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Skin sensitisation

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Administrative data

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
9 Dec 1982 - 8 Jan 1983
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
comparable to guideline study

Data source

Referenceopen allclose all

Reference Type:
study report
Title:
Unnamed
Year:
1983
Report date:
1983
Reference Type:
publication
Title:
The sensitizing potential of primary Amyl Acetate in the guinea pig
Author:
Ballantyne, B. et al.:
Year:
1986
Bibliographic source:
Vet. Hum. Toxicol. 28(3), 213-215

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Principles of method if other than guideline:
Procedures based on the method described by Bertil Magnusson, M.D., and Albert M. Kligman, M.D. Ph.D. in "The Identification of Contact Allergens by Animal Assay: The Guinea Pig Maximization Test," Journal of Investigative Dermatology, 57, 268-276 and in Allergic Contact Dermatitis in the Guinea Pig, Identification of Contact Allergens, Thomas, Springfield, Illinois, 1970.
GLP compliance:
no
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
Study performed before LLNA guideline was available.

Test material

Constituent 1
Chemical structure
Reference substance name:
Reaction mass of 2-methylbutyl acetate and pentyl acetate
EC Number:
908-918-1
Molecular formula:
Unspecified
IUPAC Name:
Reaction mass of 2-methylbutyl acetate and pentyl acetate
Details on test material:
Primary Amyl Acetate (mixture of n-pentyl acetate and 2-methylbutyl acetate)
Test material obtained from Union Carbide Corporation was used. No further information provided other than the test material was a clear, colorless liquid.

In vivo test system

Test animals

Species:
guinea pig
Strain:
Hartley
Sex:
male/female
Details on test animals and environmental conditions:
Supplier: Hazleton-Dutchland, Inc., Denver, Pennsylvania
Date Received: December 1, 1982
Weight Range at Initiation of Treatment (grams): Males: 300-361 Females: 289-341
Animal Identification: Each animal was identified with a monel ear tag bearing its unique animal number.
Selection: Animals were selected randomly for study. Those of questionable health or with outlying body weights were eliminated prior to selection.

Husbandry:
Equilibration Period: 14 days
Housing: Individually in suspended stainless steel cages.
Food: Charles River Vitamin C-Fortified Guinea Pig Diet, -ad libitum.
Water: Automatic watering system, ad libitum (Elizabethtown Water Company).
Environmental Condition: 1. Temperature: 65-75F is considered an acceptable temperature range for guinea pigs; room temperature was monitored twice daily and maintained within this range to the maximum extent possible.
2. Humidity: 30-70% is considered an acceptable humidity range for guinea pigs; humidity was monitored twice daily and maintained within this range to the maximum extent possibl e.
3. Light Cycle: 12 hours light, 12 hours dark (controlled by an automatic timer).

Study design: in vivo (non-LLNA)

Induction
Route:
intradermal and epicutaneous
Vehicle:
unchanged (no vehicle)
Concentration / amount:
1. Induction (Intradermal):
Site One:
Adjuvant: 10 mls of FCA was added to 10 mls deionized water, to produce a 0.5 g/ml (50%) mixture.
Site Two: Test or control material
Vehicle Control: 100% - Primary Amyl Acetate (no mixture required)
Positive Control: 0.01 g of DNCB was added to 10 mls propylene glycol to produce a 0.001 g/ml (0.1 %) mixture.

2. Topical:
Vehicle Control: Primary Amyl Acetate - 100% (no mixture required) for induction and challenge phase.
Positive Control:
Induction: 0.01 g of.DNCB was added to 80% ethanol which was brought to a total volume of 10 ml to produce a 0.001 g/ml (0.1%) mixture.
Challenge: 0.01 g of DNCB was added to 80% ethanol which was brought to a total volume of 10 ml to produce a 0.001 g/ml 0.1%) mixture.

Fresh mixtures were prepared prior to each administration.
Challenge
No.:
#1
Route:
epicutaneous, semiocclusive
Vehicle:
unchanged (no vehicle)
Concentration / amount:
Vehicle Control: Primary Amyl Acetate - 100% (no mixture required) for induction and challenge phase.
Positive Control:
Induction: 0.01 g of.DNCB was added to 80% ethanol which was brought to a total volume of 10 ml to produce a 0.001 g/ml (0.1%) mixture.
Challenge: 0.01 g of DNCB was added to 80% ethanol which was brought to a total volume of 10 ml to produce a 0.001 g/ml 0.1%) mixture.

