Hydrocarbons, C4 and C8, butene concentrator by-product

Endpoint summary

Description of key information

Acute toxicity studies exist for higher olefins including butylene oligomers at both ends of the carbon number ranges within this category. The results are consistent throughout the category and indicate low acute toxicity by the oral, dermal and inhalation routes of exposure.  
Butylene oligomers have low  kinematic viscosity.

Additional information

Non human data

Oral

In a limit test, there were no deaths in rats following a single oral dose of 10,000 mg/kg isooctene (CAS 11071 -47 -9, 18% n-octene, 58% methylheptene and 24% dimethylhexene isomers) (Huels AG, 1986 a). Piloerection, tremors and diuresis were observed in the treated rats one hour after dosing. There were no deaths in rats following a single oral dose of 10,000 mg/kg tributene (CAS 39133 -94 -7, a C12 olefin mixture) (Huels AG, 1986 b). No deaths were observed in rats following a single oral dose of 10,000 mg/kg tetrabutene (CAS 9003 -29 -6, 70% of a mixture of C16 olefin isomers; 30% of a mixture of C20 olefin isomers) (Huels AG, 1986 c). The acute oral rat LD50 of 2,4,4-trimethylpentene (a C8 branched olefin) was greater than 2000 mg/kg, the limit dose (HLS, 1996 a, ). No deaths were observed in this study. There was no mortality and the acute oral rat LD50 of triisobutylene was greater than 2000 mg/kg, the limit dose (CAS 7756 -94 -7, Biosafety Research Center, Japan). 

Dermal

No deaths were observed when a dose of 2000 mg/kg 2,4,4-trimethylpentene, a C8 olefin isomer, was applied to the skin of rats for 24 hours (HLS, 1996 b). The acute dermal rat LD50 is >2000 mg/kg. No deaths were observed when a dose of 2000 mg/kg of C20-24 alkenes, linear and branched was applied to the skin of rats for 24 hours (Safepharm, 1998 a). The acute LD50 is >2000 mg/kg.

Inhalation In a 4 hour acute inhalation toxicity study in rats with diisobutylene, a C8 alkene, there were no mortalities and no overt signs of toxicity. The acute LC50 of diisobutylene was greater than 4185 ppm, equivalent to 19171 mg/m3 air. Exposure of 3 rats/sex to a saturated vapor of isododecene, a C12 alkene, for 7 hours at 3.8 mg isododecene/L (calculated) to 3 rats/sex resulted in no deaths (BASF, 1989). No deaths were observed when rats were exposed to a saturated vapor of C16-18 alpha olefins for 1 or 4 hours (Ethyl Corporation, 1973).

Aspiration hazard

This is a known hazard of hydrocarbons and is based on the physical characteristics of the butylene oligomers. Dodecene branched (CAS 97280-83-6) has a kinematic viscosity of 1.66mm²/s at 20^oC. Classification is based on values at 40^oC but in the absence of any other information this is considered to be below the cut off values for DSD of 7mm²/s and for GHS/CLP of 20.5 mm²/s for hydrocarbons and therefore classification is warranted.

Human data

No human information is available.

Justification for classification or non-classification

There are sufficient data available on component substances to conclude that members of the butylenes oligomers category are of low acute toxicity by the oral and dermal routes with LD50 values exceeding the doses which would warrant classification under Dir 67/548/EEC or GHS. There is limited information about the inhalation route but available data indicates LC50 values below saturated vapour pressure.

Classification and labelling is based on the chemical class and is supported by a kinematic viscosity value of 1.66 mm2/s (static) at 20 deg C for CAS  97280-83-6 (dodecene branched). Butylene oligomers warrant classification under DSD Dir 67/548/EEC Xn R65 May cause lung damage if swallowed and GHS/CLP category 1 H304 May be fatal if swallowed and enters the airways.