Registration Dossier

Administrative data

Description of key information

Skin sensitisation (2x GPMT): not sensitising (based on Read Across with Sulfolane)

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Referenceopen allclose all

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Justification for type of information:
Skin sensitisation is standard information required for the registration of substances manufactured or imported in quantities of ten tonne per year or more. However, according to Annex XI, 1.5 of the REACH Regulation, Read-across and grouping approaches can be used to adapt the standard testing regime.
This read-across study report follows notably the recommendations made by the European Chemicals Agency in its “Guidance on information requirements and chemical safety assessment Chapter R.6 – QSARs and grouping of chemicals” (ECHA, 2008) and in its document “Read-Across Assessment Framework (RAAF)” (ECHA, 2017).

A read-across approach appears appropriate to predict the endpoint “skin sensitisation” for the substance 3-methylsulfolane because:
- Structurally the source and target chemical have clear similarities, as they are both organosulfur compounds consisting of a non-aromatic cyclic sulfone, with or without a methyl-group on the 3 position. The slight differences in physico-chemical properties are not expected to influence the dermal absorption or the potential for the skin sensitisation of these substances
- Both the source and target substances underwent predictive assessment by by using a DEREK in silico analysis for skin sensitisation, furthermore the possible metabolites were screened for their sensitising potential in the OECD QSAR toolbox. This available data was evaluated in the light of existing data and did not indicate major differences in their sensitising potential.

The attached report follows the RAAF method and so presents:
1) The hypothesis: analogue read-across approach, based on the similarity of the substances and the absence of skin sensitisation potential for these types of structures;
2) The scientific justifications (“Assessment Elements”) and their evaluation (“Assessment Options”); which demonstrate the confidence that can be put in this prediction.
3) The conclusions, usable for classification assessment or risk assessment, which are summarised hereafter.

The conclusion of the read-across assessment from the source “sulfolane” to the targetsubstance “3-methulsulfolane” is:
Substance “3-methylsulfolane” does not require a classification for Skin Sensitisation according to CLP Regulation EC/1272/2008 and its amendments.
Reason / purpose:
read-across source
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
2%
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
no indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
2%
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
no indication of skin sensitisation
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
0%
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
no indication of skin sensitisation
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Remarks on result:
other: positive control not specified
Interpretation of results:
other: not sensitising
Remarks:
in accordance with Annex I of 1272/2008/EC (CLP)
Conclusions:
The skin sensitisation potential of 3-methylsulfolane was evaluated by read across with the analogue source molecule Tetrahydrothiophene-1,1-dioxide. Based on the available information, 3-methylsulfolane does need to be classified for skin sensitisation, according to the classification criteria outlined in Annex I of 1272/2008/EC (CLP).
Executive summary:

The skin sensitisation potential of 3-methyl sulfolane was assessed by read across from the analogue source substance Tetrahydrothiophene-1,1-dioxide. Here the experimental information of the source substance is summarised.

Primary skin irritation screens – intradermal and topical application - were used to determine the concentration of test material used during the main study.  Induction: Two rows of intradermal injections were made on the shaved backs of guinea pigs (5 animals per sex per dose). Injected were 0.1 ml Freunds Complete Adjuvant (FCA) to the anterior sites; 0.1 ml 2% sulfolane in water to the middle sites; and 0.1 ml 2% sulfolane in FCA to the posterior sites). The control animals were treated with vehicle and/or FCA only. One week after induction the same area of skin was shaven and occlusively exposed to 0.2 ml undiluted sulfolane, or vehicle for 48 hours. The dermal test sites were washed with water after removal of the dressings.  Challenge: Three weeks following the intradermal phase of induction, all animals were challenged by occluded application of undiluted sulfolane in acetone for 24 hours. Afterwards the patches were removed and the challenge sites washed with water. The condition of the test sites was assessed shortly after removal of the challenge patches, and 24 and 48 hours after removal of the challenge patches. In the guinea pig sensitisation test using the method of Magnusson and Kligman, repeated administration of sulfolane did not result in skin sensitisation to guinea pigs.

