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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:
key study
Study period:
1973
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
2008
Report Date:
2008

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
A small quantity of each test substance was placed on the wetted (tap water) central gauze portion of 1 1/2-inch-square BandAid before application to a nonhairy region of the upper back. Strips of Dermicel hypoallergenic tape were used to occlude, cover and secure the patches. The patches were applied to the same areas on Mondays, Wednesdays and Fridays for 3 weeks ( 9 applications in total) for 24 hr and then removed by the subjects themselves, except for the first two occasions when the investigators removed the patches. The subjects did not expose their backs to sunlight during this procedure. Residual powder was gently removed from the skin with the soft alcohol pads. The reactions were graded and recorded during each visit. An additional visit for grading and observation took place on Monday of the 4th week.

Challenge applications were performed on Monday of the 6th week following the commencement of the sensitization procedure. Patches were applied to a previously untested area of the of the upper back skin using the method described above, except that they were left in situ for 48 hr before removal. The reactions were graded shortly after patches removal and then at 96 and 144 hr after application.
Additional 48 hr challenging applications were performed on certain subjects following the same procedures.
GLP compliance:
no
Type of study:
Draize test
Justification for non-LLNA method:
Human study.

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: crystalline

In vivo test system

Test animals

Species:
other: Human
Sex:
not specified

Study design: in vivo (non-LLNA)

Induction
Route:
epicutaneous, occlusive
Vehicle:
other: polystyrene or petrolatum
Concentration / amount:
p-toluic acid, 50% in polystyrene, and o-toluic acid, 50% in polystyrene
Day(s)/duration:
2
Adequacy of induction:
highest concentration used causing mild-to-moderate skin irritation and well-tolerated systemically
Challenge
No.:
#1
Route:
epicutaneous, occlusive
Vehicle:
other: polystyrene powder and petrolatum
Concentration / amount:
p-toluic, o-toluic and m-toluic acids, all three isomers at concentrations of 50% in polystyrene powder, 5% in petrolatum, and 1% in petrolatum.
Day(s)/duration:
4
Adequacy of challenge:
other: Reactions were observed in all 4 subjects to all three isomers,
No. of animals per dose:
4
Details on study design:
RANGE FINDING TESTS:

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 1
- Exposure period: 2 days
- Test groups: 1
- Control group: none
- Site:
- Frequency of applications: once
- Duration:
- Concentrations: 50%

B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day(s) of challenge: 4
- Exposure period: 4
- Test groups: 1
- Control group: none
- Site:
- Concentrations:
- Evaluation (hr after challenge): 18 days

OTHER:
Challenge controls:
none
Positive control substance(s):
no

Results and discussion

Positive control results:
not applicable

In vivo (non-LLNA)

Resultsopen allclose all
Key result
Reading:
1st reading
Hours after challenge:
48
Group:
test group
Dose level:
50%
No. with + reactions:
4
Total no. in group:
10
Clinical observations:
Five of the subjects became sensitized to p-toluic. Sensitization reactions to p-toluic acid occurred days 15-18. In some subjects the challenge reactions were severe and necessitated removal of the patches before completion of 48-hr application time.
Remarks on result:
positive indication of skin sensitisation
Group:
negative control
Remarks on result:
not measured/tested
Group:
positive control
Remarks on result:
not measured/tested

Applicant's summary and conclusion

Interpretation of results:
Category 1 (skin sensitising) based on GHS criteria
Conclusions:
Under the conditions of this study, p-toluic acid was shown to be sensitising to human skin.