(4S)-1-methyl-4-(6-methylhepta-1,5-dien-2-yl)cyclohexene

Endpoint summary

Additional information

Skin irritation

No key study for skin irritation/corrosion is available for beta-bisabolene. In a study in Vienna White rabbits - not performed according to current guidelines - Bisabolene (unknown isomer composition) was dermally applied undiluted for 24 hours on 6 animals under occlusive conditions (BASF 1979; 77/442). Occlusive dermal application resulted in skin irritation and mean erythema and edema scores (24h, 48h and 72h timepoints per animal; mean of all animals) of 2.2 and 1.8, respectively. The reversibility of skin irritation within 14 days has not been assessed in this study, since the animals were monitored for 72 hours only. Furthermore, the exposure conditions chosen (i.e. occlusive application for 24 hours) represent a worst case when compared to current test guidelines. 

In a skin irritation study according to OECD TG 404, a mixture was tested, that contained different isomers of Bisabolene as main components (i.e. alpha-, gamma-Bisabolene) with high structural similarity to beta-Bisabolene as well as beta-biabolene, which was also present at lower concentrations in the test substance applied (RCC 2002; 845132). The test substance was applied undiluted for 4h to the intact left flank of each of 3 New Zealand White rabbits under semiocclusive conditions. The scoring of skin reactions was performed 1, 24, 48 and 72 hours, as well as 7, 10 and 14 days after removal of the dressing.

The application of the test substance resulted in moderate/severe and prolonged signs of irritation such as erythema, oedema and scaling. Both the erythema and oedema were reversible and were no longer evident at termination of the test. The mean erythema score of the three animals (24, 48 and 72 hours after patch removal for each animal) was 3.00, 2.67 and 2.33, respectively and the mean oedema score was 1.00, 1.00 and 1.33, respectively. No corrosive effects were noted on the treated skin of any animal at any of the measuring intervals.

When considering the two studies available for Bisabolene in a weight of evidence approach, beta-Bisabolene is considered to show skin irritating properties. 

 

Eye irritation

In the chosen key study for eye irritation, 0.1 ml Bisabolene (unknown isomer composition) was applied undiluted to the conjunctival sac of the right eye of 6 Vienna White rabbits (BASF 1979; 77/442). The application resulted in mean scores (24h, 48h and 72h timepoints per animal; mean of all animals) of 0.0, 0.0, 0.8 and 0.0 for corneal opacity, iritis, conjunctival redness and chemosis, respectively. Thus, a slight eye irritation potential was observed under the chosen testing conditions. Although animals were not followed up to assess the reversibility of the conjunctival redness (up to 21 days), a reduction in the severity was observed 24 hours after application (compared to the 1h timepoint) and 3 of 6 animals were free of symptoms 72 hours after application. Thus, a full reduction of these effects within 21 days is very likely. 

Overall, the study data available for Bisabolene provide evidence, that beta-Bisabolene is considered to show no eye irritating properties. 

 

Justification for classification or non-classification

The present data on skin irritation do fulfill the criteria laid down in regulation (EU) 1272/2008, and a classification as "skin irritant" (category 2) is warranted.

The present data on eye irritation do not fulfill the criteria laid down in regulation (EU) 1272/2008, and therefore, a non-classification is warranted.