Zinc Chelate Complex

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

read-across from similar mixture/product

Adequacy of study:

key study

Study period:

September - November 1995

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP-compliant guideline study

Cross-reference

Reason / purpose for cross-reference:

read-across: supporting information

Reference

Endpoint:

skin sensitisation, other

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Study period:

September - November 1995

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP-compliant guideline study

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

reference to other study

GLP compliance:

yes

Type of study:

guinea pig maximisation test

Species:

guinea pig

Key result

Remarks on result:

no indication of skin sensitisation

Remarks:

test item itself could not be tested as such, therefore, read.accross approach to decomposition product and analogeous substance

Interpretation of results:

not sensitising

Conclusions:

It is concluded that, under the conditions of the two in-vivo studies on the decomposition product and on the Zinc Chelate complex, repeated applications of the metal complex did not cause delayed contact hypersensitivity in the guinea-pig.

Executive summary:

The Zinc Chelate complex has been tested in-vivo in a Buehler test showing a non-sensitizing response. In addition the testing of the hydrolysis product LZ 399 in a maximization test was negative for dermal sensitization; zinc hydroxide and zinc sulfate did not produce a delayed contact sensitization response in the maximization tests and are not considered as a dermal sensitizers. The Buehler study was selected instead of the LLNA study design as the LLNA has shown to have false reading when used with metal compounds (as described in literature) and the Buehler is an acceptable substitute for the LLNA.

In-vivo studies carry more weight than in-vitro studies and are at the end of the key events sequence required to cause the presentation of allergic contact dermatitis according to the adverse outcome pathway (AOP) model. With the result of the in-vitro studies in conflict with the negative results for the in-vivo studies of the component and the degradation product, the weight of evidence leads to the conclusion that the Zinc Chelate Complex is not a dermal sensitizer, as the result of the component studies were all negative. 

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1996

Report date:

1996

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.6 (Skin Sensitisation)

Deviations:

no

GLP compliance:

yes

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

the maximization test was performed before the LLNA test methods was available

Test material

Test material information

Constituent 1

Test material form:

other: clear liquid

Details on test material:

- Name of test material (as cited in study report): P5117
- Physical state: clear, colourless liquid
- Purity test date: 25-Jul-1995
- Expiration date of the lot/batch: no data
- Stability under test conditions: stable
- Storage condition of test material: stored at ambient temperature

Specific details on test material used for the study:

- Storage conditions: Controlled room temperature (15-25°C, ≤70% relative humidity), protected from light and humidity (stored in a tightly closed container)

In vivo test system

Test animals

Species:

guinea pig

Strain:

Dunkin-Hartley

Sex:

male/female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: David Hall, Darley Oaks, Newchurch, Burton on Trent, Staffordshire, England
- Age at study initiation: 6-8 weeks
- Housing: gang housing; 5 animals of same sex per cage
- Diet (e.g. ad libitum): Guinea-pig F.D.1., from Special Diets Services Limited, Witham, Essex, England
- Water (e.g. ad libitum): Tap water
- Acclimation period: 6 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18°C
- Humidity (%): 55%
- Air changes (per hr): 10 air changes per hour
- Photoperiod (hrs dark / hrs light): 12 hours artificial light

Study design: in vivo (non-LLNA)

Induction

Induction 1

Route:

intradermal and epicutaneous

Vehicle:

water

Induction 2

Concentration / amount:

After consideration of the primary irritation screen results and the criteria for selection of treatment concentrations, the following regime was adopted:

First induction*:
- 50% v/v P5II7 in purified water
- 50% v/v P5II7 in FCA

Second induction*
- 10% v/v PSII7 in purified water

Challenge*
- 10% v/v P5II7 in purified water
- 3% v/v P5II7 in purified water

* Initially the first induction was undertaken employing 50% v/v formulations, however, due to ulceration of the administration sites the study was stopped. The study was restarted, with additional animals, using 5% v/v formulations

Challenge

Challenge 1

Route:

epicutaneous, occlusive

Vehicle:

water

Challenge 2

Concentration / amount:

After consideration of the primary irritation screen results and the criteria for selection of treatment concentrations, the following regime was adopted:

First induction*:
- 50% v/v P5II7 in purified water
- 50% v/v P5II7 in FCA

Second induction*
- 10% v/v PSII7 in purified water

Challenge*
- 10% v/v P5II7 in purified water
- 3% v/v P5II7 in purified water

* Initially the first induction was undertaken employing 50% v/v formulations, however, due to ulceration of the administration sites the study was stopped. The study was restarted, with additional animals, using 5% v/v formulations

No. of animals per dose:

- Control group: 5 animals per sex and group
- Test group: 10 animals per sex and group

Details on study design:

INDUCTION:
1. Primary induction
Three pairs of injections (0.1 m!) were made deep into the dermis, such that on either side of the dorsal median line there were three injection sites in a row parallel to the spinal column. AIl injection sites lay near the periphery of a dermal test site 2 cm wide x 4 cm long, overlying the scapulae. The anterior and middle sites were positioned close together and distant from the posterior sites.