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
1993
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
other: Directive 84/449/EEC, Method B.6 (skin sensitisation)
GLP compliance:
yes
Type of study:
Freund's complete adjuvant test
Justification for non-LLNA method:
An LLNA study was not performed because there is an existing reliable study for skin sensitisation using the Freund's complete adjuvant test method.
Species:
guinea pig
Strain:
Dunkin-Hartley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Harlan Porcellus
- Age at study initiation: 7-9 weeks
- Housing: up to five animals per stainless steel wire-mesh cage
- Diet: FD1, S.D.C., Special Diets Services Ltd., ad libitum
- Water: Tap water ad libitum
- Acclimation period: minimum of two weeks

ENVIRONMENTAL CONDITIONS
- Temperature (oC): 19-23oC
- Humidity (%): 30-70%
- Photoperiod (hrs dark/ hrs light): 12 hr day and 12 hr night
Route:
intradermal and epicutaneous
Vehicle:
water
Concentration / amount:
2% m/v sulfolane in water/FCA for interdermal application; undiluted sulfolane for topical application.
No.:
#1
Route:
intradermal and epicutaneous
Vehicle:
water
Concentration / amount:
2% m/v sulfolane in water/FCA for interdermal application; undiluted sulfolane for topical application.
No. of animals per dose:
10/sex (test groups); 5/sex (control group).
Details on study design:
RANGE FINDING TESTS: Primary skin irritation screens – intradermal and topical application - were used to determine the concentration of test material used during the main study. The maximum practicable concentration of the test material in the chosen vehicle was taken as 2% for intradermal application and undiluted test material for topical applications.

MAIN STUDY
A. INDUCTION EXPOSURE
Two rows of intradermal injections were made, one on either side of the mid-line, of the shaved backs of guinea pigs. In the test animals: 0.1 ml of emulsified Freunds Complete Adjuvant (FCA) to the anterior sites; 0.1 ml 2% sulfolane in water to the middle sites; and 0.1 ml 2% sulfolane in FCA to the posterior sites. For the control animals: 0.1 ml FCA to the anterior sites; 0.1 ml of water (vehicle) to the middle sites; and 0.1 ml of water (vehicle) in FCA to the posterior sites. One week after induction by intradermal injection, the same area of skin was shaven and a patch of filter paper, moistened with 0.2 ml undiluted sulfolane was placed over the intradermal sites, covered with occlusive tape and held in place by elastic adhesive bandage for 48 hours. Similar patches of filter paper moistened with the vehicle alone were applied to the control group of guinea pigs. The dermal test sites were washed with water after removal of the dressings.

B. CHALLENGE EXPOSURE
Three weeks following the intradermal phase of induction, all animals were challenged by occluded application of undiluted sulfolane in acetone for. After 24 hours, the patches were removed and the challenge sites were washed with water. The condition of the test sites was assessed shortly after removal of the challenge patches, and 24 and 48 hours after removal of the challenge patches.
Challenge controls:
The same induction procedures were carried out on a control group of five male and five female animals, except that the test material was replaced by vehicle in all doses. Challenge was identical as for test material, with application of a 75% sulfolane solution.
Positive control substance(s):
not specified
Positive control results:
No information is available.
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
2%
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
no indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
2%
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
no indication of skin sensitisation
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
0%
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
no indication of skin sensitisation
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Remarks on result:
other: Positive control not specified

Guinea pigs receiving undiluted sulfolane during the challenge phase only and those animals exposed to the same challenge dose following the induction with a single intradermal injection of 2% sulfolane in water/Freund’s adjuvant plus a topical application of undiluted sulfolane exhibited no dermal irritation at any timepoint.

Interpretation of results:
other: not senisitising
Remarks:
in accordance with Annex I of 1272/2008/EC (CLP)
Conclusions:
Under the conditions of this study, repeated administration of sulfolane did not result in skin sensitisation to guinea-pigs. Therefore the substance does not need to be classified for skin sensitisation, according to the classification criteria outlined in Annex I of 1272/2008/EC (CLP).


