A mixture of: O,O-di(1-methylethyl)trithio-bis-thioformate; O,O-di(1-methylethyl)tetrathio-bis-thioformate; O,O-di(1-methylethyl)pentathio-bis-thioformate

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Study was undertaken between 27 October and 21 November 1987.

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study conducted in accordance with generally accepted scientific principles, possibly with incomplete or methodological deficiencies, which do not affect the quality of relevant results.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1988

Report date:

1988

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:

not specified

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

The reason why a non-LLNA test was conducted is that this test pre-dates the requirements for an LLNA-type test and is in accordance with the testing requirements of that time.

Test material

Test material information

Constituent 1

Reference substance name:

Di-isopropyl xanthogen polysulphide

IUPAC Name:

Di-isopropyl xanthogen polysulphide

Details on test material:

- Name of test material (as cited in study report): D.I.X.T
- Physical state: Clear yellow, oily liquid
- Storage condition of test material: ambient temperature in the dark

In vivo test system

Test animals

Species:

guinea pig

Strain:

Dunkin-Hartley

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Obtained from D. Hall, Newchurch, Staffordshire, England.
- Weight at study initiation: Test animals: 318-372 g (mean: 353 g). Control animals: 310-360 g (mean: 337 g)
- Housing: The guinea-pigs were housed in suspended cages with wire mesh floors.
- Diet (e.g. ad libitum): Free access to a Vitamin C-enriched Guinea-Pig Diet F.D.l (Special Diets Services Limited). Hay was given once weekly.
- Water (e.g. ad libitum): Free access to tap water.
- Acclimation period: The guinea-pigs selected for the study were all acclimated to the laboratory environment.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): Room temperature was approximately 21°C
- Humidity (%): Relative humidity 30-70%
- Air changes (per hr): Air exchange was maintained at approximately 15 air changes per hour.
- Photoperiod (hrs dark / hrs light): lighting was controlled by means of a time switch to give 12 hours of artificial light in each 24 hour period.

Study design: in vivo (non-LLNA)

Induction

Induction 1

Route:

intradermal and epicutaneous

Vehicle:

unchanged (no vehicle)

Induction 2

Concentration / amount:

Induction:
Intradermal injection: 1% v/v in iquid paraffin
Topical application: Neat (as supplied)

Challenge:
Neat (as supplied) and as 50% v/v in liquid parafinn.

Challenge

Challenge 1

Route:

epicutaneous, occlusive

Vehicle:

unchanged (no vehicle)

Challenge 2

Concentration / amount:

Induction:
Intradermal injection: 1% v/v in iquid paraffin
Topical application: Neat (as supplied)

Challenge:
Neat (as supplied) and as 50% v/v in liquid parafinn.

No. of animals per dose:

Test animals: 20
Control animals: 10

Details on study design:

RANGE FINDING TESTS:
The intradermal and topical irritancy of a range of dilutions of D. I . X. T. was investigated to identify (a ) irritant test substance concentrations suitable for the induction phase of the main study and (b) non-irritant concentrations by the topical route of administration for the challenge phase.

The following concentrations of D.I.X.T. were selected:
Induction:-
Intradermal injection: 1% v/v in liquid paraffin.
Topical application: As supplied.
Challenge:-
As supplied and 50% v/v in liquid paraffin.


MAIN STUDY
A. INDUCTION EXPOSURE

Intrademal injections:
A 4 x 6 cm area of dorsal skin on the scapular region of the guinea-pig was clipped free of hair with electric clippers. Three pairs of intradermal injections were made simultaneously into this area.
Injectab1es were prepared as follows:
1. Freund's complete adjuvant was diluted with an equal volume of water for irrigation.
2. D.I.X.T., 1% v/v in liquid paraffin.
3. D.I.X.T., 1% v/v in a 50 : 50 mixture of Freund's complete adjuvant and liquid paraffin.

Topical application:
One week after the injections, the same 4 x 6 cm interscapular area was clipped and shaved free of hair.
A 2 x 4 cm patch of Whatman No. 3 paper was saturated with D.l.X.T., as supplied. The patch was placed on the skin and covered by a length of impermeable plastic adhesive tape (5 cm width "Blenderm"). This in turn was firmly secured by elastic adhesive bandage ("Elastoplast" 5 cm width) wound round the torso of the animal and fixed with "Sleek" impervious plastic adhesive tape. The dressing was left in place for 48 hours.


B. CHALLENGE EXPOSURE
The test and control animals were challenged topically two weeks after the induction period using D.l.X.T., as supplied and 50% v/v in liquid paraffin.

