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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:
From 10 May 1994 to 17 June 1994
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1994
Report date:
1994

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method B.6 (Skin Sensitisation)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
Data from a reliable in vivo test conducted before the enforcement of Commission Regulation (EU) 640/2012 of 06 July 2012 amending, for the purpose of its adaptation to technical progress, Regulation (EC) No. 440/2008 laying down test methods pursuant to Regulation (EC) No 1907/2006 of the European Parliament and of the Council on the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) are available.

Test material

Constituent 1
Chemical structure
Reference substance name:
Reaction mass of Cobaltate(1-), bis[6-(amino-κN)-5-[2-[2-(hydroxy-κO)-4-nitrophenyl]diazenyl-κN1]-N-methyl-2-naphthalenesulfonamidato(2-)]-, sodium (1:1) and disodium [6-amino-5-[(2-hydroxy-4-nitrophenyl)azo]-N-methylnaphthalene-2-sulphonamidato(2-)][6-amino-5-[(2-hydroxy-4-nitrophenyl)azo]naphthalene-2-sulphonato(3-)]cobaltate(2-)
EC Number:
943-062-2
Molecular formula:
not available
IUPAC Name:
Reaction mass of Cobaltate(1-), bis[6-(amino-κN)-5-[2-[2-(hydroxy-κO)-4-nitrophenyl]diazenyl-κN1]-N-methyl-2-naphthalenesulfonamidato(2-)]-, sodium (1:1) and disodium [6-amino-5-[(2-hydroxy-4-nitrophenyl)azo]-N-methylnaphthalene-2-sulphonamidato(2-)][6-amino-5-[(2-hydroxy-4-nitrophenyl)azo]naphthalene-2-sulphonato(3-)]cobaltate(2-)
Test material form:
not specified
Specific details on test material used for the study:
Identification: IRGALAN BLAU 3GL ROH FEUCHT (FAT 20'036/F)

Description: Black solid

Batch Number: 1

Purity / Formulation: approx. 97.7%

Stability of Test Article: Stable in storage condition;

Expiration date: 07/99

Stability of Test Article in Vehicle: unknown in water and in vaselinum album and in a (1:1 v/v) mixture of FCA/physiological saline, excluded from the Statement of Compliance.

Storage Conditions: at room temperature (approx. 20 °C) away from direct sunlight

Safety precautions: Gloves, goggles and face mask were obligatory to ensure personnel health and safety.

In vivo test system

Test animals

Species:
guinea pig
Strain:
other: Ibm:GOHI; SPF quality guinea pigs.Himalayan spotted.
Sex:
female
Details on test animals and environmental conditions:
-Test system: Ibm: GOHI; SPF quality (synonym: Himalayan spotted) guinea pigs.
- Rationale: Recognized by the international guidelines as the recommended test system (e.g. OECD, EEC).
- Source: BRL, Biological Research Laboratories Ltd. Wölferstrasse 4, 4414 Füllinsdorf/Switzerland
- Number of animals for main study / pretest: 30 females/6 females
- Age at beginning of Acclimatization period: approx. 5-7 weeks
- Body Weight at beginning of Acclimatization period: Control and Test Group: 342 - 411 g and Pretest: 348 - 397 g
- Identification: By unique cage number and corresponding ear tags.
- Randomization: Randomly selected at time of delivery.
- Acclimatization: One week for the control and test group under test conditions after health examination. No acclimatization for the animals of the pretest. Only animals without any visual signs of illness were used for the study.

Conditions:
Standard Laboratory Conditions:
Air-conditioned with 10-15 air changes per hour and continuously monitored environment with a temperature between 21 - 23.5 degrees Celsius, a relative humidity between 56 - 74 %, 12 hours artificial fluorescent light (approx. 100 Lux) /12 hours dark, music during the light period. The duration of the cleaning process was approximately 30 minutes.

Accommodation:
Individually in Makrolon type-3 cages (size: 22x37x15 cm) with standard softwood bedding ("Lignocel", Schill AG, CH-4132 Muttenz).

