Ethyl methyl sulphide

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

issued on 30-APR-2004

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2004

Report date:

2004

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Deviations:

no

GLP compliance:

yes

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

Study performed before implementation of REACH regulation.

Test material

Test material information

Constituent 1

Reference substance name:

Ethyl methyl sulphide

EC Number:

210-868-4

EC Name:

Ethyl methyl sulphide

Cas Number:

624-89-5

Molecular formula:

C3H8S

IUPAC Name:

(methylsulfanyl)ethane

Details on test material:

- Name of test material (as cited in study report): methyl ethyl sulfide
- Molecular formula (if other than submission substance): C3H8S
- Molecular weight (if other than submission substance): 76.16 g
- Smiles notation (if other than submission substance): C(SC)C
- InChl (if other than submission substance): InChI=1/C3H8S/c1-3-4-2/h3H2,1-2H3
- Substance type: pure active substance
- Physical state: colorless liquid
- Stability under test conditions: data not available
- Storage condition of test material: at room temperature and protected from light

In vivo test system

Test animals

Species:

guinea pig

Strain:

Hartley

Sex:

male/female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories France, L’Arbresle, France.
- Age at study initiation: on day 1, the animals of the main test were 1-2 months old
- Weight at study initiation: on day 1, the animals of the main test had a mean body weight ± standard deviation of 513 ± 34 g for the males and 442 ± 26 g for the females.
- Housing: during the acclimation period and throughout the study, the animals were housed individually in polycarbonate cages with stainless steel lid (48 cm x 27 cm x 20 cm) equipped with a polypropylene bottle.
- Diet: free access to 106 pelleted diet
- Water: drinking water filtered by a FG Millipore membrane (0.22 micron) was provided ad libitum.
- Acclimation period: at least 5 days before the beginning of the study.


ENVIRONMENTAL CONDITIONS
- Temperature: 22 ± 2°C
- Humidity: 30 to 70%
- Air changes: approximately 12 cycles/hour of filtered, non-recycled air.
- Photoperiod: light/dark cycle 12 h/12 h


IN-LIFE DATES: From 18-DEC-2003 to 16-FEB-2004

Study design: in vivo (non-LLNA)

Induction

Induction 1

Route:

intradermal and epicutaneous

Vehicle:

other: corn oil (intradermal injection), a mixture ethanol/water (80/20, w/w) for the induction phase (topical) and acetone for the challenge application

Induction 2

Concentration / amount:

induction by intradermal injection: 5%
induction by topical application: undiluted
challenge application: 50%

Challenge

Challenge 1

Route:

epicutaneous, occlusive

Vehicle:

other: corn oil (intradermal injection), a mixture ethanol/water (80/20, w/w) for the induction phase (topical) and acetone for the challenge application

Challenge 2

Concentration / amount:

induction by intradermal injection: 5%
induction by topical application: undiluted
challenge application: 50%

No. of animals per dose:

control group: 5 males and 5 females
test group: 10 males and 10 females

Details on study design:

RANGE FINDING TESTS:
A preliminary test was conducted in order to determine the concentrations to be tested in the main study.
- By intradermal route:
> tested concentrations: 10% and 5% (w/w)
> local reactions were evaluated approximately 24, 48 hours and 6 days after the injections.
- By cutaneous route and under the conditions of the induction phase:
> tested concentrations: 100% and 50% (w/w)
> cutaneous reactions were evaluated 24 and 48 hours after removal of the dressing.
- By cutaneous route and under the conditions of the challenge phase:
> tested concentrations: 100% and 50% (w/w)
> cutaneous reactions were evaluated 24 and 48 hours after removal of the dressings.


MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 6 intradermal injection on Day 1 and 1 topical application on Day 8
- Exposure period: once for the intradermal injections and 48h for the topical application
- Test groups:
> On Day 1, three injections of 0.1 mL were made into each side of this interscapular region:
- FCA at 50% (v/v) in 0.9% NaCl
- test item at 5% (w/w) in corn oil
- test item at 5% (w/w) in the mixture FCA/0.9% NaCl (50/50)
> On Day 8, a pad of filter paper (approximately 8 cm2) was fully-loaded with the undiluted test item
(As the test item was shown to be irritant during the preliminary test, a topical application of sodium lauryl sulfate was not necessary on day 7)
- Control group:
> On Day 1, three injections of 0.1 mL were made into each side of this interscapular region:
- FCA at 50% (v/v) in 0.9% NaCl
- corn oil
- vehicle at 50% (w/v) in a mixture FCA/0.9% NaCl (50/50)
> On Day 8, the animals of the control group received an application of the vehicle alone
- Site: interscapular area
- Frequency of applications: once on day 1 and on day 8
- Duration: from day 1 to day 8 of the study
- Concentrations: 5% for the intradermal injection and undiluted for the topical application


B. CHALLENGE EXPOSURE
- No. of exposures: one
- Day(s) of challenge: day 22
- Exposure period: 24 hours
- Test groups: 50% methyl ethyl sulfide in acetone (right flank) and vehicle alone (left flank)
- Control group: 50% methyl ethyl sulfide in acetone (right flank) and vehicle alone (left flank)
- Site: posterior right and left flanks
- Concentrations: 50% methyl ethyl sulfide
- Evaluation: 24 and 48 hours after removal of the dressing of the challenge application

Positive control substance(s):

yes

Remarks:

Mercaptobenzothiazole (CIT study No. 26182 RDG - September 2003)

Results and discussion

Positive control results:

In a recent study performed under CIT experimental conditions, the strain of guinea pigs used showed a satisfactory sensitization response in 100% animals.

In vivo (non-LLNA)

Results

Results 1

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

50%

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

none

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: 50%. No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: none.

Results 2

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

50%

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

none

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 50%. No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: none.

Results 3

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

50%

No. with + reactions:

1

Total no. in group:

20

Clinical observations:

No systemic clinical signs and no deaths were noted during the study

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 50%. No with. + reactions: 1.0. Total no. in groups: 20.0. Clinical observations: No systemic clinical signs and no deaths were noted during the study.

Results 4

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

50%

No. with + reactions:

1

Total no. in group:

20

Clinical observations:

No systemic clinical signs and no deaths were noted during the study

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 50%. No with. + reactions: 1.0. Total no. in groups: 20.0. Clinical observations: No systemic clinical signs and no deaths were noted during the study.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

According to the maximization method of Magnusson and Kligman, the test item METHYL ETHYL SULFIDE should not be considered as a skin sensitizer.

Executive summary:

The potential of the test item METHYL ETHYL SULFIDE to induce delayed contact hypersensitivity was evaluated in guinea pigs according OECD testing guideline 406 and GLP.

30 guinea pigs were allocated to two groups: a control group of five males and five females and a treated group of ten males and ten females.

On day 1, three pairs of intradermal injections were performed in the interscapular region of all animals:

- Freund's complete adjuvant (FCA) diluted to 50% (v/v) with 0.9% NaCl (both groups),

- test item at the concentration of 5% in corn oil (treated group) or vehicle alone (control group),

- test item at the concentration of 5% in a mixture FCA/0.9% NaCl (50/50, w/w) (treated group) or vehicle at the concentration of 50% (w/v) in a mixture FCA/0.9% NaCl (50/50, v/v) (control group).

On day 8, the animals of the treated group received a topical application of the undiluted test item to the same test site, which was then covered by an occlusive dressing for 48 hours. The animals of the control group received an application of the vehicle under the same experimental conditions.

On day 22, all animals of both groups were challenged by a cutaneous application of the test item at the concentration of 50% (w/w) in acetone to the right flank. The test item was maintained under an occlusive dressing for 24 hours. The vehicle was applied to the left flank under the same experimental conditions.

Skin reactions were evaluated approximately 24 and 48 hours after removal of the dressing.

No systemic clinical signs and no deaths were noted during the study.

After the challenge application, no cutaneous reactions were observed in the animals of the control group. In the treated group, a discrete erythema was noted on the right treated flank of 1/20 animals at the 24 and 48-hour readings. A discrete erythema was also recorded on the left control flank of 1/20 animals, at the 24-hour reading only.

The persistent cutaneous reactions observed in 1/20 animals of the treated group may be attributable to delayed contact hypersensitivity. However, as this possible positive reaction occurred in a single animal, the test item should not be considered as a skin sensitizer.