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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:
7 November 1995 to 30 September 1997
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
The restrictions were deviations from the guideline: temperature and humidity were sometimes slightly higher than recommended; sodium lauryl sulphate was not applied to the skin prior to induction 2.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1997
Report date:
1997

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Deviations:
yes
Remarks:
(relative humidity range was 52 to 75% (not recommended to exceed 70%), temperature range of 21 to 25 °C (19 to 23 °C recommended), sodium lauryl sulphate not applied to skin prior to induction 2 (recommended for non-irritants))
GLP compliance:
yes
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
An LLNA study was not performed because there is an existing reliable study for skin sensitisation using the Guinea Pig Maximisation test method. Furthermore, the LLNA test method is not considered to be suitable for substances that contain silicon. Please refer to the attached document for further details.

Test material

Constituent 1

In vivo test system

Test animals

Species:
guinea pig
Strain:
Hartley
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Sasco, Inc., Madison, WI
- Age at study initiation: ~6 weeks
- Weight at study initiation: 321 to 485 g
- Housing: individually in stainless steel wire cages
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: ~3 weeks

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21 to 25
- Humidity (%): 52 to 75
- Air changes (per hr): no data
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: 21 November 1995 To: 18 December 1995

Study design: in vivo (non-LLNA)

Induction
Route:
intradermal and epicutaneous
Vehicle:
other: Dow Corning(R) 360 Medical Fluid
Concentration / amount:
5% (first induction and challenge), 100% (second induction)
Challenge
No.:
#1
Route:
intradermal and epicutaneous
Vehicle:
other: Dow Corning(R) 360 Medical Fluid
Concentration / amount:
5% (first induction and challenge), 100% (second induction)
No. of animals per dose:
20 (and 10 positive and 10 vehicle control animals)
Details on study design:
RANGE FINDING TESTS: 0.1 ml intradermal injections of 2.5 and 5% test material with Freund's complete adjuvant and 0.9% saline were tolerated locally and systemically by two guinea pigs. 0.3 ml of various concentrations of test material applied under Hill Top Chambers to shaved skin for 48 hours produced different levels of erythema among four guinea pigs (see Table 1 in "Any other information on results incl. tables").

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 2
- Exposure period: n/a (first induction, intradermal injection), ~48 hours (second induction, topical application)
- Test groups:
- Induction #1: six intradermal injections of 0.1 ml (2 x test material, 2 x saline/Freund's complete adjuvant, 2 x test material/saline/Freund's complete adjuvant).
- Induction #2: 1.5 ml topical test material, wrapped in elastic adhesive bandage for approximately 48 hours.
- Control group: as above, but vehicle and positive control groups administered undiluted Dow Corning(R) 360 Medical Fluid and 0.1% 1-chloro-2,4-dinitrobenzene (in propylene glycol) respectively instead of test material
- Site: skin over the scapula (shaved)
- Frequency of applications: weekly (day 1 and day 8)
- Concentrations: 5% (first induction - intradermal), 100% (second induction - topical)

B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day(s) of challenge: day 22
- Exposure period: 24 hours
- Test groups: 0.3 ml test material on left flank, 0.3 ml vehicle on the right
- Vehicle control group: 0.3 ml test material on right flank, 0.3 ml vehicle on the left
- Positive control group: 0.3 ml 1-chloro-2,4-dinitrobenzene (DNCB) in propylene glycol (PG) on left flank, 0.3 ml PG on the right flank
- Site: upper flank (shaved)
- Concentrations: 5% test substance, 0.1% DNCB, vehicles (including PG) undiluted
- Evaluation (hr after challenge): 24 and 48 hours after patch removal (48 and 72 hours after application) (See "Any other information on materials and methods incl. tables" for information on scoring of skin effects)

OTHER
- Guinea pigs were observed daily for mortality and morbidity during treatment
- Animals were weighed weekly (i.e. prior to dosing on dosing days)
Challenge controls:
Vehicle control animals treated with test material and vehicle, positive control animals treated with DNCB in propylene glycol, and propylene glycol.
Positive control substance(s):
yes
Remarks:
1-chloro-2,4-dinitrobenzene (in propylene glycol)

Results and discussion

Positive control results:
All animals treated with the positive control substance exhibited reactions indicative of sensitisation (i.e. erythema scores of at least 1) on the first (24-hour) and second (48-hour) readings after challenge patch removal.