Diet:
Pelleted standard Kliba 342, Batch nos. 61/94 (at delivery of the animals to 07-APR-1994) and 62/94 (from 08-APR-1994 to termination of test) guinea pig breeding/ maintenance diet ("Kliba", Klingentalmühle AG, CH-4303 Kaiseraugst), ad libitum.

Water:
Community tap water from Füllinsdorf, ad libitum. Once weekly additional supply of ascorbic acid (1 g/l) via the drinking water.

Study design: in vivo (non-LLNA)

Inductionopen allclose all
Route:
intradermal
Vehicle:
physiological saline
Concentration / amount:
1 %
Day(s)/duration:
Day 1
Adequacy of induction:
highest concentration used causing mild-to-moderate skin irritation and well-tolerated systemically
Route:
epicutaneous, occlusive
Vehicle:
other: Vaselinum album
Concentration / amount:
25 %
Day(s)/duration:
Day 8
Adequacy of induction:
highest technically applicable concentration used
Challengeopen allclose all
No.:
#1
Route:
epicutaneous, occlusive
Vehicle:
other: vaseline album
Concentration / amount:
25 %
Day(s)/duration:
Day 22
Adequacy of challenge:
highest non-irritant concentration
No.:
#2
Route:
epicutaneous, occlusive
Vehicle:
other: Vaselinum album
Concentration / amount:
25 %
Day(s)/duration:
Day 29
Adequacy of challenge:
highest non-irritant concentration
No. of animals per dose:
- 30 females were used in the main study :(10 females were used as control group and 20 females were used as test group).
- 6 females were used in the pretest.
Details on study design:
PRETEST / performed during the acclimatization period.
INTRADERMAL INJECTIONS:
Intradermal injections (0.1 ml/site) were made into the clipped flank of two guinea-pigs at concentration of 5, 3 and 1% of the test article in bi-distilled water. The resulting dermal reactions were assessed 24 hours later. For intradermal induction application a 1% test article dilution was selected.

EPIDERMAL APPLICATIONS:
Both flanks of each of 4 guinea pigs were clipped and shaved just prior to the application. Thereafter 4 patches* of filter papers (2 x 2 cm) were saturated with the test article, at A = 25% (this concentration used was found to be the most qualified to assure an optimum technical application procedure), B = 15%, C = 10% and D = 5% of the test article in vaselinum album and applied to the clipped and shaved flanks. The patches were covered by a strip of aluminum foil and firmly secured by elastic plaster wrapped around the trunk and covered with impervious adhesive tape. This procedure ensured the intensive contact of the test article. The dressings were removed after an exposure period of 24 hours.

21 hours after removing of the dressing the application site was depilated with an approved depilatory cream (VEET Cream, Reckitt & Colman AG, CH-4123 Allschwil) to clean the application site from staining produced by the test article, so that possible erythema reactions were clearly visible at that time. The depilatory was placed on the patch sites and surrounding areas and left on for 3-5 minutes. It was then thoroughly washed off with a stream of warm, running water. The animals were then dried with a disposable towel and returned to their cages.
The reaction sites were assessed 24 and 48 hours after removal of the bandage for erythema and edema on a numerical basis according to Draize.

For the epidermal induction and challenge procedure the test article at 25% was selected.


MAIN STUDY

INDUCTION
Intradermal injections / performed on test day 1:
An area of dorsal skin from the scapular region (approximately 6 x 8 cm) was clipped free of hair. Three pairs of intradermal injections (0.1 ml/site) were made at the border of a 4 x 6 cm area in the clipped region as follows:

Test group:
1) 1:1 (v/v) mixture of Freund's Complete Adjuvant and physiological saline.
2) The test article, diluted to 1% with bi-distilled water.
3)* The test article diluted to 1% by emulsion in a 1:1 (v/v) mixture of Freund's Complete Adjuvant and physiological saline.

Control Group:
1) 1:1 (v/v) mixture of Freund's Complete Adjuvant and physiological saline.
2) Bi-distilled water
3)* 1:1 (w/w) mixture of bi-distilled in a 1:1 (v/v) mixture of Freund's Complete Adjuvant and physiological saline.