Executive summary:

Primary skin irritation screens – intradermal and topical application - were used to determine the concentration of test material used during the main study.  Induction: Two rows of intradermal injections were made on the shaved backs of guinea pigs (5 animals per sex per dose). Injected were 0.1 ml Freunds Complete Adjuvant (FCA) to the anterior sites; 0.1 ml 2% sulfolane in water to the middle sites; and 0.1 ml 2% sulfolane in FCA to the posterior sites). The control animals were treated with vehicle and/or FCA only. One week after induction the same area of skin was shaven and occlusively exposed to 0.2 ml undiluted sulfolane, or vehicle for 48 hours. The dermal test sites were washed with water after removal of the dressings.  Challenge: Three weeks following the intradermal phase of induction, all animals were challenged by occluded application of undiluted sulfolane in acetone for 24 hours. Afterwards the patches were removed and the challenge sites washed with water. The condition of the test sites was assessed shortly after removal of the challenge patches, and 24 and 48 hours after removal of the challenge patches. In the guinea pig sensitisation test using the method of Magnusson and Kligman, repeated administration of sulfolane did not result in skin sensitisation to guinea pigs.

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
1982
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Not GLP compliant, available as unpublished report.
Reason / purpose:
reference to same study
Qualifier:
equivalent or similar to
Guideline:
other: Guinea pig maximisation test
GLP compliance:
no
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
An LLNA study was not performed because there is an existing reliable study for skin sensitisation using the Guinea Pig Maximisation test method.
Species:
guinea pig
Strain:
Hartley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Dutchland Laboratory Animals, Inc., USA
- Weight at study initiation: 300-500 g
- Housing: Individual animal per cage
- Diet: Purina Guinea Pig Chow ad libitum
- Water: Tap water ad libitum
- Acclimation period: minimum of one week
Route:
other: epicutaneous
Vehicle:
other: acetone
Concentration / amount:
75% v/v for epicutaneous application
Route:
epicutaneous, occlusive
Vehicle:
other: acetone
Concentration / amount:
75% v/v for epicutaneous application
No. of animals per dose:
5/sex (test and negative control groups)
Details on study design:
RANGE FINDING TESTS: A primary skin irritation screen was used to determine the concentration of test material used during the main study. The maximum practicable concentration of the test material in the chosen vehicle was taken as 75% v/v for topical applications.

MAIN STUDY
A. INDUCTION EXPOSURE
A topical application of 75% sulfolane solution was applied to the shaved backs of 5 male and 5 female guinea pigs and covered by an occlusive dressing for six hours. The same induction procedures were carried out on a control group of five male and five female animals, except that the test material was replaced by the vehicle acetone. The test material and control vehicle were reapplied once per week for three weeks.

B. CHALLENGE EXPOSURE
Fifteen days following the last induction application, all animals were challenged by occluded application of 75% sulfolane in acetone for 4 to 6 hours. The condition of the test sites was assessed approximately 24, 48 and 72 hours later.
Challenge controls:
The same induction procedures were carried out on a control group of five male and five female animals, except that the test material was replaced by vehicle in all doses. Challenge was identical as for test material, with application of a 75% sulfolane solution.

Positive control substance(s):
yes
Remarks:
Dinitrochlorobenzene (DNCB) at 0.15% and 0.1% was used for the induction and challenge phases, respectively.
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
75%
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
75 %
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
other: 3rd reading
Hours after challenge:
72
Group:
test group
Dose level:
75 %
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
75%
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
75%
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
other: 3rd reading
Hours after challenge:
72
Group:
test group
Dose level:
75%
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
Dinitrochlorobenzene (DNCB) at 0.1% and 0.15%
Remarks on result:
other: See "Remarks"
Remarks:
Guinea pigs treated with 0.1% DNCB in acetone during the challenge phase only exhibited very slight erythema in 3/10 animals at 24 hours, which persisted in one animal at the 48-hr timepoint. Animals exposed to the same challenge concentration of DNCB, following the induction with 0.15% DNCB in acetone and a rest period, exhibited very slight to moderate to severe erythema at 24 hours, with persisted to some degree to the 48- and 72-hr timepoints in several animals. There was also slight edema in one animal at the 24-hr timepoint, and blanching in 4/10 animals at the 24-hr timepoint. It is concluded that the guinea pigs responded to hypersensitisation when a known sensitiser was used.

