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Skin sensitisation

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Administrative data

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
other: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
From December 20, 1988 to January 27, 1989
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail
Remarks:
Source study has reliability 2. Details on the read across are attached in section 13.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1989

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Version / remarks:
adopted on May 12, 1981
Qualifier:
according to guideline
Guideline:
EU Method B.6 (Skin Sensitisation)
GLP compliance:
yes
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
GPMT was already available.

Test material

Constituent 1
Reference substance name:
Similar Substance 02
IUPAC Name:
Similar Substance 02
Test material form:
solid

In vivo test system

Test animals

Species:
guinea pig
Strain:
Dunkin-Hartley
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Wiga, Sulzfeld / West Germany.
- Age at study initiation: approximately 11 weeks.
- Weight: 318 - 455 gram, at acclimatisation.
- Housing: group housing of 2 animals per half of metal cages with wire-mesh floors.
- Diet: free access to standard guinea pig diet, including ascorbic acid (1600 mg/kg); LC 23-B, pellet diameter 4mm. In addition, once a week hay was provided.
- Water: free access to tap-water, diluted with decalcified water.
- Acclimation period: at least five days under test conditions after physical examination.

ENVIRONMENTAL CONDITIONS
- Temperature: 21 ± 3 °C
- Humidity: 30 - 70 %
- Air changes: air-conditioned with 7.5-15 air changes per hour.
- Photoperiod: 12 hours artificial fluorescent light/12 hours dark.

Study design: in vivo (non-LLNA)

Inductionopen allclose all
Route:
intradermal
Vehicle:
water
Remarks:
aqua dest
Concentration / amount:
5 %
Route:
epicutaneous, occlusive
Vehicle:
water
Remarks:
milli-RO water
Concentration / amount:
25 %
Day(s)/duration:
48 hours
Challenge
Route:
epicutaneous, occlusive
Vehicle:
water
Remarks:
milli-RO water
Concentration / amount:
2, 5, 10 %
Day(s)/duration:
24 hours
No. of animals per dose:
10 females for the control group and 20 females for the experimental group
5 animals were used for the primary irritation test, one week before the main study.
Details on study design:
RANGE FINDING TESTS
Objective of this investigation was to identify irritant test article concentrations suitable for the induction phase of the main study. In addition, a suitable non-irritant concentration of test article, by topical route of administration, was identified for the challenge application.
Any systemic toxic effects may also be detected in primary irritation experiments.

Intradermal injections
Four intradermal injections (0.1 ml/site) were made into the clipped shoulder region of one guinea pig at a concentration of 5 % (w/w) of test article in milli-RO water. The resulting dermal reactions were assessed 24 hours later.

Epidermal applications
The intracutaneously injected animal was also treated epicutaneously at the shaved left fiank with 0.5 ml of a 50 % concentration of the test article in milli-RO water using a Metalline patch mounted on Micropore and held in place with Coban for 24 hours. The treated skin was assessed for erythema 24 and 48 hours after removal of dressings on a numerical basis.
Four animals were shaved on the left fiank and exposed for 24 hours to 50 %, 25 %, 10 % and 5 % (w/w) test article concentrations in milli-RO water (0.05 ml/concentration), occlusively administered by means of Square chambers mounted on Micropore. The bandage was fixed in place by means of Cuban. Reaction sites were assessed for erythema on a numerical basis, 24 and 48 hours after removal of the dressings.

MAIN STUDY
A. INDUCTION EXPOSURE
Intradermal application
On day 1 an area of the dorsal skin from the scapular region (approximately 6 × 8 cm) was clipped free of hair. Three pairs of intradermal injections (0.1 ml/site) were made at the border of a 4 × 6 cm area in the clipped region as follows:
A) test article dissolved to 5 % (wlw) with aqua dest (pyrogene free)
B) Freunds’ Complete Adjuvant, 50:50 with distilled water for injection
C) test article, at twice the concentration used in (A), emulsified in a 50:50 mixture of Freunds’ Complete Adjuvant.

