies are available for calcium carbonate, but given the ubiquitous nature of calcium and carbonate ions in the environment and the use of calcium carbonate as an inorganic fertiliser to improve soil quality, both pH and structure, and to guarantee an adequate supply of calcium to plants no long term detrimental effects are expected from exposure of plants to calcium carbonate.

Both calcium dihydroxide and calcium carbonate gave similar 21-day NOEC values in OECD TG 208 studies of 1080 and 1000 mg/kg soil dw, respectively. Therefore, it may be concluded that grades of calcium dihydroxide containing up to 35% calcium carbonate will have similar toxicity to plants. In fact, it could be argued that due to the much lower solubility of calcium carbonate, the pH-related effects seen at higher concentrations of calcium dihydroxide would not occur to the same extent in grades with a high calcium carbonate content.