Dodecene

Endpoint summary

Description of key information

No key skin irritation studies were available for isomerised olefins; alpha, internal, linear and branched - single carbon number, including dodecene. Six key skin irritation studies (OECD 404) were identified for isomerised olefins; alpha, internal, linear and branched - multiple carbon number. The available data indicate that C6-8 to C20-24 isomerised olefins do not meet the quantitative criteria for classification as skin irritants. Two read-across eye irritation studies (OECD 405) from isomerised olefins; alpha, internal, linear and branched – multiple carbon numbers were identified. Both studies found the test material to be not irritating to the eyes of rabbits.

Key value for chemical safety assessment

Skin irritation / corrosion

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Additional information

No skin irritation studies were available for isomerised olefins; alpha, internal, linear and branched – single carbon number; however eleven skin irritation studies were identified for isomerised olefins; alpha, internal, linear and branched-multiple carbon number. For the purpose of hazard identification, only six of these were considered key (Klimisch scores =1) because they adhered to the current OECD 404 guidelines (4 hour exposure, semi-occlusive conditions) with mean scores for erythema and oedema averaged over 24, 48, and 72 hours. These six studies were conducted with the following substances: alkenes, C6-8, alkenes, C10-13, alkenes, C11/13/14, alkenes, C16-18, and alkenes, C20-24. The remaining studies, using occlusive methods and/or skin contact times exceeding 4 hours duration, were considered less reliable since the exposure conditions were more stringent than guideline and likely therefore to yield unrepresentative results.  

 

The application of alkenes, C6-8 as SHOP C68 internal olefin, to rabbit skin produced very slight to slight erythema, which sometimes extended beyond the test site, and occasionally very slight oedema for the first 72 hours post exposure. The mean erythema and oedema scores were 1.55 and 0, respectively (Rees, 1996a).

 

Treatment of rabbit skin with alkenes, C10 /C11/C12/C13, applied as SHOP olefin 103, produced slight-to-moderate reversible irritation in a majority of animals, with more pronounced responses present in two of six rabbits at day 7 which then fully resolved by day 16 (flaking skin at test site). The mean erythema score was 1.7 over 72 hours and the mean oedema score was 0.5 (Price, 1985).

 

Very slight to slight erythema and very slight oedema was observed in rabbits treated with SHOP C134 (alkenes, C11/C13/C14). Very slight oedema was still apparent in one animal 7 days post-exposure. Irritant effects were fully reversible in all animals by day 13 (Rees, 1996b).

 

Rabbits treated with alkenes, C16-18 exhibited reversible, well-defined erythema and very slight to slight oedema. The average erythema score was 1.56 over 72 hours and the average oedema score was 0.22(Morris, 1994).

 

Two studies were identified for alkenes, C20-24. In the first study, application of alkenes, C20-24 to rabbit skin produced no signs of dermal irritation in any of the treated animals; mean irritation scores erythema and oedema were 0 at all time points(Driscoll, 1998). In the second study by Sanders (2008), the mean erythema and oedema scores averaged over the 24, 48, and 72-hour observation points, were 0.33 and 0.0, respectively, when rabbit skin was exposed to alkenes, C20-24.

 

Effects recorded in the aforementioned studies were generally slight to moderate or occasionally moderate to severe irritation, however the magnitude of the responses obtained was not such that it would trigger classification as “irritating to skin” (mean erythema or oedema scores =2 or = 2.3, respectively, as described in EU Dangerous Substances Directive 67/548/EEC and CLP EU Regulation 1272/2008 (GHS aligned)). Based on a weight of evidence analysis, the available data indicate that C6 to C24 isomerised olefins are only mildly irritating to skin. Prolonged or occluded exposures in non-guideline studies (not discussed above) were in some instances associated with erythema and/or oedema suggesting that irritation may be triggered following prolonged or repeated skin contact. Precautionary classification with R66 (Repeated exposure may cause skin dryness or cracking) under the Dangerous Substances Directive or H066 (Repeated exposure may cause skin dryness or cracking) under the CLP Regulation would therefore seem reasonable.