In vivo (non-LLNA)

Resultsopen allclose all
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
5% test material
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
none of the test animals exhibited a positive response at any time during the study
Remarks on result:
no indication of skin sensitisation
Reading:
2nd reading
Hours after challenge:
48
Group:
test chemical
Dose level:
5% test material
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
none of the test animals exhibited a positive response at any time during the study
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
0.3 ml vehicle
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
none of the vehicle control animals exhibited a positive response at any time during the study
Remarks on result:
no indication of skin sensitisation
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
0.3 ml vehicle
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
none of the vehicle control animals exhibited a positive response at any time during the study
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
1-chloro-2,4-dinitrobenzene (in propylene glycol)
No. with + reactions:
10
Total no. in group:
10
Clinical observations:
All animals treated with the positive control substance exhibited a positive response at the first and second reading, with severity indices of 3.30 and 3.20 respectively
Remarks on result:
positive indication of skin sensitisation
Reading:
2nd reading
Hours after challenge:
48
Group:
positive control
Dose level:
1-chloro-2,4-dinitrobenzene (in propylene glycol)
No. with + reactions:
10
Total no. in group:
10
Clinical observations:
All animals treated with the positive control substance exhibited a positive response at the first and second reading, with severity indices of 3.30 and 3.20 respectively
Remarks on result:
positive indication of skin sensitisation

Any other information on results incl. tables

Table 1: Irritant/corrosive response data for each animal at each observation time in the preliminary test

Test substance concentration (topically applied)

Erythema (24-hour)

Erythema (48-hour)

Max. score: 4

Max. score: 4

100%

2/2/2/1

1/1/1/1 

75%

2/2/1/0

1/1/0/0

50%

2/1/0/0

1/0/0/0

25%

2/1/0/0

0/0/0/0

 

All animals gained weight over the course of the study.

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
In a GLP-compliant guinea pig maximisation test, performed in accordance with OECD Test Guideline 406, twenty male guinea pigs exhibited no reactions indicative of skin sensitisation when treated with the test material.
Executive summary:

A guinea pig maximisation test was carried out according to OECD Test Guideline 406 and in compliance with GLP to assess the skin sensitising potential of the test material.

 

In the induction phase of the study, on day one, the shaved fur over the scapulae of twenty male guinea pigs were given two lots of 0.1 ml intradermal injections of the test material (at 5% in Dow Corning® 360 Medical Fluid), the 5% test material with saline and Freund’s complete adjuvant, and saline and Freund’s complete adjuvant. One week later (day eight), the same region was shaved again and saturated with 1.5 ml of neat test material, applied topically, and wrapped with an elastic adhesive bandage for 48 hours. Groups of 10 control animals were treated similarly with the vehicle (Dow Corning® 360 Medical Fluid) or the positive control substance (1-chloro-2,4-dinitrobenzene in propylene glycol).

 

On day 22 a challenge application of 0.3 ml 5% test material and 0.3 ml of the undiluted vehicle were each applied to one shaved flank of both the test and vehicle control animals. Positive control animals instead received 0.1% DNCB and undiluted propylene glycol. The application sites were covered with an adhesive bandage for 24 hours, with reactions read 48 and 72 hours after application (24 and 48 hours after bandage removal).

 

All positive control animals exhibited reactions indicative of sensitisation at both the 24- and 48-hour readings. There were no skin reactions seen at either time point for any of the test or vehicle control animals.

 

Under the conditions of this study, the test material was not sensitising to the skin of male guinea pigs.