Hair was removed by clipping and then shaving from an area on the left flank of each guinea-pig. A 2 x 2 cm patch of Whatman No. 3 paper was saturated with approximately 0.2 ml of D.l.X.T., as supplied and applied to an anterior site on the flank. D.l.X.T. 50% v/v in liquid paraffin was applied in a similar manner to a posterior site. The patches were sealed to the flank for 24 hours under strips of "Blenderm" covered by "Elastoplast" wound round the trunk and secured with "Sleek".

READING CHALLENGE REACTIONS:
The challenge sites were evaluated 24, 48 and 72 hours after removal of the patches. The numerical scores awarded to dermal reactions resulting from the challenge application are shown in Table 1 (see attached background material).
Reactions were scored according to the following arbitrary scale:

Erythema and eschar formation:
No erythema: 0
Very slight erythema (barely perceptible): 1
Well-defined erythema: 2
Moderate to severe erythema: 3
Severe erythema (beet redness) to slight eschar formation (injuries in depth): 4

Oedema formation:
No oedema: 0
Very slight oedema (barely perceptible): 1
Slight oedema (edges of area well-defined by definite raising): 2
Moderate oedema (raised approximately 1 millimetre): 3
Severe oedema (raised more than 1 millimetre and extending beyond the area of exposure): 4

Challenge controls:

Control animals:
During the induction period the control animals were treated similarly to the test animals with the exception that the test compound was omitted from the intradermal injections and topical application.

Positive control substance(s):

no

Results and discussion

In vivo (non-LLNA)

Results

Results 1

Key result

Reading:

other: 3rd reading

Hours after challenge:

72

Group:

test chemical

Dose level:

neat and 50% v/v in liquid parafinn

No. with + reactions:

20

Total no. in group:

20

Clinical observations:

Dryness and sloughing of the epidermis, thickening, dryness and sloughing of the epidermis partially obscuring erythema, necrotic edge, necrotic patch, necrosis (see Table 1)

Remarks on result:

other: see Remark

Remarks:

Reading: other: 3rd reading. . Hours after challenge: 72.0. Group: test group. Dose level: neat and 50% v/v in liquid parafinn. No with. + reactions: 20.0. Total no. in groups: 20.0. Clinical observations: Dryness and sloughing of the epidermis, thickening, dryness and sloughing of the epidermis partially obscuring erythema, necrotic edge, necrotic patch, necrosis (see Table 1).

Results 2

Key result

Reading:

1st reading

Hours after challenge:

72

Group:

negative control

No. with + reactions:

0

Total no. in group:

9

Clinical observations:

Localised dermal reaction

Remarks on result:

no indication of skin sensitisation

Any other information on results incl. tables

Results

The numerical scores awarded to the dermal reactions elicited by the challenge application are shown in Table 1 (see attached background material)

The dermal reactions seen in all twenty test animals were more marked than those seen in the controls.

Clinical observations:

Dryness and sloughing of the epidermis, thickening, dryness and sloughing of the epidermis partially obscuring erythema, necrotic edge, necrotic patch, necrosis.

Applicant's summary and conclusion

Interpretation of results:

sensitising

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

In this screening test, performed in twenty albino guinea-pigs, D.I.X.T. produced evidence of delayed contact hypersensitivity in all twenty animals.

Executive summary:

Introduction:

The experimental procedure used followed the recommendations of Annex V Part B Method B6 of the EEC Directive 79/831/EEC and OECD Guideline for Testing of Chemicals No.406 "Skin sensitisation".

Method:

Thirty female albino guinea pigs of the Hartley/Dunkin strain were used in the study, 20 as test animals and 10 as control animals.

The following concentrations of DIXT were selected for the study.

Induction phase:

Intradermal injection: 1% v/v in liquid paraffin

Topical application: Neat substance as supplied

During the induction period the control animals wwere treated similarly to the test animals with the exception that the test substance was omitted from the interdermal injections and topical application.

Challenge phase:

Neat substance as 50% v/v in liquid paraffin.

Challenge exposure:

The test and control animals were challenged topically two weeks after the induction period using DlXT., as supplied and 50% v/v in liquid paraffin.

The challenge sites were evaluated 24, 48 and 72 hours after removal of the patches.

Dermal reactions in the test animals elicited by the challenge application were compared with the findings simultaneously obtained in the control animals.

 

A test animal was considered to show positive evidence of delayed contact hypersensitivity if the observed dermal reaction at challenge was definitely more marked and/or persistent than the maximum reaction seen in animals of the control group.

Results:

The dermal reactions seen in all twenty test animals were more marked than those seen in the controls.

Clinical observations observed in test group animals included:

Dryness and sloughing of the epidermis, thickening, dryness and sloughing of the epidermis partially obscuring erythema, necrotic edge, necrotic patch, necrosis.

Conclusion:

In this screening test, performed in twenty albino guinea-pigs, DIXT produced evidence of delayed contact hypersensitivity in all twenty animals and therefore requires labelling as a skin sensitiser.