Octane-1-thiol

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

One key study in guinea pigs was identified to evaluate the skin sensitising potential of octane-1-thiol.

In a key guinea pig maximisation study (De Jouffrey, 1995; Klimisch score = 1) Dunkin-Hartley guinea pigs (10/sex) were exposed to octane-1-thiol in paraffin oil. The sensitization potential of the test substance was evaluated after a 10-day induction period during which time the animals were treated with paraffin oil (control group) or the test substance (treated group). On day 1, in presence of Freund's complete adjuvant, 0.1 ml of the test substance at a concentration of 1% (w/w) in the vehicle was administered by intradermal route. On day 8, 0.5 ml of the test substance in its original form was applied by cutaneous route during 48 hours by means of an occlusive dressing. After a period of 12 days without treatment, a challenge cutaneous application of 0.5 ml of the vehicle (left flank) and 0.5 ml of the test substance at a concentration of 75% (v/v) in the vehicle (right flank) were administered to all animals. The test substance and the vehicle were prepared on a dry gauze pad then applied to the skin and held in place for 24 hours by means of an occlusive dressing. Cutaneous reactions on the challenge application sites were then evaluated 24 and 48 hours after removal of the dressing. After the final scoring period, the animals were killed and cutaneous samples were taken from the challenge application sites from all animals. No histological examination was performed on the cutaneous samples.

 

No clinical signs or mortalities were observed during the study. The body weight gain of the treated animals was normal when compared to that of the control animals. In the treated group, 24 hours after removal of the dressing, very slight, well-defined and moderate to severe erythema (grades 1, 2 and 3) was observed in 8/20,8/20 and 1/20 animals, respectively. Forty-eight hours after removal of the dressing, very slight and well-defined erythema was observed in 10/20 and 7/20 animals, respectively. Dryness of the skin was noted in 11 animals. Reactions attributable to a sensitising effect (well-defined or more marked erythema) were seen in 45% of the animals. Under the conditions of this study, octane-1-thiol is considered to be dermal sensitiser.

 

In a supporting non-guideline study conducted in guinea pigs (Pence, 1983a; Klimisch score = 1) exposure to octane-1-thiol was not observed to produce any skin sensitization.

 

Skin sensitising properties of the heavy mercaptans range from non-sensitising to sensitising. Strucutral analogs such as 1,1-dimethylheptanethiol and tert-dodecanethiol are known to be weak sensitisers while dodecane-1-thiol is not a skin sensitiser. While weight of evidence from the structural analogs indicates that most of the heavy mercaptans are not classified for skin sensitisation, results from a key guideline study (OECD 406) that tested octane-1-thiol suggest that this substance is a dermal sensitizer.

Migrated from Short description of key information:
Key data from a guinea pig maximisation study were available to evaluate the skin sensitising potential of octane-1-thiol. Based on reactions attributable to a sensitising effect (well-defined or more marked erythema) observed in 45% of test animals, octane-1-thiol is considered to be a skin sensitiser.

Respiratory sensitisation

Endpoint conclusion

Additional information:

No respiratory sensitisation data is available for octane-1-thiol.

Migrated from Short description of key information:
No respiratory sensitisation data is available for octane-1-thiol.

Justification for classification or non-classification

Octane-1-thiol is classified as Category 1 (Warning; H317: May cause an allergic skin reaction) under the EU CLP regulation and R43 (Xi; May cause sensitisation by skin contact) under the EU DSD regulation.