Hydrocarbons, C4, 1,3-butadiene-free, polymd., dibutylene fraction

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Additional information:

Non human data

Skin sensitisation

A C8 branched olefin (2,4,4-trimethylpentene) was not a dermal sensitiser when tested in an OECD TG 406 guinea pig maximisation test (HLS, 1997 a). A test group of 20 guinea pigs received 50% 2,4,4-trimethylpentene (in paraffin oil) and Freund’s complete adjuvant for intradermal induction, followed by topical application of undiluted 2,4,4-trimethylpentene under occlusive dressing for 48 hours. In the challenge, 0.03 ml of a 75% and 30% solution of 2,4,4-trimethylpentene (in paraffin oil) was applied to the intact skin for 24 hours under an occlusive dressing. The challenge application of 75% solution resulted in a positive response in 9 treated animals (45%) and 3 control animals (15%); the challenge application of 30% solution resulted in positive response in 3 treated animals (15%) and 1 control animal (5%).

Tetrabutene (CAS 9003 -29 -6, a C16 branched olefin) produced a positive response in a mouse local lymph node assay (Safepharm, 2008). A stimulation index of >3 was obtained with undiluted tetrabutene, whereas the stimulation was <3 with 75% and 25% tetrabutene (in 4:1 acetone/olive oil). However, in a Buehler Test conducted according to the OECD TG406 guidelines, a C16-18 branched olefin material (CAS 148617 -57 -6 and CAS 148617 -59 -8) was not a dermal sensitiser (Hill Top, 1995). A test group of 19 guinea pigs were treated topically with 0.3 ml undiluted C16-18 olefin for a 6 hour period, once a week for three applications. In the challenge phase, 0.3 ml of a 5% solution (in mineral oil) was applied to the intact skin for 6 hours under an occlusive dressing. The incidence of grade 1 responses was 12/19 (63%) in the treated compared to 4/10 (40%) in the control group. Upon rechallenge, the incidence of grade 1 responses in the treated group was 14/19 (74%) compared to 8/10 (80%) in the control group. In a full review of Local Lymph Node Assay (NIH, February 1999) a paper by Montelius et al. (1996) was cited which describes the effect the vehicle may have on the results. The vehicle used in the SafePharm 2008 study was 4:1 acetone olive oil v/v. The review describes olive oil as posing problems in the LLNA as it is reported as an allergen giving SI values of at least 16 when tested at 100% concentration and at least 2.9 when tested as acetone olive oil (4: 1). Due to the conflicting results obtained in the Beuhler test, it is believed that the result of the LLNA for tetrabutene is a false positive and that tetrabutene is not a skin sensitiser. 

A C20-24 branched and linear internal olefin was not a dermal sensitizer when tested in an OECD TG 406 guinea pig maximisation test (Safepharm, 1998 b). A test group of 20 guinea pigs received 25% C20-24 olefins (in arachis oil) and Freund’s complete adjuvant for intradermal induction, followed by topical application of undiluted C20-24 olefins under occlusive dressing for 48 hours. In the challenge, 75% and 30% solution of 75% and 50% C20-24 olefins (in arachis oil) was applied to the intact skin for 24 hours under an occlusive dressing. None of the treated animals showed any positive reactions 24 or 48 hours after the removal of the challenge patch.

Human data

There are no human data. Reference NIH 1999. The Murine Local Lymph Node Assay: A Test Method for Assessing the Allergic Contact Dermatitis Potential of Chemicals/Compounds The Results of an Independent Peer Review Evaluation Coordinated by the Interagency Coordinating Committee on the Validation of Alternative Methods (ICCVAM) and the National Toxicology Program Center for the Evaluation of Alternative Toxicological Methods (NICEATM), February 1999. NIH Publication No. 99-4494

Migrated from Short description of key information:
A weight of evidence evaluation of four sensitisation studies indicates that butylene oligomers are not-sensitising. Two guinea pig maximisation tests to OECD 406 for 2,4,4 trimethylpentene and for a C20-24 olefin, were negative for skin sensitisation. A mouse local lymph node study indicated a positive response for skin sensitisation for undiluted tetrabutene, however a guinea pig Buehler test with C16-C18 branched olefin conducted to OECD 406 indicates that the test material is not a dermal sensitiser. The LLNA result is believed to be a false positive due to the choice of vehicle.
There are no specific data on respiratory sensitisation.

Respiratory sensitisation

Endpoint conclusion

Additional information:

No data have been found concerning respiratory sensitisation and there are no indications that butylene oligomers are respiratory allergens.

Migrated from Short description of key information:
There are no specific data on respiratory sensitisation.

Justification for classification or non-classification

There are sufficient data to indicate that butylene oligomers are not skin sensitisers and no classification is warranted for this end-point under Dir 67/548/EEC or GHS/CLP.

Although there are no specific data on respiratory sensitisation, there is no evidence that classification is warranted for this end-point under Dir 67/548/EEC or GHS/CLP.