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Toxicological information

Skin sensitisation

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Administrative data

Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Comparable to guideline study with acceptable restrictions: no data on clinical signs of local irritation or systemic toxicity, on body weights or on positive controls, sufficient documentation; study acceptable as key study
Cross-reference
Reason / purpose:
reference to other study

Data source

Reference
Reference Type:
publication
Title:
Assessment of the skin sentisation potential of topical medicaments using the local lymph node assay: an interlaboratory evaluation
Author:
Kimber I, Hilton J, Dearman RJ, Gerberick GF, Ryan CA, Basketter DA, Lea L, House RV, Ladics GS, Loveless SE, Hastings KL
Year:
1998
Bibliographic source:
J Toxicol Environ Health 53, 563 - 579

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
Deviations:
yes
Remarks:
(no data on clinical signs of local irritation or systemic toxicity, on body weights or on positive controls)
GLP compliance:
not specified
Type of study:
mouse local lymph node assay (LLNA)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): hydroquinone
- Analytical purity: > 99%
- Lot/batch No.: same batch used by all test laboratories

In vivo test system

Test animals

Species:
mouse
Strain:
CBA
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Harlan Seralab, Bicester, Oxfordshire, UK (Laboratories A and B), Harlan sprague-Dawley, Inc., Indianapolis, IN or Jackson Laboratories, Bar Harbour, ME, USA (Laboratories C, D and E)
- Age at study initiation: 6 - 12 w
- Weight at study initiation: no data
- Housing: no data
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: no data


ENVIRONMENTAL CONDITIONS: standard, no further details

Study design: in vivo (LLNA)

Vehicle:
acetone/olive oil (4:1 v/v)
Concentration:
0.10, 0.25, 0.50, 1.0, 2.5%
No. of animals per dose:
5
Details on study design:
RANGE FINDING TESTS: no data

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: standard LLNA protocol (Laboratories A and B), modified LLNA protocol 1 (Laboratories C and D), modified LLNA protocol 2 (Laboratories E)
- Criteria used to consider a positive response: Stimulation index of at least 3.0

TREATMENT PREPARATION AND ADMINISTRATION:
Standard LLNA protocol (pooled animal approach):
Application of 25 µL/d on the dorsum of both ears of the test substance solution or the vehicle alone on 3 consecutive days; i.v. application of [3H]-methylthymidine on day 6 followed by sacrifice 5 hrs later and excision of draining auricular lymph nodes, which were pooled for each experimental group; Incorporation of 3H-TdR measured in cell pellets by ß-scintillation counting

modified LLNA protocol 1 (individual animal approach):
comparable to standard protocol with the following exception: only lymph nodes of indivudual animals pooled

modified LLNA protocol 2 (individual animal approach):
comparable to modified LLNA protocol 1 with the following exception: use of [125I]iododeoxyuridine in place of 3H-TdR, incorporation of 125I-UdR measured by gamma-counter

Evaluations:
mean disintegration per minute (dpm) per node for each mouse or group;
stimulation index = increase in dpm of HQ-treated group relative to vehicle control group;
EC3-value: test concentration to elicit a stimulation index of SI = 3
Positive control substance(s):
not specified
Statistics:
Bartlett's test to examine the homogeneity of the within-chemical treatment variances; when analysis of variance revealed significant differences in parametric data, experiments were compared with vehicle controls using Dunnett's t-test, for nonparametric data use of Kruskal-Wallis test followed by Dunn's multiple comparison procedure, level of significance at P<= 0.05;
Test for dose-dependent effects by Jonckheere's test with level of significance at P<= 0.01
Comparison of stimulation indices for the 5 laboratories: analysis of covariance
Derivation of EC3-values: extrapolation from regression analyses

Results and discussion

In vivo (LLNA)

Resultsopen allclose all
Parameter:
SI
Remarks on result:
other: see Remark
Remarks:
Range at different test concentrations (result from 5 laboratories: 0.10%: 2.4 - 3.6; 0.25%: 4.8 - 14.9; 0.5%: 6.0 - 23.7; 1 %: 8.4 - 25.3; 2.5%: 12.2 - 33.4 Mean EC3 value calculated based on test results from 3 laboratories with values of 0.07%, 0.08% and 0.07%: mean 0.073% or 18 µg/cm2
Parameter:
other: disintegrations per minute (DPM)
Remarks on result:
other: see Table

Any other information on results incl. tables

Table: Test results in the interlaboratory evaluation of the LLNA

Test Laboratory

Para-meter

Vehicle control

Test concentration

EC3

in %

 EC3 in µg/cm2

0.10 %

0.25 %

0.50 %

1.00%

2.50%

A

dpm

342

973

1994

4685

5207

4489

0.07a

   17.5 

SI

-

2.8

5.8

13.7

15.2

13.1

B

dpm

347

936

2165

2259

3139

4555

0.03ad

    7.5

SI

-

2.5

5.8

6.0

8.4

12.2

C

dpm

781 ± 133

1858 ± 184 *

5484 ± 715 *

8668 ± 885 *

12412 ± 1203 *

11747 ± 1462 *

0.08a

    20.0

SI

-

2.4

7.0

11.1

15.9

15.0

D

dpm

257 ± 49

927 ± 215 *

1228 ± 385 *

3089 ± 753 *

3922 ± 546 *

5975 ± 631 *

0.07b

    17.5

SI

-

3.6

4.8

12.0

15.3

23.2

E

dpm

53 ± 19

167 ± 40 *

790 ± 204 *

1256 ± 219 *

1340 ± 108 *

1769 ± 163 *

c      

SI

-

3.2

14.9

23.7

25.3

33.4

SI = stimulation index

amathematically derived concentration required to induce a SI of 3

bderived by extrapolation

c Data set inappropriate for derivation of EC3 value by extrapolation. So these data were not considered for further evaluation

d As this EC3 value is distinctly different from the values of laboratories A, C and D, it was not considered for calculation of a mean EC3 value.

* statistically significantly different from control at P<0.05 (no statistical evaluation for Laboratories A and B)

Applicant's summary and conclusion

Interpretation of results:
sensitising
Remarks:
Migrated information
Conclusions:
A strong sensitising activity of hydroquinone was indicated in the mouse local lymph node assay in an interlaboratory evaluation with a mean EC3 value of 0.073% or 18 µg/cm2.
Executive summary:

The sensitising potential of hydroquinone was investigated in a mouse local lymph node assay comparable to standard conditions of the OECD Guideline 429 in an interlaboratory evaluation with participation of five test laboratories. Test concentrations were 0.10, 0.25, 0.50, 1.00, and 2.50% HQ in acetone/olive oil (4:1) as vehicle. A strong sensitising activity of hydroquinone was indicated by a mean EC3 value of 0.073% or 18 µg/cm2based on the most reliable test data.