Trichloroacetic acid

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Test method was equivalent to OECD guideline 406. No data on GLP.

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

2002

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Deviations:

no

GLP compliance:

not specified

Type of study:

guinea pig maximisation test

Test material

Test material information

Constituent 1

Reference substance name:

Trichloroacetic acid

EC Number:

200-927-2

EC Name:

Trichloroacetic acid

Cas Number:

76-03-9

Molecular formula:

C2HCl3O2

IUPAC Name:

trichloroacetic acid

Details on test material:

- Name of test material (as cited in study report): Trichloroacetic acid

In vivo test system

Test animals

Species:

guinea pig

Strain:

other: FMMU strain (Albino)

Sex:

not specified

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Medical Laboratory Animal Center of the First Military Medical University, China.
- Weight at study initiation: 300-350 g
- Diet and water (e.g. ad libitum): The animals were fed with a standard guinea pig diet, fresh vegetable and tap water.
- Acclimation period: 1 week

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 23 ± 1.5 ºC
- Humidity (%): 55 ± 10%
- Photoperiod (hrs dark / hrs light): 12 h day/night cycle

Study design: in vivo (non-LLNA)

Induction

Induction 1

Route:

intradermal and epicutaneous

Vehicle:

other: olive oil or distilled water, and FCA (Freund’s Complete Adjuvant)

Induction 2

Concentration / amount:

For induction:
- Intradermal concentration: 0.5 %
- Topical concentration: 5.0 %
For challenge:
- Topical concentration: 2.0 %

Challenge

Challenge 1

Route:

epicutaneous, occlusive

Vehicle:

other: olive oil or distilled water, and FCA (Freund’s Complete Adjuvant)

Challenge 2

Concentration / amount:

For induction:
- Intradermal concentration: 0.5 %
- Topical concentration: 5.0 %
For challenge:
- Topical concentration: 2.0 %

No. of animals per dose:

The number of guinea pigs for each group was 10-14.

Details on study design:

- Control group: Freund’s Complete Adjuvant (FCA) and olive oil were used as control agents.

Before the starting of challenge phases, primary irritant studies had been performed by 3-4 fresh animals. An area of 4cm x 6 cm on the back of animals were clipped free of hair. 24 h later, the intact animals were selected in the test.

Filter paper impregnated with the test material and mounted on Leucoflex (Beiersdorff AG) was used for the topical induction patch test.

The Guniea Pig Maximixation Test (GPMT) was performed as described by Magnusson & Kligman (1969) with some modifications. For induction, dorsal skin in the scapular region was shaved. 24 h later, 3 pairs of 0.1 mL intradermal injections were performed: (i) an emulsified mixture of FCA; (ii) a suspension of test agent in olive oil or in distilled water; (iii) a suspension of test agent in FCA. 7 days after injection, the interscapular region was again shaved, and treated with w (SLS)=10 % in the groups into which olive oil and FCA (non-irritant) were injected. 8 days later, 0.2 mL of test agent preparation was occlusively patched on the same region for 48 h. Control animals were supplied with vehicles only.
21 days after the initial intradermal injection, all animals were challenged by topical application of test agent. 0.1 mL test agent in vehicles was applied to the shaved areas of the guinea pigs by closed patch test method, and left for 24 h. Patch test responses were read 24 h and 48 h after removing the patches. Allergenic reactions observed in animal groups were graded as follows: 0, no reaction; 1, scattered mild redness; 2, moderate and diffuse
redness; 3, intensive erythema and swelling.
The important statistics in these tests, however, was not the intensity but the frequency of sensitization. Based upon the percentage of animals sensitized, the grading of allergenicity was calculated. The allergenic potency of the tested agents was classified according to Magnusson and Kligman.
Skin of the test site and the controls was taken by punch biopsies, then fixed in 10% neutral phosphate-buffered formalin solution w (HCHO)=10 %, embedded in glycol methacrylate and polyethlene glycol, cut into 3 m sections and stained with May-Grunwald-Giemsa. Light microscopic assessment was performed with a 1000 x oil immersion lens.

Positive control substance(s):

yes

Remarks:

(1,2- dinitrochlorobenzene)

Results and discussion

Positive control results:

Sensitization rate: 100.0%
In the positive group (2,4-dinitrochlorobenzene), the challenge affected skin showed inflammatory cell infiltration in the cornification, corium and granular cell layers. Granular cells were slightly swollen. No abnormality was found in basal cells. The capillary vessle expanding and edema with the mononuclear infiltration were found in corium.

In vivo (non-LLNA)

Results

Results 1

Hours after challenge:

24

Group:

test chemical

No. with + reactions:

7

Total no. in group:

12

Clinical observations:

(Sensitization rate: 58.3 %; Score of redness: 13; Score of Swelling: 0; Mean score: 1.1)

Remarks on result:

other: . Hours after challenge: 24.0. Group: test group. No with. + reactions: 7.0. Total no. in groups: 12.0. Clinical observations: (Sensitization rate: 58.3 %; Score of redness: 13; Score of Swelling: 0; Mean score: 1.1).

Results 2

Hours after challenge:

48

Group:

test chemical

No. with + reactions:

7

Total no. in group:

12

Clinical observations:

(Sensitization rate: 58.3 %; Score of redness: 13; Score of Swelling: 0; Mean score: 1.1)

Remarks on result:

other: . Hours after challenge: 48.0. Group: test group. No with. + reactions: 7.0. Total no. in groups: 12.0. Clinical observations: (Sensitization rate: 58.3 %; Score of redness: 13; Score of Swelling: 0; Mean score: 1.1).

Any other information on results incl. tables

The histopathological analysis also showed an induction of allergenic transfomation in guinea pig skin by trichloroacetic acid.

Applicant's summary and conclusion

Interpretation of results:

sensitising

Remarks:

Migrated information (in this study the substances classified as strong sensitisers produced redness and swelling. However, in the case of the substance trichloroacetic acid, only a weak score of redness was observed).

Conclusions:

Trichloroacetic acid appears to be a moderate allergen.

Executive summary:

To study the contact allergenic activity of trichloroacetic acid a modified guinea pig maximization test (GPMT) was adopted.

The skin sensitization (edema and erythema) was observed in trichloroacetic acid. The allergenic rate of trichloroacetic acid was 58.3%. The mean response score of trichloroacetic acid was 1.1. The histopathological analysis also showed an induction of allergenic transfomation in guinea pig skin by trichloroacetic acid. Trichloroacetic acid appears to be a moderate allergen.