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

Endpoint summary

Description of key information

Skin Irritation, 3 key studies- non-irritating for rabbits (equivalent or similar to OECD TG 404) read-across 1-decene dimer, hydrogenated and 1-decene dimer with 1-dodecene, hydrogenated; 1-dodecene dimer, hydrogenated.
Eye Irritation, 3 key studies- non-irritating for rabbits (equivalent or similar to OECD 405)  read-across 1-decene dimer, hydrogenated and 1-decene dimer with 1-dodecene, hydrogenated; 1-dodecene dimer, hydrogenated.     

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

Skin Irritation

No skin irritation data were found for the registered substance. However, three key studies were identified for analogous substances; 1-decene dimer, hydrogenated; 1-decene dimer with dodecene, hydrogenated; and 1-dodecene dimer, hydrogenated. However, only one of the three studies strictly adhered to the current OECD 404 guidelines (4 hour exposure, semi-occlusive conditions) with mean scores for erythema and edema averaged over 24, 48, and 72 hours. This study was conducted with 1-dodecene dimer, hydrogenated. The remaining other two studies using occlusive methods, although considered less reliable since the exposure conditions were more stringent than the guideline, produced similar results to the semi-occluded study conducted for 4 hours. The results indicated negligible dermal irritation and classification is not warranted.

In the first study (ExxonMobil, 1994a), six New Zealand White Rabbits where exposed to 0.5ml of undiluted 1-decene dimer, hydrogenated under occluded exposure conditions for four hours. The mean erythema and edema scores were 0. The test material was determined to be both noncorrosive and nonirritating.

In the second study (Chevron, 1989c), 1-decene dimer with dodecene, hydrogenated was administered via occlusive dermal patch for four hours to six female rabbits. Each animal received treatment on three areas on the back. Dermal responses were evaluated at 1, 24, 48, and 72h post-dosing and on Days 7 and 14 according to the Draize method of scoring. Slight to well-defined erythema without edema was observed at 1 through 72 hours after patch removal and cleared by Day 7. Flaky skin was seen at 48 hours through Day 7 and disappeared by Day 14. The mean erythema and edema scores for the test material were 0.6 and 0, respectively. 

In the third study (Chevron, 1995d), 1-dodecene dimer was administered via a semi-occlusive patch for 4 hours to the shaved backs of six rabbits (4 females and 2 males) according to OECD 404 test guideline. Dermal responses were evaluated at 30 minutes, 24, 48 and 72 -hours post dosing according to the Draize method of scoring. Very slight erythema was noted at four treated skin sites 30 minutes after patch removal and persisted at two treated skin sites at the 24 hour observation. Very slight erythema was also noted at the control site of two animals at the 30 minute observation and persisted at one control site at the 24 hour observation. All treated skin sites appeared normal at the 48 hour observation. The mean erythema and edema scores for the test material were 0.1 and 0.0, respectively.

 

The potential for skin irritation following acute and repeated exposure of the analogous substance 1-decene dimer, hydrogenated was assessed in a 21-day cumulative irritation study in human volunteers (Anon, 1992). In this study, the test material was applied daily (0.2 ml under occlusive patch) for 21 consecutive days. Each patch was held in contact with the skin for 23.5 hours, then removed. Each site was given a dermal irritation score, and then fresh test material was applied. Each site was graded for skin irritation using a scale from 0 (no response visible) to 5 (intense vesibular/bullous eruption). Accordingly, there were 21 daily scores for each of the 23 individuals tested. Slight dermal irritation was observed with average scores of 1 (mild response, slight erythema and/or dryness and/or few tiny denudations or other mild responses) being achieved within 5 days of test initiation. The highest average score, approximately 1.2, was achieved on day 7, and, from that point on, scores of 1 or less were reported. The authors judged this result to be a demonstration of "negligible irritation under an occlusive patch". The positive control used in this test (0.1% sodium lauryl sulfate in water) produced average scores of 3, and the negative control, petrolatum, was not irritating.

Based on the above dermal irritation studies, the registered substance is not considered to be a skin irritant and does not meet the criteria for classification and labelling for this endpoint.

