2-mercaptoethanol

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP and guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1994

Report date:

1994

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

GLP compliance:

yes (incl. QA statement)

Remarks:

testing lab.

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

This study was conducted before the in-vitro testing became a requirement in 2016. This in-vivo skin sensitization study meet the requirements set out in Article 13(3) first subparagrahp, and Article 13(4) and shal be considered appropriate to address this standard information.

Test material

Test material information

Constituent 1

Reference substance name:

2-mercaptoethanol

EC Number:

200-464-6

EC Name:

2-mercaptoethanol

Cas Number:

60-24-2

Molecular formula:

C2H6OS

IUPAC Name:

2-sulfanylethan-1-ol

Details on test material:

purity 99.85%

In vivo test system

Test animals

Species:

guinea pig

Strain:

Dunkin-Hartley

Sex:

male/female

Details on test animals and environmental conditions:

Sex: 15 females and 15 malesAcclimatization: at least 5 daysMean weight at study initiation: males 328 g, females 343 gHousing during acclimatization and study period: animals housed individually, temperature 19-25°C, relative humidity 30-70%, light dark cycle 12h/12hDiet (GP sustenance reference 106) and filtered tape water (filter 0.22 μm) ad libitum, no contaminants (analysed) in water, diet, or sawdust.

Study design: in vivo (non-LLNA)

Induction

Induction 1

Route:

other: first induction:intracutaneous; 2nd induction: occlusive epicutaneous

Vehicle:

physiological saline

Induction 2

Concentration / amount:

1st induction: 0.1% intracutaneous, 2nd induction: 10% occlusive epicutaneous, 3rd challenge: 25% occlusive epicutaneous

Challenge

Challenge 1

Route:

epicutaneous, occlusive

Vehicle:

physiological saline

Challenge 2

Concentration / amount:

1st induction: 0.1% intracutaneous, 2nd induction: 10% occlusive epicutaneous, 3rd challenge: 25% occlusive epicutaneous

No. of animals per dose:

Number of TS treated animals: 10 males and 10 femalesNumber of controls: 5 males and 5 females

Details on study design:

PRETEST- The minimum irritant concentration was determined by intradermal injection of increasing concentrations (volume 0.1 ml).- The minimum irritant concentration and the max. non-irritant concentration were determined by cutaneous application of increasing concentrations (volume 0.5 ml).ADMINISTRATION/EXPOSURE MAIN STUDY- Preparation of TS for intradermal induction: 0.1% TS in vehicle (0.9% aqueous NaCl) resp. in Freund's adjuvant/0.9% aqueous NaCl solution (1:1).- Preparation of TS for percutaneous induction: 10% TS in vehicle (non-irritant concentration).- Preparation of TS for challenge: 25% TS in aqua bidest. (non-irritant concentration)- Intradermal induction schedule on day 1: total of 6 intradermal injections (a) 2 injections each of 0.1 ml Freund's adjuvant with 0.9% aqueous NaCl-solution (1:1) without TS (left and right shoulder; (b) 2 injections each of 0.1 ml 0.1% TS in 0.9% NaCl; (c) 2 injections each of 0.1 ml 0.1% TS in Freund'sadjuvant/0.9% NaCl (1:1)Controls: same exp. design without TS: - On day 7 all animals treated cutaneously with 0.5 ml of sodium laurylsulphate in vaseline to provoke irritation- Percutaneous induction on day 8: application of 0.5 ml 10% TS in vehicle; controls received 0.5 ml of the vehicle. Test volume on a dry compress, which was held in place for 48 h by an occlusive dressing.- Challenge schedule on day 22 for treatment and control group: 0.5 ml of 25% TS on the right flank and 0.5 ml vehicle on the left flank; occlusive dressing for 24 h; scoring of cutaneous reactions 24 and 48 h after removal of the dressing.- Positive control: 1-chloro-2,4-dinitrobenzene tested on 5 females ca. 2 months before the main study was started; induction: 0.05% intradermal on day 1, 0.5% cutaneous route on day 8; challenge: 0.1% right flank and 0.5% left flankThe animals were observed twice a day during the study in order to record clinical signs and to check for mortality.The animals were weighed individually on the day of allocation into the groups, on the first day of the study (day. 1), then on days 8, 15 and 25.On day 25, after the 48-hotir observation period, the animals were sacrificed by CO2 inhalation in excess.On day 25, a skin sample was taken from the treatment sites of the posterior left and right flanks of all animals. The samples were preserved in 10% buffered formalin.No histological examinations were performed .

Positive control substance(s):

yes

Results and discussion

Positive control results:

RESULTS OF THE PILOT STUDY:- minimum irritant concentration after intradermal injection: 0.1% (no necrosis)- 10 or 25% resulted in no erythema or edema; the max. non-irritant concentration is 25% TS in vehicle RESULTS OF MAIN TEST:- No clinical signs or mortality- No effect on body weight gain (determined on day 1, 8, 15, 25)- On day 10 (end of induction period) irritation in control and treated groups were observed at the intradermal injection sites- Challenge resulted in no skin reaction in controls but erythema score 2 in 4 males and 3 females and erythema score 1 in all other animals of the treatment group 24 h after challenge- Sensitization reaction in treated animals:Control group 0/10Test group males & females 8/20- valid positive control (positive reaction in 5/5)

In vivo (non-LLNA)

Results

Reading:

other: challenge

Hours after challenge:

24

Group:

test chemical

Dose level:

0.5 ml of a 25% solution

No. with + reactions:

8

Total no. in group:

20

Clinical observations:

erythema score 2 for seven animals and erythema score 1 for all other animals

Remarks on result:

other: see Remark

Remarks:

Reading: other: challenge. . Hours after challenge: 24.0. Group: test group. Dose level: 0.5 ml of a 25% solution. No with. + reactions: 8.0. Total no. in groups: 20.0. Clinical observations: erythema score 2 for seven animals and erythema score 1 for all other animals.

Applicant's summary and conclusion

Interpretation of results:

sensitising

Remarks:

Migrated information

Conclusions:

According to the maximization method cutaneous reactions attributable to the sensitization potential of the test substance were observed in 40% of tested guinea-pigs. The allergenicity level is moderate.