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Diss Factsheets

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:
no data
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Remarks:
Modified Magnusson and Kligman procedure. The HQ experiment included only 4 animals per group. Challenge applications were open.

Data source

Reference
Reference Type:
publication
Title:
Experimental study on cross-reactivity of α-arbutin toward p-phenylenediamine and hydroquinone in guinea pigs
Author:
To-o K., Nomura K., Sugimoto K., Bishimura T., Kuriki T., Itoh M.
Year:
2010
Bibliographic source:
J. Dermatol. 37: 455-462

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
In principle the methodology was similar to OECD Guideline 406 (Skin Sensitisation) except the HQ sensitisation assay included a smaller number of animals (4 animals/group) and open application was used at challenge.
GLP compliance:
not specified
Remarks:
publication, University laboratories
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
Data from a research organization; not originally produced for regulatory purposes.

Test material

Constituent 1
Chemical structure
Reference substance name:
Hydroquinone
EC Number:
204-617-8
EC Name:
Hydroquinone
Cas Number:
123-31-9
Molecular formula:
C6H6O2
IUPAC Name:
hydroquinone
Test material form:
not specified
Details on test material:
- Name of test material : Hydroquinone
- Physical state: no data
- source: Wako Pure Chemicals Industries, Osaka, Japan

In vivo test system

Test animals

Species:
guinea pig
Strain:
Dunkin-Hartley
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: no data
- Age at study initiation: no data
- Weight at study initiation: 400g
- Housing: individual cages
- Diet (e.g. ad libitum): standard solid diet ad libitum (RC-4 oriental Yeast, Osaka, Japan)
- Water (e.g. ad libitum): tap water, ad libitum
- Acclimation period: no data

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 23 +/- 2°C
- Humidity (%): 55 +/- 10°C
- Air changes (per hr): no data
- Photoperiod (hrs dark / hrs light): 12/12 h light/dark cycle

IN-LIFE DATES: no data

Study design: in vivo (non-LLNA)

Inductionopen allclose all
Route:
intradermal and epicutaneous
Vehicle:
other: acetone 80%
Concentration / amount:
On day 0, intradermal injections at 3 different spots:
1) 0.05 ml emulsified mixture of FCA and saline
2) 0.05 ml of 2% hydroquinone in saline
3) 0.05 ml of 2% hydroquinone in emulsified mixture of FCA and saline (1:1)

Challengeopen allclose all
Route:
epicutaneous, open
Vehicle:
other: acetone 80%
Concentration / amount:
On day 0, intradermal injections at 3 different spots:
1) 0.05 ml emulsified mixture of FCA and saline
2) 0.05 ml of 2% hydroquinone in saline
3) 0.05 ml of 2% hydroquinone in emulsified mixture of FCA and saline (1:1)

No. of animals per dose:
4 females/dose
Details on study design:
MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 1 intradermal injection on day 0 and one topical application on day 7
- Site: shaved flanks
- Frequency of applications: single application
- Concentrations:
On day 0, intradermal injections at 3 different spots:
1) 0.05 ml emulsified mixture of FCA and saline
2) 0.05 ml of 2% hydroquinone in saline
3) 0.05 ml of 2% hydroquinone in emulsified mixture of FCA and saline (1:1)
On day 7, topical induction with 0.5 g of 1% hydroquinone in petrolatum applied under an occlusive patch for 48 hrs.

B. CHALLENGE EXPOSURE
- No. of exposures: one application
- Day(s) of challenge: day 21
- Exposure period: 24 hrs, open application
- Test groups: hydroquinone in 80% acetone
- Control group: vehicle (acetone at 80% in water)
- Site: flank regions that had been shaved 24h before challenge
- Concentrations: 0.2%, 2% or 20% hydroquinone (0.05 ml containing 0.1, 1, or 10 mg HQ)
- Evaluation (hr after challenge): 24h, 48h, 72 h

Challenge controls:
none
Positive control substance(s):
no
Remarks:
Hydroquinone was the positive control in the study investigating cross-reactivity

Results and discussion

In vivo (non-LLNA)