Guinea pigs receiving 75% sulfolane in acetone during the challenge phase only and those animals exposed to the same challenge dose following the induction with 75% sulfolane in acetone exhibited no dermal irritation at any timepoint.

Positive control: Guinea pigs treated with 0.1% DNCB in acetone during the challenge phase only exhibited very slight erythema in 3/10 animals at 24 hours, which persisted in one animal at the 48-hr timepoint. Animals exposed to the same challenge concentration of DNCB, following the induction with 0.15% DNCB in acetone and a rest period, exhibited very slight to moderate to severe erythema at 24 hours, with persisted to some degree to the 48- and 72-hr timepoints in several animals. There was also slight edema in one animal at the 24-hr timepoint, and blanching in 4/10 animals at the 24-hr timepoint. It is concluded that the guinea pigs responded to hypersensitisation when a known sensitiser was used.

Interpretation of results:
other: not senisitising
Remarks:
in accordance with Annex I of 1272/2008/EC (CLP)
Conclusions:
Under the conditions of this study, repeated administration of sulfolane did not result in skin sensitisation to guinea-pigs. Therefore the substance does not need to be classified for skin sensitisation, according to the classification criteria outlined in Annex I of 1272/2008/EC (CLP).
Executive summary:

A primary skin irritation screen was used to determine the concentration of Sulfolane, to be tested for its skin sensitisation potential in Guinea pigs. The maximum practicable concentration of the test material

in the chosen vehicle was taken as 75% v/v for topical applications. Induction: A topical application of 75% sulfolane solution was applied to the shaved backs of 5 male and 5 female guinea pigs (5/sex (test

and negative control groups) and covered by an occlusive dressing for six hours. The same induction procedures were carried out on a control group of five male and five female animals, except that the test

material was replaced by the vehicle acetone. The test material and control vehicle were reapplied once per week for three weeks. Challenge: Fifteen days following the last induction application, all animals

were challenged by occluded application of 75% sulfolane in acetone for 4 to 6 hours. The condition of the test sites was assessed approximately 24, 48 and 72 hours later. Guinea pigs receiving 75% sulfolane in acetone during the challenge phase only and those animals exposed to the same challenge dose following the induction with 75% sulfolane in acetone exhibited no dermal irritation at any timepoint. Thus, under the conditions of this study, repeated administration of sulfolane did not result in skin sensitisation to guinea-pigs.

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Justification for type of information:
Skin sensitisation is standard information required for the registration of substances manufactured or imported in quantities of ten tonne per year or more. However, according to Annex XI, 1.5 of the REACH Regulation, Read-across and grouping approaches can be used to adapt the standard testing regime.
This read-across study report follows notably the recommendations made by the European Chemicals Agency in its “Guidance on information requirements and chemical safety assessment Chapter R.6 – QSARs and grouping of chemicals” (ECHA, 2008) and in its document “Read-Across Assessment Framework (RAAF)” (ECHA, 2017).

A read-across approach appears appropriate to predict the endpoint “skin sensitisation” for the substance 3-methylsulfolane because:
- Structurally the source and target chemical have clear similarities, as they are both organosulfur compounds consisting of a non-aromatic cyclic sulfone, with or without a methyl-group on the 3 position. The slight differences in physico-chemical properties are not expected to influence the dermal absorption or the potential for the skin sensitisation of these substances
- Both the source and target substances underwent predictive assessment by by using a DEREK in silico analysis for skin sensitisation, furthermore the possible metabolites were screened for their sensitising potential in the OECD QSAR toolbox. This available data was evaluated in the light of existing data and did not indicate major differences in their sensitising potential.

