Calcium carbonate

Toxicity to soil macroorganisms except arthropods

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to soil macroorganisms except arthropods: short-term

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
Bulk calcium carbonate and uncoated nano calcium carbonate are chemically identical. The only difference between them is the particle size, which may result in minor differences in physico-chemical properties. However, in biological systems and in the environment, both bulk and uncoated nano calcium carbonate are expected to have identical (eco)toxicological and environmental fate properties.
2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Uncoated nano calcium carbonate (Source): Refer to IUCLID section 1.2 for information on purity and impurities.
Bulk calcium carbonate (Target): Refer to IUCLID section 1.2 for information on purity and impurities.
The majority of new studies have been performed using uncoated nano calcium carbonate as the test material, hence it has been designated as the ‘Source’ in the read-across justification. However, for some endpoints data on bulk calcium carbonate are available and used to read-across to uncoated nano calcium carbonate so for these endpoints, marked with a * in the read-across justification document, bulk calcium carbonate is the ‘Source’.
3. ANALOGUE APPROACH JUSTIFICATION
Please refer to the justification attached in Section 13 of the dataset
4. DATA MATRIX
Please refer to the justification attached in Section 13 of the dataset

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

according to guideline

Guideline:

OECD Guideline 207 (Earthworm, Acute Toxicity Tests)

Deviations:

yes

Remarks:

Some of the temperatures were observed to be slightly in excess of the 20 ± 2 °C given in the study plan. However, this deviation was considered not to have affected the outcome or the validity of the test.

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

> 1 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

1 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: mortality and sub-lethal effects

Reference 2

Endpoint:

toxicity to soil macroorganisms except arthropods: long-term

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Description of key information

The acute toxicity of uncoated nano calcium carbonate to the earthworm Eisenia foetida has been investigated in a GLP artificial soil test performed in accordance with OECD Guideline 207. The 14 day LC50 value was >1000 mg/kg and the NOEC was 1000 mg/kg.

No long-term studies on terrestrial invertebrates are available .

Additional information

Acute Toxicity:

The key study for short term toxicity (Goodband, 2010) was performed to OECD TG 207 and in accordance with GLP. The study assessed the acute toxicity of uncoated nano calcium carbonate to Eisenia foetida in a limit test. There were no significant mortalities or sub-lethal effects observed as a result of exposure to uncoated nano calcium carbonate at a concentration of 1000 mg/kg in soil. Hence, the 14 day LC50 value was >1000 mg/kg and the NOEC was 1000 mg/kg. Uncoated nano calcium carbonate is therefore not toxic to earthworms up to a concentration of 1000 mg/kg.

Uncoated nano calcium carbonate was tested because it was anticipated to represent the worst case as it is likely to be more soluble than bulk calcium carbonate due to the smaller particle size and hence greater surface area. However, the results are directly applicable to bulk calcium carbonate.

Long Term Toxicity:

Calcium carbonate and calcium and carbonate ions are ubiquitous in the environment and are found naturally in soil, water and sediment.Calcium is an important constituent of most soils and the minerals found in soil are mostly compounds of calcium with other substances. Furthermore, calcium carbonate is used as an inorganic fertiliser to improve soil quality, both pH and structure and guarantees an adequate supply of calcium to plants.

Furthermore, in the acute toxicity study to earthworms there were no significant mortalities or sub-lethal effects of exposure observed in 60 earthworms exposed to uncoated nano calcium carbonate for a period of 14 days. As a result, calcium carbonate is considered not acutely toxic to earthworms and hence long term testing is considered to be unnecessary

Given the extensive and continued use of calcium carbonate as a constituent of fertiliser and its natural occurrence in the environment, it is considered that calcium carbonate would not have a detrimental effect on soil macroorganisms. Therefore, the performance of long term toxicity tests on terrestrial organisms is scientifically unjustified.