2-(morpholinothio)benzothiazole

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

Non-human information

The sensitisation potential of the test substance MBS was evaluated in a guinea pig assay, a modification of the Buhler's method (Wang 1988). The test substance was applied at a concentration of 5 % in petrolatum to the shaved skin of guinea pigs (10 animals per dose group) for induction. The test material was removed 24 h after application and readings were performed 1h after removal of the test material. This procedure was repeated 3 times a week for 2 weeks. Two weeks after the final induction application, the challenge test was performed. The left flank of the test animal was shaved, and 0.1 %, 0.5 % and 2 % dose preparations of the test material were used for challenge. The test material was removed 24 h after application and readings were performed 1 h, 24 h, 48 h and 7 d after removal of the test material. The test substance induced a dose dependent sensitizing reactions at concentrations of 0.5 % (5/10) and 2 % (10/10). No effects were noted at the lowest concentration (0.1 %, 0/10).

Thus, the findings of the guinea pig assay indicated a sensitizing potential of the test substance in animals.

Human information

The test substance MBS was evaluated in a human Repeated Insult Patch test (modified Shelanski method) with 49 volunteers (Monsanto 1982). The chemical was tested as a 75 % preparation in petrolatum. 200 mg of the test substance was placed in contact with a selected site on the back of each subject for 24 hours. Following this exposure, the test material was removed and the reaction of the site of application was evaluated and graded (score 0 through 4) by the clinical investigator. The test material was applied in this manner for four consecutive 24 hour periods each weak (monday through friday) for three consecutive weeks (induction phase). Subjects were then allowed a two week rest period, during which no exposures to the test material occurred. The sixth week was scheduled for the challenge applications. Because of the large number of panellists who had responded intensely to contact with the test material, the investigator decided to terminate the test sample applications. For the challenge applications, therefore, petrolatum alone was applied in lieu of the test sample.

The test material elicited irritation in thirty-one individuals. This was well over 50 percent of the panellists participating in this study. Although minimal or moderate erythema was the extent of irritation in seven of these individuals, the picture in the remaining twenty-four individuals was quite different. In all of these individuals, intense or very intense irritation, consisting of erythema, induration, weeping and extension beyond the margin of the contact site, was observed. The characteristics of these responses were consistent with that of a sensation effect.

Thus, after repeated treatment with the 75 % test substance preparation 24/49 volunteers showed an allergic reaction. Moreover, the allergic potential of MBS preparations was confirmed in additional Repeated Insult Patch Test with human volunteers (Monsanto 1986abc).

Migrated from Short description of key information:
The skin sensitisation potential of MBS was evaluated in guinea pigs and in studies with human volunteers. Skin sensitization was noted in guinea pigs after treatment with MBS (Wang 1988). Moreover, a clear allergic response (24/49) was noted in a Repeated Insult Patch test with human volunteers (Monsanto Co. 1982). This finding was confirmed by further Repeated Insult Patch test with human volunteers (Monsanto Co 1986abc). Thus, based on the findings of the guinea pig test and the human Repeated Insult Patch-test studies, the test substance MBS is considered to be a skin sensitizer in humans. In consequence, an existing classification with R43 (24 ATP)/ skin sensitizer cat. 1 (regulation no. 1272/2008 GHS) is confirmed.

Respiratory sensitisation

Endpoint conclusion

Additional information:

No data available.

Justification for classification or non-classification

The test substance MBS is classified as skin sensitizer according to the classification criteria 67/548/EWG and regulation no. 1272/2008 (GHS).