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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
Study period:
23 July 1997 - 22 August 1997
Reliability:
1 (reliable without restriction)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1998
Report Date:
1998

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
EPA OTS 798.4100 (Skin Sensitisation)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method B.6 (Skin Sensitisation)
Deviations:
no
Qualifier:
according to
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Deviations:
no
Qualifier:
according to
Guideline:
other: Notification Yakushin 1 No. 24 11 September 1989, Pharmaceutical Affairs Bureau, MOHW "Skin Sensitization Tests".
Deviations:
no
GLP compliance:
yes
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
study was conducted prior to the date that revised guidance was issued

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Benzoflex 9-88 (Dipropylene glycol dibenzoate; DPGDB)
- Physical state: Clear colourless liquid
- Analytical purity: Dipropylene glycol dibenzoate - 89.4% (w/w)
- Impurities (identity and concentrations):
Dipropylene glycol monobenzoate - 4.98% (w/w)
Propylene glycol dibenzoate - 2.29% (w/w)
Propylene glycol monobenzoate - 0.28% (w/w)
Propenyloxy propyl benzoate - 2.35% (w/w)
- Lot/batch No.: 56635211
- Expiration date of the lot/batch : September 1998
- Storage condition of test material: Room temperature

In vivo test system

Test animals

Species:
guinea pig
Strain:
Dunkin-Hartley
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: D Hall, Newchurch, Staffordshire, England
- Age at study initiation: Approximately 4 to 7 weeks
- Weight at study initiation: 325 to 438 g
- Housing: Housed in groups of five in suspended metal cages with wire mesh floors.
- Diet: Vitamin C enriched guinea pig diet FD2 was provided ad libitum. Hay was given weekly.
- Water: drinking water providede ad libitum
- Acclimation period: 5 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19 to 28.5°C
- Humidity (%): 44 to 66%
- Air changes (per hr): 15
- Photoperiod: 12 hours light per 24 hour period


IN-LIFE DATES: From: 23 July 1997 To: 22 August 1997

Study design: in vivo (non-LLNA)

Inductionopen allclose all
Route:
intradermal and epicutaneous
Vehicle:
other: None for induction injection and application; Alembicol D for the challenge application.
Concentration / amount:
Used as supplied for topical and intradermal injection induction exposures; Used as supplied and as 50% (v/v) in Alembicol D for the topical challenge exposure.
Challengeopen allclose all
Route:
epicutaneous, semiocclusive
Vehicle:
other: None for induction injection and application; Alembicol D for the challenge application.
Concentration / amount:
Used as supplied for topical and intradermal injection induction exposures; Used as supplied and as 50% (v/v) in Alembicol D for the topical challenge exposure.
No. of animals per dose:
20 for test substance group and test substance vehicle control group; 10 for positive control group and vehicle control group to positive control group.
Details on study design:
RANGE FINDING TESTS:
The intradermal and topical irritancy of a range of dilutions of the test substance was investigated to identify where possible (a) concentrations of the test substance that would produce irritation suitable for the induction phase of the main study and (b) a maximum non-irritant concentration by the
topical route of administration for the challenge phase. Animals for these investigations were pre treated with an intradermal injection of Freund's
complete adjuvant (FCA) 50:50 with water for irrigation (Ph Eur) at least one week prior to the start of the preliminary investigations.

The procedure employed for these investigations was as follows:
Intradermal injections - Intradermal injections (0.1 mL/site) were made into the clipped flank of a total of four guinea pigs, using a range of
concentrations of the test material in a suitable vehicle. As no adverse reactions were observed for the first two guinea pigs receiving concentrations 0.1 - 10% v/v, further concentrations (20-100% v/v) were investigated. The resulting dermal responses were assessed approximately 24 and 72
hours later.