Epidermal applications
Seven days after the intradermal injections, the scapular area (approximately 6 × 8 cm) was again clipped and shaved free of hair. A 2 × 4 cm patch of Metalline mounted on Micropore was treated with 0.5 ml of the test article (25 % (wlw) in milli-RO water) and placed over the injection sites of test animals. The Micropore tape was firmly secured, wrapped around the trunk of the animal and secured with Cuban. The dressings were left in place for approximately 48 hours.
The epidermal application procedure described ensured intensive contact of the test article even if it is insoluble in the vehicle used.
The guinea pigs of the control group were treated as described above by the intradermal and epidermal inductions with the omission of test article.
Reaction sites were assessed for erythema immediately after removal of the dressings, using the numerical grading system.

B. CHALLENGE EXPOSURE
Test and control guinea pigs were challenged two weeks after the epidermal induction application.
Hair was clipped and shaved from a 5 × 5 cm area on the left flank of each guinea-pig. The following series of 3 test article concentrations and the vehicle were applied using Square chambers, attached to Micropore tape:
a = 10 % in milli-RO water
b = 5 % in milli-RO water
c = 2 % in milli-RO water
d = milli-RO water
Of each concentration and vehicle, 0.05 ml was brought on the Square chamber. The patch was placed on shaved area, Micropore firmly secured, wound around the trunk of the animals and held in place by Coban.
Dressings and residual test article were removed after approximately 24 hours.
Sites were assessed for redness and swelling 24 and 48 hours after removal of the dressings, using the numerical grading system (modified from Kligman A.M., J. Invest. Dermatol. 47, 1966).
Test sites were shaved with an electric razor after the first reading.
Positive control substance(s):
yes
Remarks:
a positive control experiment is carried out once a year as a sensitivity check of test system. The last before experiment was carried out in December 1988

Results and discussion

In vivo (non-LLNA)

Resultsopen allclose all
Reading:
2nd reading
Hours after challenge:
48
Group:
test chemical
Dose level:
0, 2, 5, 10 %
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
no symptoms of systemic toxicity were observed.
Remarks on result:
no indication of skin sensitisation
Reading:
other: challenge
Hours after challenge:
48
Group:
negative control
Dose level:
0 % milli-RO water
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
no symptoms of systemic toxicity were observed.
Remarks on result:
no indication of skin sensitisation
Reading:
other: challenge
Group:
positive control
Dose level:
0.5 %
No. with + reactions:
18
Total no. in group:
20
Clinical observations:
-
Remarks on result:
positive indication of skin sensitisation

Any other information on results incl. tables

RANGE FINDING TESTS

No signs of systemic toxicity were observed during the primary irritation experiments.

INDUCTION

All experimental animals showed skin irritation after the 48 hours occluded epicutaneous induction exposure.

CHALLENGE

Control group: no positive skin reactions were evident after the challenge exposure.

Experimental group: none of the animals showed a positive reaction in response to any of the challenge concentrations.

TOXICITY SYMPTOMS / MORTALITY

No symptoms of systemic toxicity were observed in the animals during the study. No mortality occurred during the study.

BODY WEIGHTS

The average body weight gain of experimental and control animals was similar.

Applicant's summary and conclusion

Interpretation of results:
other: not classified, according to the CLP Regulation (EC 1272/2008)
Conclusions:
Non-sensitising
Executive summary:

Skin sensitisation potential of test substance was assayed according to OECD guideline 406. 35 female guinea pig were used: 10 females for control group and 20 females for test group; the remaining 5 animals were used for the primary irritation test, one week before the main study.

In accordance with Magnusson and Kilgman (1969) and based on the findings in the primary irritation experiments, the following concentrations were selected for induction and challenge phase: intracutaneous induction at 5 % (w/w) in aqua dest and epicutaneous induction at 25 % (w/w) in milli-RO water; challenge at 0, 2, 5, and 10 % (w/w) in milli-RO water.

Under test conditions, test item sensitisation rate was of 0 per cent, after intracutaneous and epicutaneous application to the guinea pig. No symptoms of systemic toxicity were seen; no mortality occurred; average body weight gain of test and control animals was similar.

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