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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:
2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
Neopentyl Glycol Dipelargonate resulted not sufficiently soluble at the required concentrations in any of the solvents of the LuSens test. Also a performance of the h-CLAT test (as an alternative test ) is not possible due to the low solubility. So a LLNA study has been performed.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2018

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 442B (Skin Sensitization: Local Lymph Node Assay: BrdU-ELISA)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of study:
mouse local lymph node assay (LLNA): BrdU-ELISA

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
liquid
Details on test material:
Legal entity composition

In vivo test system

Test animals

Species:
mouse
Strain:
CBA:JN
Sex:
female
Details on test animals and environmental conditions:
Animal supply and acclimatisation
Age 7 weeks old
Supplier Charles River Italia S.p.A., Calco (Lecco), Italy
Breeder Charles River, Jackson, USA
Date of arrival 22 February 2018
Weight range at arrival 19.4 to 20.1 grams
Acclimatisation period At least 5 days
Veterinary health check During acclimatisation period

Animal husbandry
Animals per cage 5 during acclimatisation; 1/cage during the study
Housing Polysulfone solid bottomed cages measuring 35.5 × 23.5 × 19 cm with nesting material
Cagecontrol D aily 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:
Five concentrations [100, 50, 25,10 and 5% w/w in acetone:olive oil 4:1 (v/v)] were tested in the preliminary phase.
In the main assay, the test item was topically administered at the concentrations of 100, 50 and 25% (w/w), in acetone:olive oil 4:1 (v/v).
No. of animals per dose:
4
Details on study design:
Preliminary test
Dosing Frequency of treatment
The animals were treated for three consecutive days (Days 1, 2, 3) with the vehicle or test item formulations.Dosing method
A dose volume of 25 µL/ear/day of the appropriate concentration was applied to the dorsal surface of each ear (50 µL/animal/day), using a micropipette.

In vivo observations Mortality and morbidity
Throughout the study, all animals were checked twice daily.

Clinical signs
The animals were observed for clinical signs on: Day 1: before and approximately 1 hour after dosing Day 2 to 6: daily (approximately 1 hour after daily dosing, when applicable)

Body weight
The animals were weighed at allocation (Day 1) and on sacrifice (Day 6).

Scoring of dermal reaction
The treated sites of all animals were examined daily (once before first dosing, before dosing on Days 2 and 3 and daily thereafter).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 4
grading of erythema

Selection of dose levels
In the main assay, the test item was used at the higher concentrations that were systemically tolerated and judged not to cause excessive local skin irritation.In particular, concentrations are considered irritant if:
– erythema grading (score) is ≥ 3 at any day of measurement and/or
– ear thickness is ≥ 25% with respect to Day 1 and
– ear punch weight is ≥ 25% with reference to the negative control group

Main assay
Treatment schedule of animals is summarised as follows:

Day 1 Day 2 Day 3 Day 4 Day 5 Day 6 D D D — BrdU C

D : Dermal application of the test item, the positive control or vehicle at a dose volume of 25 µL/ear (50 µL/animal).
BrdU : Intraperitoneal administration of BrdU.
C : Sacrifice, processing of lymph nodes and determination of cell proliferation.

Dosing with the test or control items Frequency of treatment
The animals were treated for three consecutive days (Days 1, 2, 3) with the vehicle, test or control item formulations.

Dosing method
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.

5-bromo-2-deoxyuridine (BrdU) treatment
The animals were treated intraperitoneally, on Day 5 (once only), with 0.5 mL/animal of a solution of BrdU at a concentration of 10 mg/mL in physiological saline (0.9% NaCl), using a plastic graded syringe.

In vivo observations Mortality and morbidity
Throughout the study, all animals were checked twice daily.

Clinical signs
The animals were observed for clinical signs before dosing commenced and daily up to sacrifice (approximately 1 hour after dosing on Days 2, 3 and 5).

Body weight
The animals were weighed at allocation (Day 1) and on sacrifice (Day 6).

The animals were killed on Day 6, approximately 24 hours after BrdU injection, by carbon dioxide narcosis.
No necropsy was performed on the sacrificed animals. Shortly after sacrifice of each animal, the auricular lymph nodes were rapidly excised, pooled on individual basis and individually collected in a solution of 2 % BSA-PBS [2 % bovine serum albumine (BSA) in phosphate buffered saline, PBS]. Cell suspensions were prepared for the evaluation of proliferation at lymph node.

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. If data were found to be inhomogeneous, a Modified t test (Cochran and Cox) was applied.

Results and discussion

Positive control results:
The Stimulation Index (SI) of the positive control group was higher than 2.0.

In vivo (LLNA)

Resultsopen allclose all
Parameter:
SI
Value:
0.99
Test group / Remarks:
25 %
Parameter:
SI
Value:
1.31
Test group / Remarks:
50 %
Parameter:
SI
Value:
1.61
Test group / Remarks:
100 %
Cellular proliferation data / Observations:
A slight increase in cell proliferation of draining lymph nodes was observed in the high dose group [100% (w/w)], with a Stimulation Index
of 1.61, which is considered a borderline result. However, due to the absence of a statistical significance, the observed result is not considered sufficient to indicate a classification.

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
Classification Not required
Signal word None indicated
Hazard statement None indicated
Executive summary:

The potential of the test item, Matrilox CP201M, to cause skin sensitisation reactions following topical application to the skin of CBA/JN mice, was assessed using the LLNA:BrdUELISA method, according to the OECD Guideline for testing of chemicals No. 442b.

The calculated Stimulation Indices (SI) at the low and medium dose groups [25 % and 50 % (w/w)] were 0.99 and 1.31, respectively. A slight increase in cell proliferation of draining lymph nodes was observed in the high dose group [100 % (w/w)], with a Stimulation Index of 1.61, which is considered a borderline result. However, due to the absence of a statistical significance, the observed result is not considered sufficient to indicate a classification