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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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1996
Report date:
1996

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Version / remarks:
(1992)
GLP compliance:
yes
Type of study:
guinea pig maximisation test

Test material

Constituent 1
Chemical structure
Reference substance name:
-
EC Number:
425-240-7
EC Name:
-
Molecular formula:
C28H42O8Cl2Co2N12Zn4
IUPAC Name:
Zinc hexacyanocobaltate(III), tertiary butyl alcohol/polypropylene glycol complex

In vivo test system

Test animals

Species:
guinea pig
Strain:
Dunkin-Hartley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: D Hall Ltd., Burton on Trent, England.
- Age at study initiation: 5-7 weeks old
- Weight at study initiation: 380-452 g
- Housing: up to five animals were accommodated in suspended polypropylene cages with open tops and stainless steel mesh front panels; minimum internal dimensions 61 x 81 x 25 cm.
- Diet and water: ad libitum
- Acclimation period: at least 14 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 16-22 °C
- Humidity (%): not actively controlled, but expected to remain within the range 40-80%
- Air changes (per hr): at least 10
- Photoperiod (hrs dark / hrs light): 10/14

Study design: in vivo (non-LLNA)

Inductionopen allclose all
Route:
intradermal and epicutaneous
Vehicle:
other: Alembicol D
Concentration / amount:
for intradermal injection: 3.0% (m/v) in distilled water and/or adjuvant
for topical induction: 30% (m/m) in Alembicol D
for challenge: 30% and 15% (m/m) in Alembicol D
Challengeopen allclose all
Route:
epicutaneous, semiocclusive
Vehicle:
other: Alembicol D
Concentration / amount:
for intradermal injection: 3.0% (m/v) in distilled water and/or adjuvant
for topical induction: 30% (m/m) in Alembicol D
for challenge: 30% and 15% (m/m) in Alembicol D
No. of animals per dose:
10
Details on study design:
RANGE FINDING TESTS:
Intradermal injections incorporating a range of concentrations from 0.01% to 10% test substance in distilled water were made for range-finding. As a result 10 and 6 % (m/v) formulations were considered to be unsuitable for use in the main study due to difficulties during intradermal injections (preparations could not be administered to one animal). For topical inductions concentrations from 1% up to 30% in Alembicol D were used for range finding. The same concentration range was tested initially for topical application at challenge.

MAIN STUDY
A. INDUCTION EXPOSURE
Day 1 - Intradermal Induction: The dorsum of each test animal was clipped on the day before treatment commenced. On Day 1 single, straight rows of three intradermal injections (0.1 ml per site, anterior: FCA emulsion, middle: test substance 3% in distilled water, posterior: test substance 3% in FCA emulsion) were placed parallel to and on either side of the dorsal mid-line of each guinea pig.
Day 7 - Topical Induction: The previously (at least two hours before) shaved dorsal skin of each animal was subjected to application of a 25 x 45 mm patch of Whatman No 4 filter paper loaded with approx. 0.5 ml of the test substance 30% in Alembicol D or vehicle alone (control group). Occlusion of the treated skin was effected by successive layers of Blenderm, aluminium foil and Steroban. The patches and dressings remained in place for 48 hours.

B. CHALLENGE EXPOSURE
Day 22: The previously clipped and shaved (at least two hours before) right flanks were subjected to application of a 12 mm Finn chamber containing the formulation selected for challenge (30% or 15% (m/m) test substance in Alembicol D (left flanks were subjected to application of approx. 0.1 ml vehicle). The chambers were kept in place by successive layers of Blenderm and Steroban. The chambers and dressings were removed 24 hours after application and the treated areas of the skin were washed with arachis oil. Challenge sites were reshaved 21 hours after removal of the chambers. Dermal responses to challenge were assessed 24 and 48 hours after removal of the chambers.

OTHER: Test and control guinea pigs were observed daily for clinical signs of reaction to treatment. The guinea pigs were weighed on Day 1 and Day 25 following completion of the challenge phase.
Challenge controls:
For challenge control 5 animals (females) were treated epidermally with 30 or 15 % (m/m) test substance in Alembicol D under semiocclusive conditions for 24 hours.