Resultsopen allclose all
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
0.2%
No. with + reactions:
3
Total no. in group:
4
Remarks on result:
other: Hydroquinone was the positive control, see details under test chemical
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
vehicle
No. with + reactions:
0
Total no. in group:
4
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: vehicle. No with. + reactions: 0.0. Total no. in groups: 4.0.
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
0.2%
No. with + reactions:
3
Total no. in group:
4
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 0.2%. No with. + reactions: 3.0. Total no. in groups: 4.0.
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
2%
No. with + reactions:
4
Total no. in group:
4
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 2%. No with. + reactions: 4.0. Total no. in groups: 4.0.
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
2%
No. with + reactions:
4
Total no. in group:
4
Remarks on result:
other: Hydroquinone was the positive control, see details under test chemical
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
20%
No. with + reactions:
4
Total no. in group:
4
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 20%. No with. + reactions: 4.0. Total no. in groups: 4.0.
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
20%
No. with + reactions:
4
Total no. in group:
4
Remarks on result:
other: Hydroquinone was the positive control, see details under test chemical
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
vehicle
No. with + reactions:
0
Total no. in group:
4
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: vehicle. No with. + reactions: 0.0. Total no. in groups: 4.0.
Reading:
2nd reading
Hours after challenge:
48
Group:
test chemical
Dose level:
0.2%
No. with + reactions:
3
Total no. in group:
4
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 0.2%. No with. + reactions: 3.0. Total no. in groups: 4.0.
Reading:
2nd reading
Hours after challenge:
48
Group:
positive control
Dose level:
0.2%
No. with + reactions:
3
Total no. in group:
4
Remarks on result:
other: Hydroquinone was the positive control, see details under test chemical
Reading:
2nd reading
Hours after challenge:
48
Group:
test chemical
Dose level:
2%
No. with + reactions:
3
Total no. in group:
4
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 2%. No with. + reactions: 3.0. Total no. in groups: 4.0.
Reading:
2nd reading
Hours after challenge:
48
Group:
positive control
Dose level:
2%
No. with + reactions:
3
Total no. in group:
4
Remarks on result:
other: Hydroquinone was the positive control, see details under test chemical
Reading:
2nd reading
Hours after challenge:
48
Group:
test chemical
Dose level:
20%
No. with + reactions:
4
Total no. in group:
4
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 20%. No with. + reactions: 4.0. Total no. in groups: 4.0.
Reading:
2nd reading
Hours after challenge:
48
Group:
positive control
Dose level:
20%
No. with + reactions:
4
Total no. in group:
4
Remarks on result:
other: Hydroquinone was the positive control, see details under test chemical
Reading:
other: 3rd reading
Hours after challenge:
72
Group:
negative control
Dose level:
vehicle
No. with + reactions:
0
Total no. in group:
4
Remarks on result:
other: Reading: other: 3rd reading. . Hours after challenge: 72.0. Group: negative control. Dose level: vehicle. No with. + reactions: 0.0. Total no. in groups: 4.0.
Reading:
other: 3rd reading
Hours after challenge:
72
Group:
test chemical
Dose level:
0.2%
No. with + reactions:
2
Total no. in group:
4
Remarks on result:
other: Reading: other: 3rd reading. . Hours after challenge: 72.0. Group: test group. Dose level: 0.2%. No with. + reactions: 2.0. Total no. in groups: 4.0.
Reading:
other: 3rd reading
Hours after challenge:
72
Group:
positive control
Dose level:
0.2%
No. with + reactions:
2
Total no. in group:
4
Remarks on result:
other: Hydroquinone was the positive control, see details under test chemical
Reading:
other: 3rd reading
Hours after challenge:
72
Group:
test chemical
Dose level:
2%
No. with + reactions:
2
Total no. in group:
4
Remarks on result:
other: Reading: other: 3rd reading. . Hours after challenge: 72.0. Group: test group. Dose level: 2%. No with. + reactions: 2.0. Total no. in groups: 4.0.
Reading:
other: 3rd reading
Hours after challenge:
72
Group:
positive control
Dose level:
2%
No. with + reactions:
2
Total no. in group:
4
Remarks on result:
other: Hydroquinone was the positive control, see details under test chemical
Reading:
other: 3rd reading
Hours after challenge:
72
Group:
test chemical
Dose level:
20%
No. with + reactions:
4
Total no. in group:
4
Remarks on result:
other: Reading: other: 3rd reading. . Hours after challenge: 72.0. Group: test group. Dose level: 20%. No with. + reactions: 4.0. Total no. in groups: 4.0.
Reading:
other: 3rd reading
Hours after challenge:
72
Group:
positive control
Dose level:
20%
No. with + reactions:
4
Total no. in group:
4
Remarks on result:
other: Hydroquinone was the positive control, see details under test chemical

Applicant's summary and conclusion

Interpretation of results:
Category 1B (indication of skin sensitising potential) based on GHS criteria
Conclusions:
The results showed the sensitising potential of Hydroquinone following intradermal induction at 2%, followed by an occlusive topical induction at 0.2, 2 or 20% in 80% acetone, and challenge with open applications at the same dose levels. Based on criteria described in CLP Regulation (EC) 1272/2008, the substance meets the criteria of sensitiser sub-category 1B (≥ 30 % responding at > 1 % intradermal induction dose).