 

There was no evidence of corrosive effects in any of these investigations. 

There were no eye irritation studies available for single carbon number isomerised olefins; therefore data from isomerised olefins; alpha, internal, linear and branched – multiple carbon numbers were used to read across for this endpoint. Two studies were selected for read across: alkenes, C6 -8 (Rees, 1996) and alkenes, C11/C13/C14 (Rees, 1996). In the acute eye irritation study conducted with alkenes, C6 -8, three New Zealand White rabbits (sex note specified) were instilled with 0.1millilitre of Shop 68 in the right eye. Initial instillation of the test compound caused very slight initial pain response. All animals had very slight to slight conjunctivitis within an hour of treatment, but one animal showed persistent response at 48 hours. At 72 hours, all animals’ eyes appeared normal. The study authors concluded that under the study conditions, SHOP C68 internal olefin was a non-irritant to the eye.

In a similar study conducted with alkenes, C11/C13/C14, three New Zealand White rabbits (sex note specified) were instilled with 0.1mL of Shop 134 in the right eye. Very slight to slight conjunctivitis was observed in all animals one hour after exposure. Very slight conjunctival redness persisted in one animal and was observed at the 24- and 48-hour examinations. Iritis was observed in one animal at the 1-hour examination. At the 72-hour examination, there were no signs of ocular irritation. None of the animals exhibited a pain response to administration of the test material. Based on these results, SHOP C134 was considered to be a non-irritant to the rabbit eye.

Results from both of these studies indicate that multiple carbon number isomerised olefin do not produce significant ocular irritation in rabbits. Based on the read across strategy used for single carbon number isomerised olefin, classification and labelling for eye irritation effects is not required for single carbon number isomerised olefin based on the lack of significant eye irritation effects observed in experiments with multiple carbon number isomerised olefins.

Justification for Read Across:

Several criteria justify the use of the read across approach to fill data gaps for single carbon number isomerised olefins using tridecene as an analogue. Tridecene is a single carbon number isomerised olefin; however, it is not a substance included under the Higher Olefins and Poly Alpha Olefins Consortium. However, tridecene’s chemical structure, physico-chemical properties, and mammalian health endpoints are comparable with other single carbon number isomerised olefins. Therefore, read across between tridecene and single carbon number isomerised olefin can be justified.

 

Several criteria justify the use of the read across approach to fill data gaps for single carbon number isomerised olefin substances using multiple carbon number isomerised olefin substance analogues. Studies indicate that changing the carbon number, the location of the double bond, or adding branching does not measurably alter the effects on mammalian health endpoints. There is a consistent toxicity potency pattern for isomerised olefins with a range of carbon numbers and they are considered to have minimal acute toxicity potential. Genotoxicity studies indicate that these materials are not mutagenic. No adverse systemic toxicity was observed in a 90-day repeated oral dose study in which rats were exposed to alkenes, C20-24. The toxicological profile of multiple carbon number isomerised olefin alkenes described above indicates a low hazard potential for human health. Since multiple carbon number isomerised olefin alkenes is comprised of a mixture of single carbon number isomerised olefins, no significant toxicological differences are expected between the two categories of substance and read across between these two categories can be justified.

Justification for classification or non-classification

Isomerised olefins; alpha, internal, linear and branched - single carbon number, including dodecene, and isomerised olefins; alpha, internal, linear and branched - multiple carbon number do not meet the criteria for classification and labelling as skin irritants under EU Dangerous Substances Directive 67/548/EEC or CLP EU Regulation 1272/2008 (GHS aligned) based on evaluation of the overall mean erythema and oedema scores from skin irritation studies with these substances. Precautionary classification with R66 (Repeated exposure may cause skin dryness or cracking) under the Dangerous Substances Directive or H066 (Repeated exposure may cause skin dryness or cracking) under the CLP Regulation is recommended.

Dodecene does not meet the criteria for classification as an eye irritant as defined by EU Dangerous Substances Directive 67/548/EEC or CLP EU Regulation 1272/2008 (GHS aligned) based on a lack of observed eye irritant effects in rabbits.