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Toxicological information

Skin sensitisation

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Administrative data

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
1973
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
other: Older human volunteer study, reporting is very brief. The study was conducted prior to development of GLP and current test guidelines.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1973
Report Date:
1973

Materials and methods

Test guideline
Qualifier:
no guideline available
Principles of method if other than guideline:
The study was a patch test conducted in human volunteers, and was conducted prior to development of current guidelines. A preliminary irritation screen was performed, followed by a maximisation test.
GLP compliance:
no
Remarks:
Conducted prior to development of GLP
Type of study:
patch test
Justification for non-LLNA method:
Other study data available which together justify a WOE approach.

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
not specified
Details on test material:
- Name of test material (as cited in study report): RIFM 72-4-168 Isobutyl phenylacetate

In vivo test system

Test animals

Species:
human
Strain:
other: N/a
Sex:
male
Details on test animals and environmental conditions:
Twenty five healthy adult males, aged between 22 and 62 years.

Study design: in vivo (non-LLNA)

Induction
Route:
epicutaneous, occlusive
Vehicle:
no data
Concentration / amount:
No further information provided (it is assumed the test substance was applied undiluted).
Challenge
Route:
epicutaneous, occlusive
Vehicle:
no data
Concentration / amount:
No further information provided (it is assumed the test substance was applied undiluted).
No. of animals per dose:
25 (total)
Details on study design:
Pre-testing:
A preliminary irritation screen was conducted on five subjects in order to determine whether sodium lauryl sulfate pre-treatment was required. A patch of the test substance was applied to normal sites on the back for 48 hours under occlusion. The sites were assessed for any reactions.

Maximisation test:
The test substance was applied under occlusion to the same sites on the volar forearms on all subjects for five alternate-day, 48-hour exposure periods. Each test application was preceded by 24 hour occlusive pre-treatment of the patch site with 5% aqueous sodium lauryl sulfate. Following a ten day rest period, challenge patches were preceded by one hour pretreatment with 10% aqueous sodium lauryl sulfate. The challenge sites were evaluated for signs of reactions on removal of patches and 24 hours thereafter.
Challenge controls:
No controls.
Positive control substance(s):
not required

Results and discussion

Positive control results:
Not applicable - no positive control

In vivo (non-LLNA)

Resultsopen allclose all
Reading:
1st reading
Hours after challenge:
48
Group:
test group
No. with + reactions:
0
Total no. in group:
25
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 48.0. Group: test group. No with. + reactions: 0.0. Total no. in groups: 25.0.
Reading:
2nd reading
Hours after challenge:
72
Group:
test group
No. with + reactions:
0
Total no. in group:
25
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 72.0. Group: test group. No with. + reactions: 0.0. Total no. in groups: 25.0.

Any other information on results incl. tables

Results:

Subject no.

Age

Race

Challenge

48 Hours

72 Hours

1.      

24

B

0

0

2.      

27

B

0

0

3.      

40

B

0

0

4.      

22

B

0

0

5.      

23

B

0

0

6.      

32

B

0

0

7.      

22

B

0

0

8.      

36

B

0

0

9.      

28

B

0

0

10.  

28

B

0

0

11.  

39

B

0

0

12.  

22

B

0

0

13.  

31

B

0

0

14.  

46

B

0

0

15.  

49

B

0

0

16.  

25

B

0

0

17.  

62

B

0

0

18.  

39

B

0

0

19.  

23

B

0

0

20.  

23

B

0

0

21.  

25

B

0

0

22.  

25

B

0

0

23.  

30

B

0

0

24.  

24

B

0

0

25.  

24

B

0

0

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
No skin reactions were observed following the challenge application.
Executive summary:

The sensitising potential of isobutyl phenylacetate was evaluated in a human volunteer study. Initially, a preliminary irritation screen was conducted in 5 male subjects: the test substance was applied to the back skin under an occlusive patch for 48 hours. No reactions were observed, therefore a maximisation test was conducted in 25 healthy adult males. The test substance was applied to the same test site on the volar forearm on all subjects under an occlusive patch for five alternate-day, 48-hour periods. Each test application was preceded by a 24 hour occlusive pre-treatment of the test site with 5% aqueous sodium lauryl sulfate. Following a ten-day rest period, challenge applications were made (under an occlusive patch) to a fresh test site for 48 hours. Challenge applications were preceded by a 1-hour pre-treatment with 10% aqueous sodium lauryl sulfate. The challenge sites were evaluated for signs of reactions at patch removal, and again 24 hours later. There were no reactions to challenge in any of the test subjects. It can be concluded that under the conditions of the human volunteer study, the test substance was not sensitising.