Oleic acid, compound with 2-amino-2-methylpropan-1-ol (1:1)

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

17th May 2017- 16th June 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

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Deviations:

no

GLP compliance:

yes

Type of study:

Buehler test

Justification for non-LLNA method:

LLNA frequently gives false positives for irritating substances therefore Buehler test was used. The testing will also be submitted to other regulatory agencies that do not accept LLNA testing.

Test material

Test material information

Constituent 1

Reference substance name:

Oleic acid, compound with 2-amino-2-methylpropan-1-ol (1:1)

EC Number:

268-793-8

EC Name:

Oleic acid, compound with 2-amino-2-methylpropan-1-ol (1:1)

Cas Number:

68140-41-0

Molecular formula:

C18H34O2.C4H11NO

IUPAC Name:

oleic acid, compound with 2-amino-2-methylpropan-1-ol (1:1)

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:

water

Remarks:

Deionised

Concentration / amount:

0.4ml of neat test substance

Day(s)/duration:

6 hourss exposure

Adequacy of induction:

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

Challenge

No.:

#20

Route:

epicutaneous, semiocclusive

Vehicle:

water

Remarks:

Deionised

Concentration / amount:

0.4ml of 50% concentrration of test substance.

Day(s)/duration:

6 hours

Adequacy of challenge:

highest non-irritant concentration

No. of animals per dose:

20 animals induction and challenge

Details on study design:

An irritation screening study was conducted to dertermine the appropriate concentrations to be used for induction and challenge phases. 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 remove. Based upon the irritation screen results the test substance was dosed as 100% concentration for
the induction phase of the study, and 50% concentration, the highest non-irritating concentration, for the challenge phase of the study.


The induction phase was then conducted to dermally expose the animal to test substance so that if the test substance is a sensitizer, the physiological process required to ultimately allow the generation of an immunological response can be initiated. The left shoulder of each test animal was clipped with a small animal clipper the day before exposure. The animals were held gently and the chambers were applied as previously described under the "Irritation Screening".After the last induction exposure, the animals were left untreated for two weeks (14 days) before primary challenge

The Primary challenge phase was conducted to investigate the elicitation of response to test substance The test animals, which had three previous exposures to the test substance at appropriate intervals, were exposed to the test substance in the challenge phase fourteen days after the last induction exposure. The same exposure procedure as for the "Induction Phase" was used, except the Hilltop Chambers were applied to a skin site that had not been previously exposed. Each animal received a single chamber of the test substance. The day following the primary challenge exposure all animals were scored.

Challenge controls:

6 animals were used as negative control and 4 were kept for rechallenge.

Positive control substance(s):

yes

Results and discussion

In vivo (non-LLNA)

Results

Results 1

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

50%

No. with + reactions:

0

Total no. in group:

20

Remarks on result:

no indication of skin sensitisation

Results 2

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

50%

No. with + reactions:

0

Total no. in group:

20

Remarks on result:

no indication of skin sensitisation

Results 3

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

50%

No. with + reactions:

0

Total no. in group:

6

Remarks on result:

no indication of skin sensitisation

Results 4

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

50%

No. with + reactions:

0

Total no. in group:

6

Remarks on result:

no indication of skin sensitisation

Results 5

Group:

positive control

Remarks on result:

not measured/tested

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Following primary challenge of test substance, at 50% 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, in accordance with the CLP guidance, the test substance does not meet the classification criteria 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 100% 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 50% 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 50% concentration. The four remaining guinea pigs were designated for a re-challenge, if necessary.

Following primary challenge of test substance,  at 50% 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, in accordance with the CLP guidance, the test substance does not meet the classification criteria for skin sensitization.

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