Registration Dossier

Administrative data

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
24 July 1991 to 31 August 1991
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Proprietary GLP study, comparable to guidelines.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1991
Report Date:
1991

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Deviations:
no
GLP compliance:
yes
Type of study:
Buehler test

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Test material form:
solid: particulate/powder
Remarks:
migrated information: powder
Details on test material:
- Name of test material (as cited in study report): Isophthalic acid 220
- Substance type: Organic acid
- Physical state: White powder
- Identification no: ATTA 91-30(TA 313C)
The test material was stored at room temperature (approximately 22°C), the sponsor indicated that the test material was stable under these conditions.

In vivo test system

Test animals

Species:
guinea pig
Strain:
Hartley
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Murphy Breeding laboratories, Plainfield, IN, USA
- Age at study initiation: 9 weeks of age
- Weight at study initiation: Weight at arrival was 281-370 g
- Fasting period before study: Not stated
- Housing: Housed individually in stainless steel cages measuring 24.9 x 17.8 x 39.8 cm. Polyzorb pads were placed in the pan below the stainles steel mesh of each animals cage to absorb liquids.
- Diet (e.g. ad libitum): Guinea Pigs Chow 5025 (Ralston Purina Co., St. Louis, MO, USA) ad libitum
- Water (e.g. ad libitum): Purified water ad libitum
- Acclimation period: 3 weeks


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22
- Humidity (%): 63
- Air changes (per hr): Not stated
- Photoperiod (hrs dark / hrs light): 12/12

Study design: in vivo (non-LLNA)

Inductionopen allclose all
Route:
epicutaneous, occlusive
Vehicle:
DMSO
Concentration / amount:
The test article was prepared as a 30% (w/w) solution in DMSO, and 0.3 mL was applied for the induction phase.
Challengeopen allclose all
Route:
epicutaneous, occlusive
Vehicle:
DMSO
Concentration / amount:
The test article was prepared as a 30% (w/w) solution in DMSO, and 0.3 mL was applied for the induction phase.
No. of animals per dose:
10e.
Details on study design:
The test article was prepared as a 30% (w/w) solution in DMSO. Solutions were prepared fresh for each induction and challenge dose.
Undiluted DMSO was applied to the vehicle control guinea pigs during the induction phase. A 70% (w/w) solution of DMSO in reverse osmosis-purifed water was prepared and applied to the vehicle control guinea pigs for the challenge dose.

Induction: Using a Hill Top Chamber, 0.3 ml of the 30% test article/DMSO solution, or undiluted DMSO was applied to the upper left quadrant of the backs of the ten guinea pigs in the treated and control groups respectively, once/week for a period of three weeks. Elastoplast was wrapped around the midsection of the guinea pigs to keep the Hill Top Chamber in place. All wrapping materials were removed 6 hours after each application. The 10 control guinea pigs were handled in the same manner (without the addition of isophthalic acid to the chamber).

Challenge: Two weeks following application of the last induction dose, 0.3 ml of the 30% test article/DMSO solution was applied to the lower left quadrant of the backs of the 10 treated guinea pigs. Challenge control guinea pigs also received a challenge dose of 0.3 ml of the 30% test article/DMSO solution. Vehicle control guinea pigs each received a challenge dose of 0.3 ml of a 70% aqueous DMSO solution. The challenge dose for all sham and control guinea pigs was applied at the same site as the treated guinea pigs (lower left quadrant). The test materials were applied in an identical manner to that used in the induction phase, all wrappings were removed 6 hours after the challenge application.

Approximately 24 and 48 hours after application of the first induction dose and of the challenge dose, the test sites were scored for erythema according to the Draize method. To facilitate scoring, all animals were shaved immediately prior to scoring during the induction phase, while all of the guinea pigs were depilated with Neet Hair Remover approximately 2 hours prior to the 24 hour scoring during the challenge phase.
All guinea pigs were observed daily for mortality and morbidity. Body weights were measured weekly. Necropsies were not performed.
Challenge controls:
Yes - guinea pigs that received repeated applications of undiluted DMSO in the induction phase were challenged with 30% (w/w) test article/DMSO solution.
Positive control substance(s):
no

Study design: in vivo (LLNA)

Statistics:
Two -factor log-linear models were used to assess the effects of treatment (treatment vs. sham control, treatmed vs. vehicle control and vehicle vs. sham control) and time saving (24 hr vs. 48 hr) on erythema reactions. For the purpose of the interpretation, the log-linear model is an analogue of the analysis of variance procedures where the qualitative response, such as a rating scale of erythema, was the focus of the investigation.

A Chi-square statistic was generated to test the significance of the overall treatment vs. control differences and the combination of treatment and time scoring. The statistical analyses were performed using SYSTAT.

Results and discussion

Positive control results:
A positive control was not included in this study.

In vivo (non-LLNA)

Results
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
0.3 ml of 30% solution in DMSO
No. with + reactions:
1
Total no. in group:
10
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 0.3 ml of 30% solution in DMSO. No with. + reactions: 1.0. Total no. in groups: 10.0.

Any other information on results incl. tables

Summation of individual erythema scores

Time of scoring after challenge Dose.

 

24 hours

48 hours

Group 

Erythema score

Erythema score

0

1

2

3

4

0

1

2

3

4

Treated

2

7

1

0

0

3

7

0

0

0

Vehicle Control

3

7

0

0

0

8

2

0

0

0

Sham Control

3

7

0

0

0

4

6

0

0

0

Applicant's summary and conclusion

Interpretation of results:
not sensitising
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
No evidence of sensitisation was seen under the conditions of this study.
Executive summary:

In a Buehler study, isophthalic acid was applied once a week at a dose of 0.3 ml of a 30% (w/w) solution in dimethyl sulfoxide (DMSO) to the shaved backs of ten male guinea pigs during an induction period of three weeks. Another group of 10 male guinea pigs served as a vehicle control and was similarly dosed with 0.3 ml of undiluted DMSO. A third group of ten sham control guinea pigs was handled in the same manner, but was not treated with the test article. Two weeks following application of the third induction dose, the treated and sham control guinea pigs each received a challenge dose of 0.3 ml of the 30% (w/w) test article/DMSO solution; the vehicle control guinea pigs each received a challenge dose of 0.3 ml of a 70% (w/w) aqueous DMSO solution. All guinea pigs were scored for erythema approximately 24 and 48 hours following application of the first dose and the challenge dose.

A positive erythema reaction (score greater than or equal to 2) was observed in one test article-treated guinea pig during the challenge phase of the study. Positive erythema reactions were not observed in any vehicle or sham control guinea pigs after challenge.

Based on the statistical analyses, neither the primary effect of treatment with isophthalic acid nor the secondary effect of time of scoring was a significant factor; the effect of treatment for the vehicle versus sham control comparison was also not significant. These results indicate that sensitization was not induced in guinea pigs following repeated dermal application of isophthalic acid.