Injection sites Test group treatment Control group treatment
Anterior sites (A) FCA FCA
Middle sites (B) Test material in vehicle Vehicle
Posterior sites (C) Test material in FCA Vehicle in FCA

2. Secondary induction
On Day 8, the dermal site overlying the scapulae were treated by topical application of 0.6 ml ofa test material formulation to test animals, while controls received 0.6 ml of the vehicle. Each dose was applied to a 4 x 2.5 cm absorbent patch (Whatman No. 3 filter paper) which was applied to the skin and covered by an occlusive dressing (Blenderm and Elastoplast) for 48 hours. The application site was wiped with a paper tissue moistened with the vehicle immediately after removal of the bandage.

CHALLENGE:
Both flanks of all animals were clipped on Day 21. On Day 22 these areas were wet shaven to reveal a 5 x 5 cm area on the left flank and a 10 x 5 cm area on the right flank. Approximately one hour later the left site was treated by topical application of 0.03 ml of the vehicle while the right side received 0.03 ml of the maximum non-irritant concentration (as determined by Phase 3 of the primary skin irritation screen) to one site and a dilution to a second site. The doses were applied to 1 cm diameter absorbent patches (AI-test) and cover ed by an occlusive dressing (Blenderm and Elastoplast) for 24 hours. The test site was wiped with a paper tissue moistened with vehicle immediately after removal of the bandage. Reactions to challenge were assessed approximately 24 and 48 hours after removal of the occlusive dressings. The observations were made without knowledge of the number or group identity of the animal under examination.

Positive control substance(s):

not specified

Results and discussion

In vivo (non-LLNA)

Results

Results 1

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

3% test item in purified water

No. with + reactions:

0

Total no. in group:

20

Clinical observations:

none

Remarks on result:

no indication of skin sensitisation

Results 2

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

10% test item in purified water

No. with + reactions:

8

Total no. in group:

20

Clinical observations:

these responses reflected primary irritation rather than dermal sensitization.

Remarks on result:

no indication of skin sensitisation

Results 3

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

3% test item in purified water

No. with + reactions:

0

Total no. in group:

20

Clinical observations:

none

Remarks on result:

no indication of skin sensitisation

Results 4

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

10% test item in purified water

No. with + reactions:

8

Total no. in group:

20

Clinical observations:

these responses reflected primary irritation rather than dermal sensitization.none

Remarks on result:

no indication of skin sensitisation

Results 5

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

purified water

No. with + reactions:

4

Total no. in group:

10

Clinical observations:

these responses reflected primary irritation rather than dermal sensitization.

Remarks on result:

no indication of skin sensitisation

Results 6

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

purified water

No. with + reactions:

4

Total no. in group:

10

Clinical observations:

these responses reflected primary irritation rather than dermal sensitization.

Remarks on result:

no indication of skin sensitisation

Results 7

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

positive control

Remarks on result:

not measured/tested

Results 8

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

positive control

Remarks on result:

not measured/tested

Any other information on results incl. tables

Slight erythema or a more marked reaction were observed in eight of twenty test and four often control animals following challenge with 10% P5117 in purified water and in no animal following challenge application of 3% P5117 in purified water (the maximum non-irritant concentration). No animal showed a reaction to challenge application of purified water alone.

Since the incidence and severity of responses to challenge with the 10% formulation was the same in the test and control animals and none of the responders showed a reaction after challenging with 3% P5117, it is considered that they reflected primary irritation rather than dermal sensitization. No positive responses to challenge with 3% P5117 were found.

Applicant's summary and conclusion

Interpretation of results:

not sensitising

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

It is concluded that, under the conditions of this study, repeated applications of LZ399 did not cause delayed contact hypersensitivity in the guinea-pig.

Executive summary:

The skin sensitisation potential of LZ399 was assessed in maximization test (Magnusson & Kligman) according to methds OECD no. 406 and EU B.6 on guinea pigs. 20 animals were used in the test group and 10 animals in the control group. Concentrations of 3% and 10% test item in purified water were tested. Challenge application of 10% test item in purified water gave rise to slight erythema or a more marked reaction in eight of twenty test and four of ten control animals. It is considered that these responses reflected primary irritation rather than dermal sensitization. Challenge application of 3% test item caused no positive response in test or control animals. Challenge application of purified water alone caused no significant response. It was concluded that, under the conditions of this study and the criteria of the EC, repeated administration of LZ399 did not cause delayed contact hypersensitivity in guinea-pigs.