Calcium carbonate

Endpoint summary

Description of key information

Bulk calcium carbonate is not a skin sensitiser.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Endpoint:

skin sensitisation: in vivo (LLNA)

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 429 (Skin Sensitisation: Local Lymph Node Assay)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)

Deviations:

no

Specific details on test material used for the study:

Bulk calcium carbonate

Parameter:

SI

Value:

1.74

Test group / Remarks:

5 %w/w

Parameter:

SI

Value:

1.13

Test group / Remarks:

10 %w/w

Parameter:

SI

Value:

1.19

Test group / Remarks:

25 %w/w

Interpretation of results:

GHS criteria not met

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

No data are available for bulk calcium carbonate. However, a study is available for uncoated nano calcium carbonate. In the study, performed according to OECD TG 429 under GLP, the substance was applied topically to the dorsal surface of the ears of mice (CBA/Ca) [Bradshaw 2010]. Three groups, each of four animals, were treated with 50 µL (25 µL per ear) of the test substance as a suspension in dimethyl formamide at concentrations of 5 %, 10 % or 25 %w/w. A further group of four animals was treated with dimethyl formamide alone. The Stimulation Index expressed as the mean radioactive incorporation for each treatment group divided by the mean radioactive incorporation of the vehicle control group was 1.74, 1.13 and 1.19 at concentrations of 5, 10 and 25 %w/w, respectively. The test material was considered to be a non sensitiser under the conditions of the test.

The nano form of calcium carbonate was tested because this form was anticipated to represent the worst case as the smaller size particles are more likely to be transported through the skin. However, the results are directly applicable to the bulk form of calcium carbonate.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Based on the results of an OECD TG 429 study performed using nano calcium carbonate and read across to bulk calcium carbonate, where the Stimulation Index was < 3, bulk calcium carbonate is considered to be a non-sensitiser and does not require classification.