The attached report follows the RAAF method and so presents:
1) The hypothesis: analogue read-across approach, based on the similarity of the substances and the absence of skin sensitisation potential for these types of structures;
2) The scientific justifications (“Assessment Elements”) and their evaluation (“Assessment Options”); which demonstrate the confidence that can be put in this prediction.
3) The conclusions, usable for classification assessment or risk assessment, which are summarised hereafter.

The conclusion of the read-across assessment from the source “sulfolane” to the targetsubstance “3-methulsulfolane” is:
Substance “3-methylsulfolane” does not require a classification for Skin Sensitisation according to CLP Regulation EC/1272/2008 and its amendments.
Reason / purpose:
read-across source
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
75%
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
75 %
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
other: 3rd reading
Hours after challenge:
72
Group:
test group
Dose level:
75 %
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
75%
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
75%
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
other: 3rd reading
Hours after challenge:
72
Group:
test group
Dose level:
75%
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
Dinitrochlorobenzene (DNCB) at 0.1% and 0.15%
Remarks on result:
other: See "Remarks"
Remarks:
Guinea pigs treated with 0.1% DNCB in acetone during the challenge phase only exhibited very slight erythema in 3/10 animals at 24 hours, which persisted in one animal at the 48-hr timepoint. Animals exposed to the same challenge concentration of DNCB, following the induction with 0.15% DNCB in acetone and a rest period, exhibited very slight to moderate to severe erythema at 24 hours, with persisted to some degree to the 48- and 72-hr timepoints in several animals. There was also slight edema in one animal at the 24-hr timepoint, and blanching in 4/10 animals at the 24-hr timepoint. It is concluded that the guinea pigs responded to hypersensitisation when a known sensitiser was used.

Guinea pigs receiving 75% sulfolane in acetone during the challenge phase only and those animals exposed to the same challenge dose following the induction with 75% sulfolane in acetone exhibited no dermal irritation at any timepoint.

Positive control: Guinea pigs treated with 0.1% DNCB in acetone during the challenge phase only exhibited very slight erythema in 3/10 animals at 24 hours, which persisted in one animal at the 48-hr timepoint. Animals exposed to the same challenge concentration of DNCB, following the induction with 0.15% DNCB in acetone and a rest period, exhibited very slight to moderate to severe erythema at 24 hours, with persisted to some degree to the 48- and 72-hr timepoints in several animals. There was also slight edema in one animal at the 24-hr timepoint, and blanching in 4/10 animals at the 24-hr timepoint. It is concluded that the guinea pigs responded to hypersensitisation when a known sensitiser was used.

Interpretation of results:
other: not senisitising
Remarks:
in accordance with Annex I of 1272/2008/EC (CLP)
Conclusions:
The skin sensitisation potential of 3-methylsulfolane was evaluated by read across with the analogue source molecule Tetrahydrothiophene-1,1-dioxide. Based on the available information, 3-methylsulfolane does need to be classified for skin sensitisation, according to the classification criteria outlined in Annex I of 1272/2008/EC (CLP).
Executive summary:

The skin sensitisation potential of 3-methyl sulfolane was assessed by read across from the analogue source substance Tetrahydrothiophene-1,1-dioxide. Here the experimental information of the source substance is summarised.

A primary skin irritation screen was used to determine the concentration of Sulfolane, to be tested for its skin sensitisation potential in Guinea pigs. The maximum practicable concentration of the test material

in the chosen vehicle was taken as 75% v/v for topical applications. Induction: A topical application of 75% sulfolane solution was applied to the shaved backs of 5 male and 5 female guinea pigs (5/sex (test

and negative control groups) and covered by an occlusive dressing for six hours. The same induction procedures were carried out on a control group of five male and five female animals, except that the test

material was replaced by the vehicle acetone. The test material and control vehicle were reapplied once per week for three weeks. Challenge: Fifteen days following the last induction application, all animals

were challenged by occluded application of 75% sulfolane in acetone for 4 to 6 hours. The condition of the test sites was assessed approximately 24, 48 and 72 hours later. Guinea pigs receiving 75% sulfolane in acetone during the challenge phase only and those animals exposed to the same challenge dose following the induction with 75% sulfolane in acetone exhibited no dermal irritation at any timepoint. Thus, under the conditions of this study, repeated administration of sulfolane did not result in skin sensitisation to guinea-pigs.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
Additional information:

