1-Dodecene, mixed with 1-decene and 1-octene, dimers, hydrogenated

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

Skin sensitisation

No skin sensitisation data were found for the registered substance. However, several studies are available on the skin sensitization potential of structurally analogous substances. In total, one study was identified for 1-decene dimer, hydrogenated and two studies identified for 1-dodecene dimer, hydrogenated. All of the animal studies were performed in a manner similar or equivalent to currently established OECD test guideline 406.  Summaries of these studies are presented below. Together, these studies support the conclusion that the registered substance is not a dermal sensitiser.

A Buehler sensitisation study (Chevron, 1994b) was identified for 1-decene dimer, hydrogenated. Following a pilot study to determine the appropriate concentrations of test material to use in the induction and challenge phases, male and female guinea pigs were dermally treated with undiluted test material once /week for 6 hours for three consecutive weeks.  Following a 2 week rest period, the test animals and a naïve control group were dermally challenged with 5 % test substance w/v in spectrum oil. The animals were scored for skin sensitising reactions at 24 and 48 hours following the challenge phase.  A grade 1 response generally indicates sensitization, provided grades of less than 1 are seen in the respective control animals.  The incidence of grade 1 responses in the test group was 5 of 20 at 24h and 0 out of 20 at 48 hours. In the naïve control group the incidence of grade 1 responses was 3 of 10 at 24 hours and 2 of 10 at 48 hours. The mean severity of response to the challenge exposure were essentially equivalent between the induced group and control group of 0.6 and 0.7 at 24h, respectively; and 0.5 and 0.6 at 48h, respectively. No animals in the treated group had a severity of response that exceeded the severity of response in the control animals; "1" was the highest recorded reaction in any of the experimental animals. Note that doses in the pilot study below 5% w/v resulted in equivalent responses whereas doses above 5% w/v (10% w/v to undiluted) were reported to have more severe responses. Based on equivalent responses observed between control and test animals, the test material is not a skin sensitiser.

 

In a second study (Chevron,1995f), a Magnusson-Kligman skin sensitization maximization test was carried out on 30 female albino guinea pigs (20 test and 10 control) exposed to 1-dodecene dimer. The following concentrations of test material and vehicle were used at each stage of induction and at each stage of challenge: Intradermal induction - 25% w/v test material in dried arachis oil BP; Topical induction - 100% test material (undiluted liquid as supplied); Topical challenge- 75% w/v test material in dried arachis oil BP and 100% test material (undiluted liquid as supplied). On challenge, no skin reactions were noted at the application site in test group animals or in the control group at the 24 and 48 observations at either of the two concentrations. The test material produced a 0% sensitization rate in test (0/20) and control (0/10) animals. Hence, 1-dodecene dimer, hydrogenated is not a skin sensitizer in the Magnusson & Kligman guinea pig maximization test.

In a third study, a Buehler sensitisation test (Chevron, 1994c) was performed for 1-dodecene dimer, hydrogenated. Following a pilot study to determine the appropriate concentrations of test material to use in the induction and challenge phases, male and female guinea pigs were dermally treated with undiluted test material once /week for 6 hours for three consecutive weeks.  Following a 2 week rest period, the test animals and a naïve control group were dermally challenged with undiluted test substance. The animals were scored for skin sensitising reactions at 24 and 48 hours following the challenge phase. A grade 1 response generally indicates sensitization, provided grades of less than 1 are seen in the respective control animals.  The incidence of grade 1 responses in the test group was 3 of 19 at 24h and 7 out of 19 at 48 hours. In the naïve control group the incidence of grade 1 responses was 1 of 10 at 24 hours and 3 of 10 at 48 hours. The mean severity of response at to the challenge exposure were essentially equivalent between the induced group and control group of 0.6 and 0.5 at 24h, respectively; and 0.7 and 0.7 at 48h, respectively. No animals in the treated group had a severity of response that exceeded the severity of response in the control animals; "1" was the highest recorded reaction in any of the experimental animals. Note that all doses in the pilot study resulted in equivalent responses (i. e., the response observed at the undiluted dose was equivalent to the response at the lowest dose of 0.1% w/v in mineral oil). Based on the equivalent responses between control and test animals, it is concluded that sensitization to the test material was not induced.