Topical application - Approximately 0.5 mL of each of a range of concentrations of the test substance in a suitable vehicle was applied to patches of
surgical gauze (20 x 20mm). These were placed on the clipped and shaved flanks of each of four guinea pigs. The patches were covered by a strip of "Blenderm" and firmly secured by "Elastoplast" wound round the trunk and covered with "Sleek impervious" plastic adhesive tape. After an exposure
period of approximately 6 hours, the dressings were removed and the reaction sites were assessed for erythema and oedema on a numerical basis
according to the system given. Further examination ofthe sites was carried out approximately 24 and 48 hours after removal of the dressings.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 2 (One by intradermal injections, one by topical application)
- Exposure period: 8 days (6 days following injections plus two days following dermal application).
- Test groups: 1) FCA in water (50/50 v/v); 2) Test substance as supplied; 3) Test substance in FCA (50/50 v/v).
- Control group: Vehicle control for test substance, Positive control (hexyl cinnamic aldehyde (HCA)), Vehicle control for positive control.
- Site: Scapular region
- Frequency of applications: As noted above.

B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day(s) of challenge: One day, two weeks after topical induction.
- Exposure period: 24 hours
- Test groups: Test group and vehicle control group were exposed to 0.2 mL test substance and 0.2 mL test substance in Alembicol D (50% v/v).
- Control group: Positive control groups were exposed to HCA and HCA 50% in Alembicol D
- Site: Test substance or HCA as supplied was applied to an anterior site; test substance or HCA in Alembicol D was applied to the posterior site.
- Evaluation (hr after challenge): 24 and 48

Challenge controls:
The control and test animals were challenged topically two weeks after the topical induction application using Benzoflex 9- 88 as supplied and 50% v/v in Alembicol D.
Positive control substance(s):
yes
Remarks:
Hexyl cinnamic aldehyde

Results and discussion

Positive control results:
Evidence of skin sensitization was produced by hexyl cinnamic aldehyde (HCA) in all ten test animals thus confirming sensitivity of this test method.

In vivo (non-LLNA)

Resultsopen allclose all
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
0.2 mL, material as supplied or 50% in Alembicol
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
No signs of ill health or toxicity were recorded.
Remarks on result:
other: see Remark
Remarks:
Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 0.2 mL, material as supplied or 50% in Alembicol. No with. + reactions: 0.0. Total no. in groups: 20.0. Clinical observations: No signs of ill health or toxicity were recorded..
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
0.2 mL, material as supplied or 50% in Alembicol
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
No signs of ill health or toxicity were recorded.
Remarks on result:
other: see Remark
Remarks:
Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 0.2 mL, material as supplied or 50% in Alembicol. No with. + reactions: 0.0. Total no. in groups: 20.0. Clinical observations: No signs of ill health or toxicity were recorded..
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
10% v/v
No. with + reactions:
10
Total no. in group:
10
Clinical observations:
evidence of skin sensitization
Remarks on result:
positive indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
positive control
Dose level:
10% v/v
No. with + reactions:
10
Total no. in group:
10
Clinical observations:
evidence of skin sensitization
Remarks on result:
positive indication of skin sensitisation
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
0
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
no evidence of skin sensitization
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
0
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
no evidence of skin sensitization
Remarks on result:
no indication of skin sensitisation

Applicant's summary and conclusion

Interpretation of results:
not sensitising
Remarks:
Migrated information
Conclusions:
In this study DPGDB did not produce evidence of skin sensitization (delayed contact hypersensitivity) in any of the twenty test animals.
Evidence of skin sensitization was produced by hexyl cinnamic aldehyde (HCA) in all of the ten positive control test animals thus confirming the sensitivity of the method.
Executive summary:

A study was performed to assess the skin sensitization potential of the test substance DPGDB to guinea pigs. The study was conducted in accordance with OECD, EC and US EPA test guidelines, and in compliance with GLP.

The test substance was used as supplied for topical and intradermal injection induction exposures and as supplied and as a 50% (v/v) solution in Alembicol D for topical challenge exposure.

Hexyl cinnamic aldehyde was used as positive control. Evidence of skin sensitization was seen in all animals treated with this substance, but no reactions were observed in the control group, confirming the sensitivity of the method. 

No evidence of toxicity or ill health were recorded for any animal exposed to the test substance. There were no dermal reactions seen in any of the test animals, therefore all these animals gave negative responses.

DPGDB did not produce evidence of skin sensitization (delayed contact hypersensitivity) in any of the animals tested.