Epidermal applications / performed on test day 8:
On test day 7 and approximately 21 hours prior to the epidermal application the scapular area (approximately 6 x 8 cm) was clipped, shaved free of hair and the test area was pretreated with 10 % Sodium-Lauryl-Sulfate (SLS) in paraffinum perliquidum as no primary irritation had been observed in the pretest. The SLS was massaged into the skin with a glass rod without bandaging. This 10% concentration of SLS enhances sensitization by provoking a mild inflammatory reaction.

On test day 8 a 2 x 4 cm patch of filter paper was saturated with the test article (25% in vaselinum album) and placed over the injection sites of the test animals. The patch was covered with aluminum foil and firmly secured by an elastic plaster wrapped around the trunk of the animal and secured with impervious adhesive tape. The dressings were left in place for 48 hours. The epidermal application procedure described ensured intensive contact of the test article.

The guinea-pigs of the control group were treated as described above with vaselinum album only.
Reaction sites were assessed for erythema and edema 24 and 48 hours after removal of the dressing, using the numerical grading system according to Draize.


FIRST CHALLENGE / performed on test day 22
The test and control guinea-pigs were challenged two weeks after the epidermal induction application. The test and control guinea-pigs were treated in the same way.

Hair was clipped and shaved from a 5 x 5 cm area on the left and right flank of each guinea-pig just prior to the application. Two patches ( 2 x 2 cm) of filter paper were saturated with the non-irritating concentration of 25% (left flank) and the vehicle only (vaselinum album, applied to the right flank) using the same method as for the epidermal application. The dressing was left in place for 24 hours.

21 hours after removing of the dressing the test sites were depilated with an approved depilatory cream (VEET Cream, Reckitt & Colman AG, CH-4123 Allschwil). The cream was placed on the patch sites for 3-5 minutes and then washed off with a stream of warm running water. When the application sites were clean and any stains from the test article removed the animals were dried with a disposable paper towel and returned to their cages.

24 and 48 hours after the removal of the dressing the application sites were assessed for erythema and oedema using the numerical scoring system according to Draize.

SECOND CHALLENGE / performed on test day 29
A second challenge was performed one week after the first challenge. The treatment procedure used for the animals in the control and test group was the same as that described for the first challenge except the applications were made to the opposite flanks of the guinea pigs.
Challenge controls:
None
Positive control substance(s):
yes
Remarks:
4-Aminobenzoic acid ethyl ester

Results and discussion

Positive control results:
For validation of the sensitivity of test method and test system used, a known (4-AMIN0BENZ0IC ACID ETHYL ESTER) was selected as a positive control. This was performed in accordance with the recommendation of the OECD for testing of chemicals number 406 "Skin Sensitization Test", adopted by the council on July
17, 1992 (reported Paris, April 29, 1993).
According to the procedures used in this experiment (run from 15-NOV to 28-DEC- 1993) positive results were observed in the treated animals after the epidermal challenge application.

The intradermal induction was performed with a dilution at 1% in mineral oil. For the induction period and challenge procedure a 25% dilution of 4-AMINOBE ZOIC ACID ETHYL ESTER in mineral oil was used. This concentration was found in a pretest to be the highest primary not-irritant concentration. The test article at 10% and 5% in mineral oil was additionally applied in the second challenge to compare with the literature.
From the results described above moderate allergenic potency (grade 3) of the test article 4-AMINOBENZOIC ACID ETHYL ESTER was concluded. The results were interpreted according to the rating of Magnusson and Kligman (1969).
The response of at least 30% positive animals is considered positive "R43" following the "Commission Directive 93/21/EEC, April 27, 1993 adapting to
technical progress for the 18th time Council Directive 67/548/EEC on the approximation of the laws, regulations and administrative provisions relating to the classification, packaging and labelling of dangerous substances.
In this study 30-50% of the animals were positive after treatment with a nonirritant test substance concentration of 25% and with concentrations of 10% and
5% in mineral oil. Therefore according to EEC (European Economic Community) classification criteria described in guidelines 93/21/EEC (EEC Official Journal Nr. L 110A, May 04, 1993), this test article is considered to be a sensitizer ("R43").