Results and discussion

Positive control results:
Regular (six monthly) testing to moderately strong skin sensitiser 2-mercaptobenzothiazole.

In vivo (non-LLNA)

Resultsopen allclose all
Reading:
1st reading
Hours after challenge:
48
Group:
test chemical
Dose level:
30 %
No. with + reactions:
1
Total no. in group:
10
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 48.0. Group: test group. Dose level: 30 %. No with. + reactions: 1.0. Total no. in groups: 10.0.
Reading:
2nd reading
Hours after challenge:
72
Group:
test chemical
Dose level:
30 %
No. with + reactions:
1
Total no. in group:
10
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 72.0. Group: test group. Dose level: 30 %. No with. + reactions: 1.0. Total no. in groups: 10.0.
Reading:
1st reading
Hours after challenge:
48
Group:
test chemical
Dose level:
15 %
No. with + reactions:
2
Total no. in group:
10
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 48.0. Group: test group. Dose level: 15 %. No with. + reactions: 2.0. Total no. in groups: 10.0.
Reading:
2nd reading
Hours after challenge:
72
Group:
test chemical
Dose level:
15 %
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 72.0. Group: test group. Dose level: 15 %. No with. + reactions: 0.0. Total no. in groups: 10.0.
Reading:
1st reading
Hours after challenge:
48
Group:
negative control
Dose level:
30 %
No. with + reactions:
1
Total no. in group:
5
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 30 %. No with. + reactions: 1.0. Total no. in groups: 5.0.
Reading:
2nd reading
Hours after challenge:
72
Group:
negative control
Dose level:
30 %
No. with + reactions:
0
Total no. in group:
5
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 72.0. Group: negative control. Dose level: 30 %. No with. + reactions: 0.0. Total no. in groups: 5.0.
Reading:
1st reading
Hours after challenge:
48
Group:
negative control
Dose level:
15 %
No. with + reactions:
1
Total no. in group:
5
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 15 %. No with. + reactions: 1.0. Total no. in groups: 5.0.
Reading:
2nd reading
Hours after challenge:
72
Group:
negative control
Dose level:
15 %
No. with + reactions:
1
Total no. in group:
5
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 72.0. Group: negative control. Dose level: 15 %. No with. + reactions: 1.0. Total no. in groups: 5.0.

Any other information on results incl. tables

Maximum concentration not causing irritating effects in preliminary test: 30 %

Signs of irritation during induction:
Intradermal injection - no erythema at sites injected with test material in vehicle.

Topical application - slight erythema at treatment sites in test animals, none in controls.

Evidence of sensitisation of each challenge concentration: None

Other observations:
A similar level of mild irritation was apparent at sites challenged with Alembicol D only in both treated and control animals.

No clinical observations of ill health or toxicity were noted during the study.Body weight increases were recorded for all animals on Day 25 in comparison with Day 1.

 

Applicant's summary and conclusion

Executive summary:

A skin sensitisation test according to OECD TG 406 (GPMT) was conducted on 10 male or female guinea pigs receiving each three pairs of intradermal injections (anterior: FCA emulsion, middle: 3% test substance in distilled water, posterior: 3% test substance in FCA emulsion) and a topical application (30% test substance in Alembicol D) for induction. The challenge treatment was performed using either a 30 % or a 15% test substance formulation in Alembicol D. Dermal responses to challenge were assessed 48 and 72 hours after the beginning of the challenge treatment.

1/10 animals of the group receiving 30% test substance formulation for challenge and 2/10 animals of the group receiving 15% test substance formulation for challenge exhibited skin reactions. Each 1/5 animals of the control groups receiving 30% or 15% test substance formulation for challenge showed skin reactions. A similar level of mild irritation was also apparent at sites challenged with vehicle only in both treated and control animals. Thus, under the conditions of the test no skin sensitisation potential was detected.