The skin sensitisation potential of 3-methyl sulfolane was assessed by read across from the analogue source substance Tetrahydrothiophene-1,1-dioxide. Here, the experimental information of the source substance is summarised. The accompanying read across justification files are attached to the target study records.

In the first source study (Sittingbourne Research Centre, 1993), the skin sensitisation potential of sulfolane was examined in a Guinea Pig Maximisation Test performed in accordance with Directive 84/449/EEC, Method B.6 (skin sensitisation) using the method of Magnusson and Kligman. Induction: Two rows of intradermal injections were made, one on either side of the mid-line, of the shaved backs of guinea pigs. In the test animals: 0.1 ml of emulsified Freunds Complete Adjuvant (FCA) to the anterior sites; 0.1 ml 2% sulfolane in water to the middle sites; and 0.1 ml 2% sulfolane in FCA to the posterior sites. For the control animals: 0.1 ml FCA to the anterior sites; 0.1 ml of water (vehicle) to the middle sites; and 0.1 ml of water (vehicle) in FCA to the posterior sites. One week after induction by intradermal injection, the same area of skin was shaven and a patch of filter paper, moistened with 0.2 ml undiluted sulfolane was placed over the intradermal sites, covered with occlusive tape and held in place by elastic adhesive bandage for 48 hours. Similar patches of filter paper moistened with the vehicle alone were applied to the control group of guinea pigs. The dermal test sites were washed with water after removal of the dressings.

Challenge: Three weeks following the intradermal phase of induction, all animals were challenged by occluded application of undiluted sulfolane in acetone. After 24 hours, the patches were removed and the challenge sites were washed with water. The condition of the test sites was assessed shortly after removal of the challenge patches, and 24 and 48 hours after removal of the challenge patches.

Challenge controls: The same induction procedures were carried out on a control group of five male and five female animals, except that the test material was replaced by vehicle in all doses. Challenge was identical as for test material, with application of a 75% sulfolane solution. Under the conditions of this study, repeated administration of sulfolane did not result in skin sensitisation to guinea-pigs.

In the second source study (Hazleton Laboratories, 1982), A primary skin irritation screen was used to determine the concentration of Sulfolane, to be tested for its skin sensitisation potential in Guinea pigs. The maximum practicable concentration of the test material in the chosen vehicle was taken as 75% v/v for topical applications.  Induction: A topical application of 75% sulfolane solution was applied to the shaved backs of 5 male and 5 female guinea pigs (5/sex (test and negative control groups) and covered by an occlusive dressing for six hours. The same induction procedures were carried out on a control group of five male and five female animals, except that the test material was replaced by the vehicle acetone. The test material and control vehicle were reapplied once per week for three weeks.  Challenge: Fifteen days following the last induction application, all animals were challenged by occluded application of 75% sulfolane in acetone for 4 to 6 hours. The condition of the test sites was assessed approximately 24, 48 and 72 hours later.

Guinea pigs receiving 75% sulfolane in acetone during the challenge phase only and those animals exposed to the same challenge dose following the induction with 75% sulfolane in acetone exhibited no dermal irritation at any timepoint. Thus, under the conditions of this study, repeated administration of sulfolane did not result in skin sensitisation to guinea-pigs.

Justification for classification or non-classification

Based on the available information, 3-methyl sulfolane does not need to be classified for skin sensitisation in accordance with the criteria outlined in Annex I of the CLP Regulation (1272/2008/EC).


Route: .live1