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

Eye Irritation

No eye irritation data were found for the registered substance. However, three key studies were identified for analogous substances; 1-decene dimer, hydrogenated; 1-decene dimer with dodecene, hydrogenated; and 1-dodecene dimer, hydrogenated. All three studies were performed by test methods similar or equivalent to OECD test guideline 405. The results indicated the potential for mild irritation, however classification is not warranted.

In the first study (ExxonMobil, 1990b), 1-decene dimer, hydrogenated was administered to the left eye of three male and three female rabbits to assess for ocular irritation. Ocular examinations occurred at 1h, 24h, 48h, 72h post-dosing. Ocular damage was assessed and scored according to the Draize eye test. The mean corneal opacity, iritis, conjunctivae redness, and chemosis scores following grading at 24, 48, and 72h for four out of six animals were 0, 0, 1, and 1, respectively. The mean corneal opacity, iritis, conjunctivae redness, and chemosis scores following grading at 24, 48, and 72h for the remaining two animals were 0, 0, 0.6 and 1; and 0, 0, 1.2, and 1, respectively. The test material is not considered an irritant based on these results.

In the second study (Chevron, 1989d), nine adult rabbits were treated with 1-decene dimer with dodecene, hydrogenated by instillation into the conjunctival sac of one eye.  The eyes of three rabbits were washed with distilled water for one minute after a 30 second exposure. The eyes of the other six rabbits remained unwashed. Moderate to severe conjunctival redness (Draize scores of 2 or 3) was observed in the unwashed eyes 1 hour after treatment. Corneal opacity and iridal irritation were not observed.  Irritation decreased through 24 hours, and by 48 hours all eyes were normal.  Moderate conjunctival redness (Draize scores of 2 or 3) was observed in the washed eyes 1 hour after treatment with full reversibility by 48 hours. The mean corneal opacity, iritis, conjunctivae redness, and chemosis scores following grading at 24, 48, and 72h for four out of six animals in unwashed eyes were 0, 0, 0, and 0 respectively. The remaining two animals had mean corneal opacity, iritis, conjunctivae redness, and chemosis scores following grading at 24, 48, and 72h of 0, 0, 0, and 0.33 respectively. The test material is not considered an irritant based on these results.

In the third study (Chevron, 1995), 1 -dodecene dimer, hydrogenated was administered undiluted (0.1 ml) to the right eyes of nine rabbits (6 male and 3 females) to assess for ocular irritation. In 6 animals, the material was left unwashed in the eye while in the remaining 3 animals, the material was gently washed from the eye after 30 seconds contact time using lukewarm tap water. Ocular examinations were carried out at 1h, 24h, 48h and 72 h post instillation. Ocular damage was assessed and scored according to the Draize scale for the eye. There was no corneal or iridal effects noted throughout the study. The only effect observed was conjunctivae redness in 3 of the six treated animals (unwashed) at 1 hour. The conjunctivae redness subsided by 24 hr in these animals. The mean corneal opacity, iritis, conjunctivae redness, and chemosis scores following grading at 24, 48, and 72h for all six animals with or without irrigation were 0, 0, 0, and 0, respectively. The test material is not considered an irritant based on these results

Based on the above eye irritation studies, the registered substance is not considered to be an eye irritant and does not meet the criteria for classification and labelling for this endpoint.

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

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; 1-decene dimer with dodecene, 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); 1-decene dimer with dodecene, hydrogenated (C20-C24); 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.

Effect level: empty Endpoint conclusion: Adverse effect observed

Justification for classification or non-classification

The registered substance does not meet the criteria for classification and labelling as a skin irritant under EU Dangerous Substances Directive 67/548/EEC or CLP EU Regulation 1272/2008 based on evaluation of the overall mean erythema and oedema scores from skin irritation studies with structural analogues.

 

The registered substance does not meet the criteria for classification and labelling as an eye irritant as defined by EU Dangerous Substances Directive 67/548/EEC or CLP EU Regulation 1272/2008 based on read-across studies to structural analogues which were not irritating to the eyes of rabbits.