[No public or meaningful name is available]

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

July 2022

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2022

Report date:

2022

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

Anatase, rutile, disodium hexatitanate and sodium tetratitanate

IUPAC Name:

Anatase, rutile, disodium hexatitanate and sodium tetratitanate

Specific details on test material used for the study:

Batch No.: OP.1501019

In vivo test system

Test animals

Species:

mouse

Strain:

CBA:J

Sex:

female

Details on test animals and environmental conditions:

8 (2 mice/group) female mice aged between 9 and 11 weeks were used for preliminary assay and 25 (5 mice/group) female mice between 9 and 11 weeks for main study. The animals were nulliparous and non-pregnant.
The rats were provided with feed (1334-P Maintenance Diet -Rat/mice) and water (UV sterilised water) ad libitum. Moreover, environmental conditions were strictly controlled: the temperature was between 19 to 23 °C with a relative humidity of 49-58% and a minimum 15 air changes/hour.

Study design: in vivo (LLNA)

Vehicle:

dimethyl sulphoxide

Concentration:

The test substance was tested at concentrations of 5% - 10% - 25% (w/w).
The preliminary assay was performed for the selection of the doses.During the preliminary assay no eryhtema was observed and an increase of less than 25% in ear thickness was observed at tested concentrations of 2.5% - 5% - 10% - 25%.

No. of animals per dose:

5 mice were used for group: G1, vehicle control; G2, 5% test substance; G3, 10% test substance; G4, 25% test substance; G5, positive control.

Details on study design:

PRELIMINARY STUDY:
four groups of mice comprising 2 females per group were treated with the test substance, applied at 2.5%, 5%, 10% and 25% (w/w) in Dimethylsulphoxide (DMSO) (25 µL/ear) for three consecutive days (days 0, 1 and 2). Clinical observations (including systemic clinical signs and scoring of irritation) were recorded daily during the experiment. Ear thickness was measured on days 0, 2 and 5. Body weight was recorded on days 0 and 5.

MAIN STUDY:
Three groups (G2 to G4) were treated topically for three consecutive days (days 0, 1 and 2) on the dorsal surface of both ears (25 L/ear) with the test substance at concentrations of 5%, 10% and 25% (w/w) the test substance in dimethylsulphoxide, respectively. Mice from vehicle control group (G1) and positive control group (G5) were handled in the same manner but received 25 L/ear of vehicle Dimethylsulphoxide (DMSO) and 25% a-Hexylcinnamaldehyde (v/v) in vehicle (Dimethylsulphoxide (DMSO)), respectively.

Positive control substance(s):

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

Statistics:

Statistical analysis was carried out for the assessment of the dose response relationship and pair-wise comparison made between the treatment and the solvent/vehicle control group. All the parameters characterised by continuous data such as body weight was subjected to Bartlett’s test.

However, as the DPM was not homogenous it was directly subjected to Student’s t-test. To compare vehicle and positive control data, Student’s t-test was performed to calculate significance.

Results and discussion

Positive control results:

A positive response for HCA (a-hexylcinnamaldehyde) of SI=6.85 confirmed the reliability of the test procedure.
The test item is regarded as a skin sensitiser when the SI for a dose group is > 3 together with consideration of a dose-response relationship.

In vivo (LLNA)

Results

Results 1

Key result

Parameter:

SI

Value:

ca. 2.16

Test group / Remarks:

G4: test substance concentration of 25%

Results 2

Key result

Parameter:

SI

Value:

ca. 1.69

Test group / Remarks:

G3: test substance concentration of 10%

Results 3

Key result

Parameter:

SI

Value:

ca. 1.18

Test group / Remarks:

G2: test substance concentration of 5%

Cellular proliferation data / Observations:

A statistically significant increase in DPM was observed at 25% (w/w) test substance in Dimethylsulphoxide (DMSO) and 25% (v/v) a-Hexylcinnamaldehyde in DMSO when compared to vehicle control group values (see Table below).

Any other information on results incl. tables

Table 1

Group N°	Dose Concentration (%)	N° of Mice Used	Group Mean DPM	Stimulation Index (SI)
G1	Dimethylsulphoxide (DMSO)	5	1030.60 ± 91.51	1
G2	5% Recovery titanium for ceramic frits (w/w)	5	1220.60 ± 531.91	1.18
G3	10% Recovery titanium for ceramic frits (w/w)	5	1738.00 ± 406.87	1.69
G4	25% Recovery titanium for ceramic frits (w/w)	5	2225.20↑ ± 534.37	2.16
G5	25% HCA (v/v)	5	7062.20 ↑↑ ± 2128.34	6.85

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Under test conditions, the test item was not a skin sensitiser.