Dodecanoic acid, 2,2-dimethyl-3-oxopropyl ester

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2004-11-10 to 2004-12-04

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2004

Report date:

2005

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Version / remarks:

17 July 1992

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2600 (Skin Sensitisation)

Version / remarks:

August 1996

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

EU Method B.6 (Skin Sensitisation)

Version / remarks:

Directive 92/69/EEC

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

The guinea pig maximisation test has been carried out as an animal test to predict human sensitization for over a decade and is recommended by international test guidelines such as OECD.

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

468-880-2

EC Name:

-

Cas Number:

102985-93-3

Molecular formula:

C17H32O3

IUPAC Name:

2,2-dimethyl-3-oxopropyl dodecanoate

Test material form:

liquid

In vivo test system

Test animals

Species:

guinea pig

Strain:

Dunkin-Hartley

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: LAB-ALL Bt. Budapest, 1174 Hunyadi u. 7
- Weight at study initiation: The weight variation in animals involved in the study was not exceed ± 20 % of the mean weight.
- Housing: Animals were housed in macrolon cages, size III., with 3 or 2 animals/cage (42 x 42 x 19 cm).
- Acclimation period: 7 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 ± 3 °C
- Humidity (%): 30 - 70 %
- Air changes (per hr): 8 - 12
- Photoperiod (hrs dark / hrs light): 12 hours daily from 6 a.m. to 6 p.m. (artificial light)

Study design: in vivo (non-LLNA)

Induction

Route:

intradermal and epicutaneous

Vehicle:

other: oleum helianthi

Concentration / amount:

For the intra-dermal application 0.1 mL formulated test item was injected at concentrations of 0.1, 1 and 5% (w/v). The test item was formulated in oleum helianthi. Two different concentrations were applied per animal to the hairless skin on the right and left flanks, and two animals were employed per concentration tested.

For the dermal application 0.5 mL of formulated test item was applied onto the skin of the animals at concentrations of 25, 50, 75% (w/v) in oleum helianthi, and in undiluted state. A closed patch exposure was employed by means of an occlusive bandage. Two animals/ two different concentrations were used.

Challenge

Route:

other: epicutaneous

Vehicle:

other: oleum helianthi

Concentration / amount:

For the intra-dermal application 0.1 mL formulated test item was injected at concentrations of 0.1, 1 and 5% (w/v). The test item was formulated in oleum helianthi. Two different concentrations were applied per animal to the hairless skin on the right and left flanks, and two animals were employed per concentration tested.

For the dermal application 0.5 mL of formulated test item was applied onto the skin of the animals at concentrations of 25, 50, 75% (w/v) in oleum helianthi, and in undiluted state. A closed patch exposure was employed by means of an occlusive bandage. Two animals/ two different concentrations were used.

No. of animals per dose:

Test group: 10 animals
Control group: 5 animals

Details on study design:

RANGE FINDING TESTS:
A series of test item concentrations was tested to identify any primary irritation caused by intra-dermal injection and dermal application. Three dose levels were tested in the preliminary dose range finding study to identify the primary irritation by intra-dermal injection and four dose levels by dermal application.
The test item was applied at concentrations of 0.1,1 and 5 % (w/v) for intradermal injection and 25, 50, 75 % (w/v) and in undiluted state for dermal application.
For the intra-dermal application 0.1 mL formulated test item was injected at concentrations of 0.1, 1 and 5 % (w/v). The test item was formulated in oleum helianthi. Two different concentrations were applied per animal to the hairless skin on the right and left flanks, and two animals were employed per concentration tested. For the dermal application 0.5 mL of formulated test item was applied onto the skin of the animals at concentrations of 25, 50, 75 % (w/v) in oleum helianthi, and in undiluted state. A closed patch exposure was employed by means of an occlusive bandage. Two animals/ two different concentrations were used.

