Registration Dossier

Administrative data

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
30 days
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP study conducted according to EPA OPP 81-6 guideline for a skin sensitization study.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1997
Report Date:
1997

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
EPA OPP 81-6 (Skin Sensitisation)
Deviations:
not specified
GLP compliance:
yes
Type of study:
Buehler test
Justification for non-LLNA method:
Study pre-dates original LLNA guideline (OECD 429), adopted in 2002.

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Details on test material:
-Name of test material (as cited in study report): tert-butyl acetate
-Appearance: clear, colorless liquid
-Date received: 7/14/97
-Source: Arco Chemical Company (now LyondellBasell Industries)
-Storage Conditions: room temperature and humidity
-Purity: not reported; used as received

In vivo test system

Test animals

Species:
guinea pig
Strain:
Hartley
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS:
-Source: Ace Animals, Boyertown, PA (received on 7/15/97)
-Animals: 15 males; 10 in Group 1 (test) and 5 in Group 2 (control)
-Age: young adults (born the week of 6/19/97)
-Quarantine period: at least 5 days
-Weight at Study Initiation: 316 - 365 g
-Housing: 1/cage in suspended wire-mesh cages
-Bedding: placed beneath the cages and changed at least 3x/week
-Diet: Purina® Guinea Pig Chow® Diet # 5025; ad libitum
-Water: ad libitum
-Identification method: uniquely numbered metal ear tag
-Method of Animal Distribution: no data

ENVIRONMENTAL CONDITIONS:
-Room temperature: controlled
-Light: 12 hour light/dark cycle

IN-LIFE DATES:
-Date of study initiation: 7/21/97
-Date of study termination: 8/21/97

Study design: in vivo (non-LLNA)

Inductionopen allclose all
Route:
epicutaneous, occlusive
Vehicle:
unchanged (no vehicle)
Concentration / amount:
100%
Challengeopen allclose all
Route:
epicutaneous, occlusive
Vehicle:
unchanged (no vehicle)
Concentration / amount:
100%
No. of animals per dose:
Ten males (Group 1) received the test substance at a concentration of 100%. Five males (Group 2) were not induced with the test substance and served as naïve controls.
Details on study design:
MB Research Protocol used: 112-03; there were no amendments to the protocol. EPA 40 CFR 158.340, Guideline Reference #81-6

Based on the results of the topical induction applications, 100% was chosen as the highest non-irritating concentration to be used during the topical challenge phase of the study.

-Site preparation: On the day prior to the first induction application, the left dorsal area (Site 1 - approximately 5 x 10 cm) of each guinea pig in the test group was clipped free of hair. The treated sites were reclipped the day prior to each induction application. Thirteen days after the last induction application, a naïve site (Site 3 - left hip area) on each animal was clipped free of hair. Sites 1 and 3 were reserved for induction and challenge application and Sites 2 and 4 (right shoulder and hip) were to be used in the event of eschar formation or if a need to rechallenge the animals arose.

-Induction phase: For each guinea pig in the test group, a dose of 0.4 mL of the test material was applied to the left shoulder area (Site 1) using a 25 mm Hilltop Chamber. The chamber was covered with a 8 x 8 cm piece of rubber dental dam and wrapped with non-irritating tape to provide occlusion. After 6 hours, the dams were removed and any residual test material was removed with distilled water. The induction procedure was performed on the same day each week for a period of three weeks. The five animals in the control group were untreated for the three week induction phase and served as naïve controls.

-Challenge phase: Fourteen days after the last induction application, all animals (treated and control) were challenged (Site 3) with a dose of 0.4 mL of a 100% concentration of the test material using the same dosing procedure as the induction phase.

-Observations: The application sites of animals in the treated group were examined and scored at 24 and 48 hours after each induction. The challenge sites of both test and control animals were examined and scored at 24, 48, and 72 hours after the challenge application. Animals were observed once a day for mortality and any abnormal effects.

