Methyl 2,6,6-trimethylcyclohex-2-ene-1-carboxylate

Endpoint summary

Description of key information

Read-Across (analogue): non-sensitising, Guinea Pig (male), eq. to OECD TG 406, 1992

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

OECD TG 406 GPMT 1992: GPMT; Read-across – The study was performed according to a method equivalent to guideline OECD TG 406 consistent with Magnusson-Kligman maximisation test to assess the skin sensitisation potential of the test substance. The study was conducted using a preliminary irritation screen, a two-stage induction phase and a challenge phase with a rechallenge. Preliminary irritation testing was used to define the doses in the induction phases of the study and the challenge phase of the study. 14 days after the induction period, a challenge dose of the undiluted test substance selected for application to the left flank on each test animal; and 50% v/v in ethanol applied to the right flank using the same procedure as in the topical induction. The site was inspected at 24 and 48 hours and due to dislodging of the application patches beneath the occlusive dressing a rechallenge was initiated 24hours after the first challenge. Again 3 hours into the second challenge dislodging occurred and so fresh application patches applied. Following the first challenge application no response was observed at either challenge dose. The overall sensitisation rate was 0%. No responses were exhibited in any member of the test group (undiluted, 100% v/v) or control group. Following the second challenge using 50%v/v concentration in the test group two responses were exhibited (scored 1). No responses were seen in the control group. The overall sensitisation rate was 10%. Since the overall response rate both in the challenge and rechallenge was < 30 %, under the conditions of this study the test substance is not a contact skin sensitizer.

Justification for selection of skin sensitisation endpoint:

One GLP compliant guideline GPMT study available on structural analogue Klimisch 2. Selected study is an in vivo study indicating negative reaction to dermal exposure at the highest dose level tested.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

The substance does not meet classification criteria under Regulation (EC) No 1272/2008 for skin sensitisation.

In the GPMT test on an analogue substance: following 25%v/v intradermal induction with 100%v/v topical booster; the severity of effects upon rechallenge were limited (score = 1) and low response rate (10%) at 50% v/v in ethanol vehicle. These responses were not seen in the highest dose level (100% v/v). In the highest dose level responses were non-existent (score = 0) and within a parallel negative control. The test was consistent with established adjuvant-test methodology with a minor deviation that may have predisposed irritant false-positives during challenge. Under EU criteria no significant effects were observed (> 30% response rate) in the in vivo GPMT study on exposure to the substance at > 1% v/v intradermal induction dose. The target substance cannot be considered a skin sensitizer.