Based on the above sensitsation studies for structurally analogous materials, the registered substance is not considered to be a skin sensitiser and does not meet the criteria for classification and labelling for this endpoint.

 

Read-across justification

Several criteria justify the use of the read-across approach to fill data gaps for the registered substance using 1-decene dimer, hydrogenated; and 1-dodecene dimer, hydrogenated as analogues substances. These substances are all hydrogenated poly alpha olefins, i. e., minimally branched paraffins (also known as alkanes) produced by oligomerization of 1-octene, 1-decene, and/or 1-dodecene. As described in the read-across justification appended to the CSR, these substances are similar in molecular structure, physicochemical properties, use, and manufacturing processes. Furthermore, data provided in CSR section 5.1 (IUCLID chapter 7.1) support similar toxicokinetic behavior of these minimally branched paraffins within this small carbon number range. Based on these unifying considerations, the slight difference in carbon number among these analogues is not expected to significantly impact mammalian toxicity. Therefore, it is scientifically reasonable to predict the toxicological properties for the registered substance from the properties determined for the analogues.

The nature of the read-across approach utilized here is aligned with the analogue approach as described in section R.6.2.3 of the ECHA document ‘Guidance on Information requirements and chemical safety assessment Chapter R.6: QSARS and grouping of chemicals’ (ECHA, 2008e). The similarity among molecular structure and molecular weight which provides the basis for the read-across justification is scientifically founded and therefore adequately clarifies why the properties of the registered substance may be predicted from the properties of the read-across substance(s) and more specifically, why the data submitted for 1-decene, hydrogenated (C20); and 1-dodecene dimer, hydrogenated (C24) are appropriate for the purposes of classification and labeling and/or risk assessment of the registered substance which contains similar molecules with carbon numbers in the ranges of 18 – 24 carbon atoms (at least 85% C20 and C22). 

A legislative goal of the REACH Regulation is to avoid unnecessary animal testing through promotion of replacement, reduction, or refinement of testing on vertebrate animals. Article 13 of the REACH regulation (EC) 1907/2006 states ”Information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI are met. In particular for human toxicity, information shall be generated whenever possible by means other than vertebrate animal tests, through the use of alternative methods”. The use of read-across data is one mechanism identified in Annex XI as an appropriate alternative method for fulfilling information requirements. It is the Registrants scientific opinion that the available read-across information demonstrating that saturated aliphatic hydrocarbons ranging in carbon numbers from C20 to C24 have a low potential for toxicity for this endpoint is ample evidence to support a rational judgment regarding hazard identification, classification and labeling and risk assessment for the registered substance (with a carbon number range of C18-C24). It is the Registrants scientific opinion that no new information will be gained through additional testing in vertebrate animals.

Migrated from Short description of key information:
Skin Sensitization, 3 key studies – Negative for guinea pigs (OECD TG 406), read across from 1-decene dimer, hydrogenated and 1-dodecene dimer, hydrogenated

Respiratory sensitisation

Endpoint conclusion

Additional information:

No studies were found which have evaluated the respiratory sensitization potential of the registered substance in humans or laboratory animals.

Migrated from Short description of key information:
There are no specific studies available.

Justification for classification or non-classification

Three read-across in vivo dermal sensitisation studies (according or similar to OECD 406) using established, reliable, sensitive methods in guinea pigs indicate a low skin sensitising potential for the substances tested. Therefore, the registered substance is not considered to be a dermal sensitizer; and classification and labelling as a skin irritant under EU Dangerous Substances Directive 67/548/EEC or CLP EU Regulation 1272/2008 is not warranted.

 

The registered substance is not expected to be a respiratory sensitizer.