Pyrocatechol

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Remarks:

It is a study on derivatives of catechol. In this study, Catechol was used as inducer for sensitization. Lack of details in results.

Data source

Reference

Reference Type:

publication

Title:

Delayed contact to catechols. III. The Relationship of Side-Chain Length to Sensitizing Potency of Catechols Chemically Related to the Active Principles of Poison Ivy.

Author:

Baer H., Watkins R.C., Kurts A.P., Byck J.S., Dawson C.R.

Year:

1967

Bibliographic source:

The Journal of Immunology, 99(2), 370-375.

Materials and methods

Test guideline

Guideline:

other: Freund's complete adjuvant test

GLP compliance:

no

Type of study:

Freund's complete adjuvant test

Justification for non-LLNA method:

An appropriate guinea pig Freund's complete adjuvant test is available which would not justify conducting an additional LLNA due to animal welfare. In addition, this study predates the adoption of the Local Lymph Node Assay (LLNA; TG 429).

Test material

Test material information

Constituent 1

Reference substance name:

Pyrocatechol

EC Number:

204-427-5

EC Name:

Pyrocatechol

Cas Number:

120-80-9

Molecular formula:

C6H6O2

IUPAC Name:

pyrocatechol

Details on test material:

no data

In vivo test system

Test animals

Species:

guinea pig

Strain:

Hartley

Sex:

male

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: from the National Institutes of Health Animal Production section.
- Age at study initiation:
- Weight at study initiation: approx. 400 g
No more data.

Study design: in vivo (non-LLNA)

Induction

Induction 1

Route:

intradermal

Vehicle:

other: emulsion

Induction 2

Concentration / amount:

1 mL (combined volume of the three injections)

Challenge

Challenge 1

Route:

epicutaneous, semiocclusive

Vehicle:

other: emulsion

Challenge 2

Concentration / amount:

1 ml (combined volume of the three injections)

No. of animals per dose:

8 to 12 animals.

Details on study design:

- Sensitisation was carried out by injection of an emulsion in complete Freund's adjuvant, at weekly intervals, successively into the nuchal area, the inguinal-axillary region and the foot pads. 
- The combined volume of the three injections was 1 ml. The emulsion was prepared from an oil phase containing Drakeol 6VR and Arlacel A (65:35), Mycobacterium butyricum (dried, Difco), Catechol (2 mg/ml) and an equal volume of phophate buffered saline (PBS).
- Thus, 1 mg of catechol was injected into each animal, that was determined in previous study as the dose inducing maximal sensitisation.
- Animals were given a skin test (topical application of catechol in acetone) 4 weeks after the last sensitising injection and then given two repetitive tests at 2-weeks intervals.
- The end point is the smallest quantity giving a discernible erythema at 48 hr.

Challenge controls:

Control animals were topically applied with catechol but they were not previously injected with the inducer solution. They were employed at each dose level and almost never responded to the maximum test dose used.

Positive control substance(s):

not specified

Results and discussion

In vivo (non-LLNA)

Results

Results 1

Group:

positive control

Remarks on result:

no indication of skin sensitisation

Remarks:

Control animals were topically applied with catechol but they were not previously injected with the inducer solution. They were employed at each dose level and almost never responded to the maximum test dose used.

Results 2

Group:

negative control

Remarks on result:

other: no data

Results 3

Group:

test chemical

Remarks on result:

not measured/tested

Remarks:

The end point of this study is the smallest quantity giving a discernible erythema at 48 hr

Any other information on results incl. tables

Catechol never induced an observable sensitivity to less than 0.2 µmole with a geometric mean of 3.2 µmoles.

Applicant's summary and conclusion

Interpretation of results:

Category 1 (skin sensitising) based on GHS criteria

Conclusions:

Catechol induced delayed contact sensitivity in guinea pigs since majority of animals injected became sensitized. Catechol had low degree of sensitivity compared with other n-alkylcatechol.

Executive summary:

In a dermal sensitization study (Baer et al., 1967) with Catechol, 8 to 12 Hartley guinea pigs were tested using a modified method of Freund's complete adjuvant test.

Sensitisation was carried out by injection of an emulsion in complete Freund's adjuvant, at weekly intervals, successively into the nuchal area, the inguinal-axillary region and the foot pads.

Animals were given a skin test (topical application of catechol in acetone) 4 weeks after the last sensitising injection and then given two repetitive tests at 2-weeks intervals.

In this study, Catechol was used as inducer of sensitization and gave the appropriate response as “sensitizing”.

Catechol is considered as a skin sensitizer in this study.