Hydrocarbons, C4 and C8, butene concentrator by-product

Endpoint summary

Description of key information

Tetrabutene (mixture of C16 and C20 olefin isomers) was found to be non irritating to the skin.  However C8 and C12 butylene oligomers using occlusive dressings were found to be irritating to rabbit skin.  In a study where a semi occlusive dressing was used, 2,4,4, TMP (a C8 olefin) was found to be non-irritating.  However another C8 substance, diisobutylene was found to be moderately irritating to rabbit skin using semi-occlusive conditions.
In four representative studies it was found that the test materials were not irritating to the rabbit eye.
There are no specific studies on respiratory tract irritation but there was no evidence of respiratory tract irritation in a 90 day inhalation with isooctene.

Additional information

Non-human data

Skin Irritation

Isooctene (CAS 11071-47-9, 18% n-octene; and 58% methylheptene and 24% dimethylhexene isomers) was found to be irritating to the skin of rabbits when applied for 4 hours under occlusive conditions (Huels AG, 1986 d). Both the erythema and edema were not fully reversible within 14 days of application. 2,4,4 TMP (a C8 olefin) was found not to be irritating to the skin of rabbits when applied for 4 hours under semi-occlusive conditions (HLS, 1996 c). In a further study with the C8 olefin diisobutylene using semi-occlusive conditions the test material was found to be moderately irritating to rabbit skin. Tributene (CAS 39133 -31 -8, a mixture of C12 olefin isomers) was also found to be irritating to the skin of rabbits when applied for 4 hours under occlusive conditions (Huels AG, 1986 e). Tetrabutene (CAS 9003 -29 -6, 70% of a mixture of C16 olefin isomers; 30% of a mixture of C20 olefin isomers) was not irritating to the skin of rabbits when applied for 4 hours under occlusive conditions (Huels AG, 1986 f).

Eye irritation

Instillation of 0.1 ml of undiluted isooctene (CAS 11071 -47 -9, 18% n-octene; and 58% methylheptene and 24% dimethylhexene isomers) was a non-irritant to the eyes of rabbits (Huels AG, 1986 g). 2,4,4-Trimethylpentene, another C8 olefin isomer, was also found not to be irritating to eyes of rabbits (HLS, 1996 d). Instillation of 0.1 ml of undiluted tributene (CAS 39133 -31 -8, a mixture of C12 olefin isomers) was a non-irritant to the eyes of rabbits (Huels AG, 1986 h). Instillation of 0.1 ml of undiluted tetrabutene (CAS 9003 -29 -6, 70% of a mixture of C16 olefin isomers; 30% of a mixture of C20 olefin isomers) was not irritating to the eyes of rabbits (Huels AG, 1986 i).

Respiratory Tract Irritation

No studies on respiratory tract irritation have been conducted with any butylene oligomers . In the combined subchronic vapour inhalation study with reproduction/developmental toxicity screening test in Wistar rats with isooctene (CAS 11071 -47 -9, BASF, 2007) there is no evidence of respiratory irritation.

Human data

No human information is available.

Justification for classification or non-classification

C16 and C20 olefin isomers have been tested and do not warrant classification as irritating to the skin under Dir 67/548/EEC or GHS/CLP. However there are two studies which indicate a classification of Xi R38 Irritating to the skin (DSD Dir 67/548/EEC ) and Category 2 H315 Causes skin irritation (CLP Reg (EC)1272/2008) is required for C8 and C12 butylene oligomers.

Butylene oligomers do not warrant classification as irritating to the eye under Dir 67/548/EEC or GHS/CLP.

Although there are no specific acute studies of respiratory irritation, longer term non human studies do not show any evidence of respiratory irritation.