In vivo (non-LLNA)

Resultsopen allclose all
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
test item 25%
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
No, erythema reaction after the first and the second challenge procedure.
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
test item 25%
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
No, erythema reaction after the first and the second challenge procedure.
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
Inductions: Intradermal 1%, epidermal 25%, Challenge 1 & 2: 25 %
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
No, erythema reaction after the first and the second challenge procedure.
Reading:
2nd reading
Hours after challenge:
48
Group:
test chemical
Dose level:
Inductions: Intradermal 1%, epidermal 25%, Challenge 1 & 2: 25 %
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
No, erythema reaction after the first and the second challenge procedure.
Reading:
rechallenge
Hours after challenge:
24
Group:
test chemical
Dose level:
Inductions: Intradermal 1%, epidermal 25%, Challenge 1 & 2: 25 %
No. with + reactions:
0
Total no. in group:
20
Reading:
rechallenge
Hours after challenge:
48
Group:
test chemical
Dose level:
Inductions: Intradermal 1%, epidermal 25%, Challenge 1 & 2: 25 %
No. with + reactions:
0
Total no. in group:
20
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
25%
No. with + reactions:
10
Total no. in group:
20
Remarks on result:
other: positive control: 4-AMIN0BENZ0IC ACID ETHYL ESTER
Reading:
2nd reading
Hours after challenge:
48
Group:
positive control
Dose level:
25 %
No. with + reactions:
9
Total no. in group:
20
Remarks on result:
other: positive control: 4-AMIN0BENZ0IC ACID ETHYL ESTER
Reading:
rechallenge
Hours after challenge:
24
Group:
positive control
Dose level:
10%
No. with + reactions:
8
Total no. in group:
20
Remarks on result:
other: positive control: 4-AMIN0BENZ0IC ACID ETHYL ESTER
Reading:
rechallenge
Hours after challenge:
48
Group:
positive control
Dose level:
10 %
No. with + reactions:
7
Total no. in group:
20
Remarks on result:
other: positive control: 4-AMIN0BENZ0IC ACID ETHYL ESTER
Reading:
rechallenge
Hours after challenge:
24
Group:
positive control
Dose level:
5 %
No. with + reactions:
6
Total no. in group:
20
Remarks on result:
other: positive control: 4-AMIN0BENZ0IC ACID ETHYL ESTER
Reading:
rechallenge
Hours after challenge:
48
Group:
positive control
Dose level:
5 %
No. with + reactions:
6
Total no. in group:
20
Remarks on result:
other: positive control: 4-AMIN0BENZ0IC ACID ETHYL ESTER

Any other information on results incl. tables

RESULTS

Main Study

SKIN EFFECTS AFTER INTRADERMAL INDUCTION PERFORMED ON TEST DAY 1

CONTROL GROUP

- Injection site 1 : (1:1 (v/v) mixture of Freund's Complete Adjuvant [FCA] and physiological saline)

The area around the injection site was oedematous and erythematous from test day 2 to 4 and 2 to 5 respectively and then became necrotic from test day 6 to 10 followed by encrustation and exfoliation of encrustation up to test day 32 (termination of test).

- Injection site 2 (bi-distilled water)

The area around the injection site was oedematous and erythematous from test day 2 to 4.

- Injection site 3 (1:1 (w/w) mixture of bi-distilled water in a 1:1 (v/v) mixture of FCA and physiological saline)

The reactions observed were identical to those obtained at injection site 1 with the mixture of FCA and physiological saline. As the animals were bandaged with the semi-occlusive dressing no observations of the skin were possible on test day 9.

TEST GROUP

- Injection site 1 (1:1 (v/v) mixture of Freund's Complete Adjuvant [FCA] and physiological saline)

The reactions observed were identical to those obtained in the control group with the mixture of FCA and physiological saline, at injection site 1.

- Injection site 2 (1% solution of test article in bi-distilled water)

The area around the injection site was oedematous and dark blue discolored from test day 2 to 4 and 2 to 16 respectively, necrotic from test day 6 to 10. Encrustation was observed from test day 11 to 16 followed by exfoliation of encrustation up to the termination of test.

