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Toxicological information

Skin sensitisation

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Administrative data

Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Start of experimental phase: 23 August 2017 End of experimental phase: 04 September 2017 Study completion: 06 November 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2017
Report Date:
2017

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 442B (Skin Sensitization: Local Lymph Node Assay: BrdU-ELISA)
Version / remarks:
Adopted on 22 July 2010
Deviations:
no
GLP compliance:
yes
Type of study:
mouse local lymph node assay (LLNA): BrdU-ELISA

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder

In vivo test system

Test animals

Species:
mouse
Strain:
CBA:JN
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
Species and strain: Mice, CBA/JN
Sex: Females (nulliparous and non-pregnant)
Age: 7 weeks old
Supplier: Charles River Italia S.p.A., Calco (Lecco), Italy
Breeder: Charles River, Jackson USA
Date of arrival: 10 August 2017
Weight range at arrival: 16 to 18 grams
Acclimatisation period: At least 5 days
Veterinary health check: During acclimatisation period

ENVIRONMENTAL CONDITIONS
Animals per cage: Up to 5 during acclimatisation; 1/cage during the study
Housing: Polysulfone solid bottomed cages measuring 35.5 × 23.5 × 19 cm with nesting material
Cage control: Daily inspected and changed as necessary (at least twice/week)
Water: drinking water supplied to each cage via a water bottle
Water supply: ad libitum
Diet: 4 RF 21 (Mucedola S.r.l., Via G. Galilei, 4, 20019, Settimo Milanese (MI) Italy)
Diet supply: ad libitum throughout the study
Room lighting: Artificial (fluorescent tubes), daily light/dark cycle of 12/12 hours
Air changes: Approximately 15 to 20 air changes per hour
Temperature range: 22°C±2°C
Relative humidity range: 55%±15%

Study design: in vivo (LLNA)

Vehicle:
acetone/olive oil (4:1 v/v)
Concentration:
Test item: 25, 10 and 5% (w/w).
Positive control: approximately 29% (w/w)
No. of animals per dose:
4 animals per dose
Details on study design:
PRE-SCREEN TESTS:
- Compound solubility:A solubility trial was performed in order to establish if acetone/olive oil 4:1 v/v could be used as a vehicle. A good suspension suitable for application was obtained at a concentration of 25% w/w in acetone/olive oil 4:1 v/v.
- Irritation: The treated sites of all animals were examined daily (once before first dosing, before dosing on Days 2 and 3 and daily thereafter).
- Systemic toxicity: The animals were observed for clinical signs on: Day 1: before and 1 hour after dosing Day 2 to 6: daily (approximately 1 hour after daily dosing, when applicable)
- Ear thickness measurements: The ear thickness was measured by a suitable micrometer on Day 1 (before dosing), on Day 3 (before dosing) and on Day 6.
- Erythema scores:Irritation to the skin was assigned a numerical value according to the table below:
Erythema and eschar formation Value
No erythema 0
Very slight erythema 1
Well defined erythema 2
Moderate to severe erythema 3
Severe erythema (beet redness) to eschar formation preventing grading of erythema 4

MAIN STUDY

ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: LOCAL LYMPH NODE ASSAY (LLNA: BrdU-ELISA method)
- Criteria used to consider a positive response: The test item is considered to induce sensitisation when the SI for any single treatment dose group is ≥ 1.6. It is not required that an increased response is observed at increasing dose levels, but dose-related activity and/or statistical significance may be taken as further evidence of a sensitisation effect (i.e. in case of borderline results with 1.6 ≤ SI ≤ 1.9).

TREATMENT PREPARATION AND ADMINISTRATION:The animals were treated for three consecutive days (Days 1, 2, 3) with the vehicle, test or control item formulations. A dose volume of 25 μL/ear/day of each selected concentration and controls was applied to
the dorsal surface of each ear (50 μL/animal/day), using a micropipette.
Positive control substance(s):
hexyl cinnamic aldehyde (CAS No 101-86-0)
Statistics:
Differences between each treated group and the concurrent negative control group (individual BrdU labelling indices) were assessed by Dunnett’s test. The homogeneity of the data was verified by Bartlett’s test before Dunnett’s test.

Results and discussion

Positive control results:
In the group treated with the positive control item, a Stimulation Index of 4.56 was calculated. As it was greater than 2, the study was regarded as valid.

In vivo (LLNA)

Resultsopen allclose all
Parameter:
SI
Value:
0.99
Test group / Remarks:
5%
Parameter:
SI
Value:
1.34
Test group / Remarks:
10%
Parameter:
SI
Value:
1.09
Test group / Remarks:
25%
Cellular proliferation data / Observations:
CELLULAR PROLIFERATION DATA: No significant increase in cell proliferation of draining lymph nodes was observed in any treatment group.
DETAILS ON STIMULATION INDEX CALCULATION: The calculated Stimulation Indices (SI) were 0.99, 1.34 and 1.09, respectively at low, mid- and high dose levels, respectively.
CLINICAL OBSERVATIONS: Neither mortality nor clinical signs were recorded in animals treated at all dose levels investigated [25, 10 and 5% (w/w)].
BODY WEIGHTS: Changes in body weight observed during the study were within the expected range for this strain and age of animals.

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
No increase in cell proliferation of draining lymph nodes was observed in any treatment group. The calculated Stimulation Indices were 0.99, 1.34 and 1.09 at low, mid- and high dose levels, respectively. Hence, the test item does not elicit any sensitisation response in mice following dermal exposure.
Executive summary:

The potential of the test item, Vat Red 32, to cause skin sensitisation reactions following topical application to the skin of CBA/JN mice, was assessed using the LLNA:BrdU-ELISA method, according to the OECD Guideline for testing of chemicals No. 442b.

Preliminary test

Five concentrations [25 (maximum feasible concentration), 10, 5, 2.5 and 1% w/w in acetone/ olive oil 4:1 (v/v)] were tested in the preliminary phase, in order to identify a non toxic and minimally irritant concentration and avoid false positive results.

No signs of toxicity (significant clinical signs or body weight losses) were observed at the tested concentrations.

According to the results of the irritation screening, the concentration of 25% w/w was judged to be not irritant.

Main assay

In the main assay, the test item was topically administered at the concentrations of 25, 10 and 5% (w/w), in acetone/olive oil 4:1 (v/v).

No mortality or clinical signs were recorded in any animal.

Changes in body weight observed during the study were within the expected range for this strain and age of animals.

No increase in cell proliferation of draining lymph nodes was observed in any treatment group. The calculated Stimulation Indices (SI) were 0.99, 1.34 and 1.09 at the low, midand high dose levels [5, 10 and 25%,], respectively. Neither correlation with the doses nor statistical significance was observed.

The above results indicate that the test item does not elicit any sensitisation response in mice following dermal exposure.

European Directives concerning the classification, packaging and labelling of dangerous substances (Council Regulation (EC)No. 1272/2008 and subsequent revisions) would indicate the following:

Classification Not required

Signal word None indicated

Hazard statement None indicated