Alkenes, C6-

Endpoint summary

Description of key information

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, including alkenes, C6, do not meet the quantitative criteria for classification as skin irritants.
A read-across eye irritation study (OECD 405) from alkenes, C6-8 was identified in which test material was 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

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/C11/C12/C13, alkenes, C11/C13/C14, 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, 1996(a)).

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, 1996(b)).

 

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. 

One read-across eye irritation study was identified from alkenes, C6 -8, in which 0.1 mL of SHOP C68 internal olefin was instilled the conjunctival sac of the right eye in 3 New Zealand White rabbits (Rees, 1996). Animals then were observed at 1, 24, 48, and 72 hours. Irritation was scored by the guidelines. 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. In this study, SHOP C68 internal olefin is a non-irritant to the eye.

Justification for classification or non-classification

Isomerised olefins; alpha, internal, linear and branched - multiple carbon number, including alkenes, C6 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.

Alkenes, C6 do not meet the criteria for classification as an eye irritant as defined by EU Dangerous Substances Directive 67/548/EEC or to CLP EU Regulation 1272/2008 (GHS aligned) based on read across data from alkenes, C6 -8.