[No public or meaningful name is available]

Endpoint summary

Description of key information

A study was performed according to OECD Guideline 429 to assess the skin sensitisation potential of the read-across substance calcium carbonate (nano) in the CBA/Ca strain mouse following topical application to the dorsal surface of the ear. 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.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

13 January 2010 to 27 January 2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

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

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Specific details on test material used for the study:

Uncoated nano calcium carbonate

Species:

mouse

Strain:

other: CBA/Ca (CBA/CaOlaHsd)

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Harlan Laboratories UK Ltd, Bicester, Oxon, UK
- Age at study initiation: 8-12 weeks
- Weight at study initiation: 15-23 g
- Housing: individually in suspended solid-floor polypropylene cages
- Diet (e.g. ad libitum): 2014 Teklad Global Rodent diet ad libitum
- Water (e.g. ad libitum): tap water ad libitum
- Acclimation period: >= 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19-25
- Humidity (%): 30-70
- Air changes (per hr):15
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: To: 13/01/2010 - 27/01/2010

Vehicle:

dimethylformamide

Concentration:

5, 10 or 25 %w/w

No. of animals per dose:

4

Details on study design:

RANGE FINDING TESTS:
Using available information regarding the systemic toxicity/irritancy potential of the test material, a preliminary screening test was performed using one mouse. The mouse was treated by daily application of 25 µl of the test material at a concentration of 25 %w/w in dimethyl formamide to the dorsal surface of each ear for three consecutive days (Days 1, 2, 3). The mouse was observed twice daily on Days 1, 2 and 3 and once daily on Days 4, 5 and 6. Any signs of toxicity or excessive local irritation noted during this period were recorded. The bodyweight was recorded on Day 1 (prior to dosing) and on Day 6. No signs of systemic toxicity were noted. White staining on the ears was noted post dose on Days 2 and 3. Based on this information the dose levels selected for the main test were 25 %, 10 % and 5 %w/w in dimethyl formamide.

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: Local Lymph Node Assay in the Mouse. The assay has undergone extensive inter-laboratory validation and has been shown to reliably detect test materials that are moderate to strong sensitisers.
- Criteria used to consider a positive response: The proliferation response of lymph node cells was expressed as the number of radioactive disintegrations per minute per lymph node (disintegrations per minute/node) and as the ration of 3HTdR incorporation into lymph node cells of test nodes relative to that recorded for the control nodes (Stimulation Index). The test substance is regarded as a sensitiser if at least one concentration of the test substance results in a threefold or greater increase in 3HTdR incorporation compared to control values.

TREATMENT PREPARATION AND ADMINISTRATION: The test substance was freshly prepared as a suspension in dimethyl formamides. This vehicle was chosen as it produced the highest concentration that was suitable for dosing. The test substance was formulated within 2 hours of it being applied to the test system. No analysis was conducted to determine the homogeneity, concentration or stability of the formulation. The mice were treated by daily application of 25 µL of the appropriate concentration of the test substance to the dorsal surface of each ear for 3 consecutive days. The test substance was administered using an automatic micropipette and spread over the dorsal surface of the ear using the tip of the pipette.

Positive control substance(s):

hexyl cinnamic aldehyde (CAS No 101-86-0)

Positive control results:

The Stimulation Index expressed as the mean radioactive incorporation for the treatment group divided by the mean radioactive incorporation of the control groups was 5.16, hence the result was positive.

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

Disintegrations per minute at each concentration

Concentration (%w/w in dimethyl  formamide)	dpm	dpm/node
Vehicle	8246.81	1030.85
5	14319.64	1789.96
10	9325.17	1165.65
25	15632.46	1954.06

Interpretation of results:

GHS criteria not met

Conclusions:

The substance was considered to be a non-sensitiser under the conditions of the test.

Executive summary:

A study was performed according to OECD Guideline 429 to assess the skin sensitisation potential of calcium carbonate (nano) in the CBA/Ca strain mouse following topical application to the dorsal surface of the ear. 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.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Classification, Labelling, and Packaging Regulation (EC) No 1272/2008
The available data are reliable and suitable for classification purposes under Regulation (EC) No 1272/2008. Based on this data, the substance is not considered to be classified for skin sensitisation under Regulation (EC) No 1272/2008, as amended for the eighteenth time in Regulation (EU) 2022/692.