MAIN STUDY
A. INDUCTION EXPOSURE

Main Study I: Intra-dermal Induction Exposure
Before starting the exposure an area of approximately 5x5 cm on the scapular region of animals was clipped free of hair and shaven close with care.
Intra-dermal treatment Test groups:
A row of three injections, six in all, was made on each side of test animals, as follows:
2 injections with 0.1 mL of Freund's complete adjuvant (FCA) mixed with physiological saline solution (1:1),
2 injections with 0.1 mL of the test item (5 %) homogenized in oleum helianthi,
2 injections with 0.1 mL of test item mixed with physiological saline solution and homogenized in Freund's complete adjuvant (5 %).
Control group:
The control animals were treated similarly as the test group however, the vehicle, without the test item was used for injections, as follows:
2 injections with 0.1 mL mix of Freund's complete adjuvant and physiological saline solution (1:1)(v/v),
2 injections with 0.1 mL of oleum helianthi,
2 injections with 0.1 mL of 50 v/v % oleum helianthi in a 1:1 mixture (v/v) of Freund's complete adjuvant and physiological saline solution.

Main study II: Dermal Induction Exposure
Six days after the intra dermal injections, in all animals the test area was painted with 0.5 mL of 10 % sodium lauryl sulphate in vaseline 24 h prior to topical induction application, in order to create a local irritation. Approximately 24 hours after painting, the test animals were exposed to test item and the control animals were treated with oleum helianthi as vehicle.
Closed patch was applied in the following manner: in case of the test animals 0.50ml of test item (in undiluted state) was spread on the surface prepared previously and covered with a standard (5x5 cm) size of porous gauze patch. The sample was secured by a piece of PVC tape and occluded with adhesive bandage. Control animals were treated dermally with 0.50 mL of oleum helianthi as vehicle and the dressing was prepared and applied as for the test animals.
The patches were left in place for 48 hours. At the end of exposure the bandage was removed and the excess material was wiped off.
Following the dermal induction treatment the animals were left untreated for 14 days prior to challenge.

B. CHALLENGE EXPOSURE

Main study III: Challenge Exposure
Two weeks after the dermal treatment the animals were exposed to the challenge dose, dermally. 24 hours before the challenge treatment the left and the right flank areas (5x5 cm) of each animal were prepared for application. The challenge was performed as a dermal exposure (Closed Patch Test). Left shaved flank areas of the animals (both the test and the control) were treated with 0.50 mL of the test item (in undiluted state). The right shaved flank areas were treated with 0.50 mL of oleum helianthi, in all cases. Time of exposure was 24 hours.

Positive control substance(s):

no

Results and discussion

In vivo (non-LLNA)

Results

Results 1

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

100 %

No. with + reactions:

0

Total no. in group:

5

Clinical observations:

none

Results 2

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

100 %

No. with + reactions:

0

Total no. in group:

5

Clinical observations:

none

Results 3

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

100 %

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

none

Results 4

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

100 %

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

none

Results 5

Reading:

1st reading

Hours after challenge:

24

Group:

positive control

Dose level:

100 %

No. with + reactions:

0

Total no. in group:

0

Clinical observations:

none

Remarks on result:

not measured/tested

Results 6

Reading:

2nd reading

Hours after challenge:

48

Group:

positive control

Dose level:

100 %

No. with + reactions:

0

Total no. in group:

0

Clinical observations:

none

Remarks on result:

not measured/tested

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Challenge with the test item 2,2-Dimethyl-3-lauroyloxy-propanal evoked no positive responses in the test animals previously sensitised. At the same time, none of the animals proved to be positive in the control group. The net response value represented a sensitisation rate of 0 % as no indication for adverse skin reactions were noted (mean of scores was 0.00). Based on the results of the present study, the test item 2,2-Dimethyl-3-lauroyloxy-propanal was classified as non- sensitiser.

Executive summary:

A skin sensitisation study was performed according to Magnusson-Kligman method using Freund's complete adjuvant technique to evaluate the sensitisation potential of test item 2,2-Dimethyl-3-lauroyloxy-propanal. 10 test animals were subjected to sensitisation procedures in a two-stage operation, i.e. an intra-dermal treatment and a topical application. The test item was used at the concentration of 5 % for intra-dermal injections and in undiluted state for dermal sensitisation treatment. The test area was painted with 0.5 mL of 10% sodium lauryl sulphate in vaseline 24 h prior to the topical induction application, in order to create a local irritation. Two weeks following the last induction exposure, a challenge dose (in undiluted state) was administered. Challenge was performed by dermal application of the test item. 5 control guinea pigs were simultaneously exposed to the vehicle during the sensitisation phase and they were treated with the test item (in undiluted state) in the case of challenge. No signs of contact sensitisation in guinea pigs were noted after the challenge phase. In the control and treated animals no reactions at all were observed and the mean of the scores was 0.00 according to the results of the 24th and 48th-hour readings.