Schiff bases, benzylidene, C16-18 (even numbered) and C18-unsaturated alkyl

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

23rd December 2015- 1st February 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2016

Report date:

2016

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

GLP compliance:

yes

Type of study:

Buehler test

Justification for non-LLNA method:

A Buehler test was used for R&D purposes and worldwide acceptance, so an LLNA should not ethically be completed based on animal welfare reasons

Test material

Test material information

Constituent 1

Reference substance name:

Schiff bases, benzylidene, C16-18 (even numbered) and C18-unsaturated alkyl

Molecular formula:

Not applicable - UVCB

IUPAC Name:

Schiff bases, benzylidene, C16-18 (even numbered) and C18-unsaturated alkyl

Constituent 2

Reference substance name:

Benzaldehyde

EC Number:

202-860-4

EC Name:

Benzaldehyde

Cas Number:

100-52-7

Molecular formula:

C7H6O

IUPAC Name:

benzaldehyde

Test material form:

liquid

In vivo test system

Test animals

Species:

guinea pig

Strain:

Hartley

Sex:

male

Details on test animals and environmental conditions:

Prior to use, all animals were acclimated for at least five days. Animals were individually housed in wire mesh suspension cages. The animals were maintained on a 12-hour cycle light controlled room, at a temperature of 64° - 79°F and a relative humidity of 30-70%. The animals were maintained according to the recommendations contained in the National Academy Press 2011: “Guide for the Care and Use of Laboratory Animals.” The animals were supplied Purina Guinea Pig Chow and tap water ad libitum during both acclimation and test periods. Tox Monitor Laboratories has daily access to feed analysis; water analysis from the city of Chicago is on file. There were no contaminants in either the feed or the water that would be expected to affect the outcome of this study.

Study design: in vivo (non-LLNA)

Induction

Route:

epicutaneous, semiocclusive

Vehicle:

unchanged (no vehicle)

Concentration / amount:

0.4ml

Day(s)/duration:

14days

Adequacy of induction:

highest concentration used causing mild-to-moderate skin irritation and well-tolerated systemically

Challenge

No.:

#20

Route:

epicutaneous, semiocclusive

Vehicle:

unchanged (no vehicle)

Concentration / amount:

0.4ml

Day(s)/duration:

24 and 48hrs

Adequacy of challenge:

highest non-irritant concentration

No. of animals per dose:

20 animals

Details on study design:

The day prior to test substance exposure, the hair was removed from each of the animal's backs using a small animal clipper. Closed patches were applied to the animals in the following manner. A 0.4 ml quantity of each test preparation was applied directly into a 25 mm Hilltop Chamber®. The animals were held gently, and the chambers were applied as quickly as possible to the clipped left shoulder. The chambers were secured with Micropore tape and further secured with Kendall adhesive tape. Approximately six hours later, the tape and chambers were removed. The lowest irritating concentration are used for the induction phase and the highest non irritating concentration is used for the challenge phase.

Challenge controls:

10 animals were challenged with 1-chloro-2,4-dinitrobenzene within 6 months of the study to show that the strain of guinea pig could accurately detect skin sensitizers.

Positive control substance(s):

yes

Remarks:

1-chloro-2,4-dinitrobenzene

Results and discussion

In vivo (non-LLNA)

Results

Results 1

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

positive control

Dose level:

2.5%

No. with + reactions:

0

Total no. in group:

20

Clinical observations:

None

Results 2

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

positive control

Dose level:

2.5%

No. with + reactions:

0

Total no. in group:

20

Clinical observations:

None

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Based on the criteria set forth byt the CLP regulation and in accordance to the CLP guidiance, the test substance will not be classified for skin sensitization.

Executive summary:

The test substance was tested for dermal sensitization potential utilizing a Buehler Technique Guinea Pig Sensitization Protocol. The test substance was evaluated for sensitization potential by applying 0.4 ml at a 10% concentration directly into Hilltop Chambers® and applying them to the clipped left shoulder of twenty albino guinea pigs in the following manner: The animals were held gently, and the chambers were applied as quickly as possible to the clipped left shoulder. The chambers were secured with Micropore tape and further secured with Kendall adhesive tape. Approximately six hours later, the tape and chambers were removed. Two additional induction doses were conducted following the same procedure, at weekly intervals. Two weeks after the final application the animals received a topical primary challenge dose (6

hour contact) of Test substance at 2.5% concentration, on a naive site located on the right shoulder. Animals were scored for irritation at 24 and 48 hours after initiation of the primary challenge application. Ten guinea pigs served as a naive control group, and remained untreated through the induction phase. Six naive control animals received only the primary challenge dose, at a 2.5% concentration. The four remaining guinea pigs were designated for a re-challenge, if necessary. Following primary challenge of teast substance at 2.5% concentration, the incidence of grade 1 response or greater in the test group (0 of 20) was compared to that of the naive control group (0 of 6). The incidence and severity of these responses were not significantly greater than those produced by the naive control group indicating that sensitization had not been induced. Therefore based on the criteria set forth byt the CLP regulation and in accordance to the CLP guidiance, the test substance will not be classified for skin sensitization.