-Body weights: Weights were recorded pretest, the day following the last induction, and the day following the challenge application.
Challenge controls:
Five guinea pigs were not induced with the test substance during the induction phase and served as a naïve control group. The control group was challenged with the test substance using the same procedure as in the treated group.
Positive control substance(s):
yes
Remarks:
DNCB (dinitrochlorobenzene)

Results and discussion

Positive control results:
A previous study using DNCB (dinitrochlorobenzene) was used as a historical positive control. The DNCB study produced a positive sensitization response in the same strain of guinea pigs purchased from the same supplier.

In vivo (non-LLNA)

Resultsopen allclose all
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
100%
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
After the challenge application, only one of the ten animals displayed a very faint erythema (Grade of 0.5 - not considered a positive score) at the 24-hour examinations.
Remarks on result:
other: see Remark
Remarks:
Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 100%. No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: After the challenge application, only one of the ten animals displayed a very faint erythema (Grade of 0.5 - not considered a positive score) at the 24-hour examinations..
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
100%
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
At the 48-hour examinations, all challenge sites appeared normal.
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: 10.0. Clinical observations: At the 48-hour examinations, all challenge sites appeared normal. .
Reading:
other: 3rd reading
Hours after challenge:
72
Group:
test group
Dose level:
100%
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
At the 72-hour examinations, all challenge sites appeared normal.
Remarks on result:
other: Reading:
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
100%
No. with + reactions:
0
Total no. in group:
5
Clinical observations:
After the challenge application, all treated sites appeared normal at the 24-hour examinations.
Remarks on result:
other: see Remark
Remarks:
Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: 100%. No with. + reactions: 0.0. Total no. in groups: 5.0. Clinical observations: After the challenge application, all treated sites appeared normal at the 24-hour examinations..
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
100%
No. with + reactions:
0
Total no. in group:
5
Clinical observations:
After the challenge application, all treated sites appeared normal at the 48-hour examinations.
Remarks on result:
other: see Remark
Remarks:
Reading: 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 100%. No with. + reactions: 0.0. Total no. in groups: 5.0. Clinical observations: After the challenge application, all treated sites appeared normal at the 48-hour examinations..
Reading:
other: 3rd reading
Hours after challenge:
72
Group:
negative control
Dose level:
100%
No. with + reactions:
0
Total no. in group:
5
Clinical observations:
After the challenge application, all treated sites appeared normal at the 72-hour examinations.
Remarks on result:
other: see Remark
Remarks:
Reading: other: 3rd reading. . Hours after challenge: 72.0. Group: negative control. Dose level: 100%. No with. + reactions: 0.0. Total no. in groups: 5.0. Clinical observations: After the challenge application, all treated sites appeared normal at the 72-hour examinations..

Applicant's summary and conclusion

Interpretation of results:
not sensitising
Remarks:
Migrated information
Conclusions:
Tertiary butyl acetate did not produce a positive response in male guinea pigs when the undiluted test material was tested using the Buehler test method. Body weight changes during the study were normal. Except for diarrhea on Days 7 and 8 in a single animal, all animals appeared normal during the observation period.

Based on an absence of positive effects in this study, tertiary butyl acetate is not classifiable for Skin Sensitization according to Directive 67/548/EEC, the UN Globally Harmonized System of Classification and Labelling of Chemicals (GHS) or the EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008.
Executive summary:

In a skin sensitization study using the Buehler test method, 10 guinea pigs were each induced with 0.4 mL of a 100% concentration of tertiary butyl acetate on the clipped skin for a 6 hour exposure.  The procedure was performed weekly for three weeks. Fourteen days after the last induction application, both test and control animals received a topical challenge of 0.4 mL of a 100% concentration of tertiary butyl acetate. Skin examinations at 24, 48, and 72 hours after the challenge dose indicated no positive sensitization reactions in treated or control animals. Tertiary butyl acetate is not considered a skin sensitizer in this study.