- Injection site 3 (1% solution of test article in a 1:1 (v/v) mixture of FCA and physiological saline)

The reactions observed were identical to those obtained at injection site 2 in the test group. As the animals were bandaged with the semi-occlusive dressing no observations of the skin were possible on test day 9.

SKIN EFFECTS AFTER EPIDERMAL INDUCTION PERFORMED ON TEST DAY 8

CONTROL GROUP:

No erythematous or oedematous reaction was observed in the animals treated with vaselinum album only.

TEST GROUP:

As the test article stained the skin dark blue, it was not possible to determine whether erythema was present. However, no oedema was observed.

Dark bluediscolouration was noted from test day 10 to 23. All the animals were pretreated with a 10% SLS in paraffinum perliquidum

SKIN EFFECTS AFTER THE FIRST AND SECOND CHALLENGE PERFORMED ON TEST DAY 22 AND 29 RESPECTIVELY

CONTROL (FIRST AND SECOND CHALLENGE):

No positive reactions were observed in the animals either when treated with vaselinum album alone or when treated with the test article at 25% in vaselinum album.

Dark blue discolouration was noted from test day 23 (after removal of the dressing to 24 (prior to the depilation) in the first challenge and from test day 30 (after removal of the dressing) to 31 (prior to the depilation).

TEST GROUP (FIRST AND SECOND CHALLENGE)

No positive reactions were observed in the animals either when treated with vaselinum album alone or when treated with the test article at 25% in vaselinum album.

Dark blue discolouration was noted from test day 23 (after removal of the dressing to 24 (prior to the depilation) in the first challenge and from test day 30 (after removal of the dressing) to 31 (prior to the depilation)

VIABILITY / MORTALITY / MACROSCOPIC FINDINGS

As there were no deaths during the course of the treatment period no necropsies were performed.

CLINICAL SIGNS, SYSTEMIC

No symptoms of systemic toxicity were observed in the animals.

BODY WEIGHTS

Two animals of the epidermal pretest lost weight during the acclimatization period. The loss of weight should be considered to be of incidental nature.

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
No animals of the test group showed positive allergic response after treatment with a non-irritant test substance concentration of 25 % in vaselinum album. No positive reactions were observed in the control group. The test article should be considered to be a non-sensitizer.
Executive summary:

To assess the allergenic potential of the test item in albino guinea pigs, a test was performed according to the OECD Guidelines for Testing of Chemicals, Section 4, number 406, "Skin Sensitization", adopted July 17, 1992 (reported Paris 29 April 1993).

Ten males were used as control group and 20 males were used as test group. The highest non-irritating test article concentration used for challenge application was 25% in vaselinum album.

POSITIVE ERYTHEMA REACTIONS AFTER THE FIRST CHALLENGE PROCEDURE

   After 24 hours After 48 hours 
   Positive / total  Positive / total
   % positive of total  % positive of total
 Control group 
 (FAT 20036/F), 25% (left flank)  0/10 ----0  0/10 ----0
 Vaseline album only (right flank)  0/10 ---- 0  0/10 -----0
 Test group
  (FAT 20036/F), 25% (left flank)  0/20 ----0 0.20 ----0
  Vaseline album only (right flank)  0/20 ----0  0/20 ----0

POSITIVE ERYTHEMA REACTIONS AFTER THE SECOND CHALLENGE PROCEDURE

   After 24 hours After 48 hours 
   Positive / total  Positive / total
   % positive of total  % positive of total
 Control group 
   
 Vaseline album only (left flank)  0/10 ---- 0  0/10 -----0
 Test group
  (FAT 20036/F), 25% (right flank)  0/20 ----0 0.20 ----0
  Vaseline album only (left flank)  0/20 ----0  0/20 ----0

No toxic symptoms were evident in the guinea pigs of the control or test group. No deaths occurred.

CONCLUSION

No animals of the test group showed positive allergic response after treatment with a non-irritant test substance concentration of 25% in vaselinum album. No positive reactions were observed in the control group. The test article should be considered to be a non-sensitizer.