Fresh mixtures were prepared prior to each administration.
No. of animals per dose:
DNCB (Positive control) 10 guinea pigs (5M, 5F)
DNCB (Irritation control) 10 guinea pigs (5M, 5F)

Primary amy acetate 20 guinea pigs (10M, 10F)
Primary amy acetate (irritation control 10 guinea pigs (5M, 5F)
Details on study design:
Dosing Procedure:
1. Induction Phase:
On the day prior to the injections, the hair in the shoulder region (approximately 4x6 cm) was clipped short with an electric clipper. Substances were then administered by intradermal injection, using a 1.0 cc syringe and a 25/26 gauge needle, in the clipped shoulder area. A row of three injections were made on each side, for a total of six injections. The injections consisted of the following :
Two sites with 0.1 ml of FCA/water emulsion
Two sites with 0.1 ml of test or control material
Two sites with 0.1 ml of test or control material/FCA emulsion

2. Induction Phase - Topical Application:
One week after the intradermal injections, the topical application was performed. The hair in the shoulder area was re-clipped.

The vehicle (Primary Amyl Acetate) without the test substance, and the positive control material was applied to control animals in the same manner as the test substance. The patches were left in place for 48 hours after which they were removed and the skin wiped free of any excess material.

3. Challenge Phase:
Two weeks after the topical application, the challege treatment was administered. The hair was removed from a 5x5 cm area on the flank, by clipping as described previously.
Patches were applied to the flanks using the same procedure as for topical application on Day 7, except that a 2x2 cm piece of filter paper was used and allowed to remain on the animal for 24 hours.

4. Irritation Control Challenge:
In order to differentiate dermal reactions produced by irritation from those produced by sensitization, ten animals (previously untreated) were subjected to the same challenge procedures as the animals which were dosed during the induction phase.

Experimental Evaluation:
Viability Check: Twice Daily
Observations: Animals were observed prior to treatment and weekly during the study for general health and unusual observations were recorded. (Animals which were not considered to be in good health prior to treatment were not placed on study) .
Evaluation of Dermal Responses:
Approximately 21 hours a:fter removing the patch, the challenge area was gently clipped. Readings were made on all animals 24 and 48 hours after the removal of the patches.

At each interval the treated site was evaluated for erythema and edema or other evidence of dermal irritation according to the scoring system used. Adjacent areas of untreated skin was used for comparison. Special notations were made of necrosis, eschar, or other evidence of irreversibi l e alteration of tissue structure. Any abnormal pharmacologic signs were also noted.

Redness or edema at the challenge site at any of the observations which was greater than that seen in the vehicle and/or irritation control animal s was considered an allergic response. Number (percentages) of animals reacting, rather than intensity of reactions, is the criterion for categorizing materials as sensitizers and assessing sensitization potency.

Sensitizers are categorized, based on percentage of animals affected as weak (Grade 1) to extreme (Grade V) sensitizers.
Challenge controls:
See above
Positive control substance(s):
yes
Remarks:
2,4-dinitrochlorohenzene (DNCB)

Study design: in vivo (LLNA)

Positive control substance(s):
other: 2,4-dinitrochlorobenzene
Statistics:
No additional information available.

Results and discussion

Positive control results:
All of the ten animals treated with DNCB (Group 1A ) exhibited dermal responses at challenge to a non-irritating concentration, as confirmed by a lack of response by control animals (Group IB) to the same concentration. This positive response to a known sensitizer demonstrates the susceptibility of this group of animals to sensitization.

In vivo (non-LLNA)

Resultsopen allclose all
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
100 %
No. with + reactions:
1
Total no. in group:
20
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 100 %. No with. + reactions: 1.0. Total no. in groups: 20.0.
Reading:
2nd reading
Hours after challenge:
48
Group:
test chemical
Dose level:
100 %
No. with + reactions:
0
Total no. in group:
20
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 100 %. No with. + reactions: 0.0. Total no. in groups: 20.0.
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
0.1 %
No. with + reactions:
10
Total no. in group:
10
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: positive control. Dose level: 0.1 %. No with. + reactions: 10.0. Total no. in groups: 10.0.
Reading:
2nd reading
Hours after challenge:
48
Group:
positive control
Dose level:
0.1 %
No. with + reactions:
9
Total no. in group:
10
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: positive control. Dose level: 0.1 %. No with. + reactions: 9.0. Total no. in groups: 10.0.

Any other information on results incl. tables

Mortality

All animals survived throughout the study.

Dermal Responses

Dermal scores of 1 or greater (in the absence of dermal response in irritation control animals) are considered clearly indicative of sensitization. Scores of + (barely perceptible erythema) are considered equivocal, although a high percentage of scores o f + in treated animals with no dermal response in irritation control animals is considered suggestive of sensitization.

Several (17 of 20) of the animals treated with primary amyl acetate (Group IIA) exhibited barely perceptible erythema (scores of +) at 24 hours, one exhibited a dermal score of 1, and 4 exhibited edema. However, 5 of the 10 irritation control animals (Group IIB) also exhibited slight dermal erythema (scores of 2 or 1) at 24 hours. At 48 hours, only two test animals had minimal erythema (scores o f +) and no responses were present in irritation control animals. Although it is possible that this material may possess a very slight sensitization potential, the response seen is considered more indicative of transient irritation than of sensitization.

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met