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

Endpoint summary

Additional information

In vitro

In vitro bacterial reverse mutation assays exist for butylene dimers, trimers and tetramers; studies on other higher olefins are used to cover the carbon number range C8 to C20.  All of these butylene oligomers and higher olefins are not genotoxic.

No mutagenic activity was observed with isooctene (up to 5,000 ug/plate) when tested with S. typhimurium or E.coli strains in the presence or absence of metabolic activation (CAS 11071 -47 -9, HLS, 2009 a). 2,4,4-Trimethylpentene was not mutagenic to S. typhimirium or E. coli strains in the presence or absence of metabolic activation at concentrations up to 5,000 ug/plate (HLS, 1996 e).  Triisobutylene (CAS 7756 -94 -7) was not mutagenic to S. typhimirium or E. coli strains in the presence or absence of metabolic activation at concentrations up to 5,000 Ig/plate (Hatano Research Institute a). Tributene (CAS 97280 -83 -6) was also not mutagenic to S. typhimurium and E. coli strains in the presence or absence of metabolic activation at up to 5,000 ug/plate (HLS, 2009 b). Neither was tetrabutene (CAS 9003 -29 -6) mutagenic to S. typhimurium or E. coli strains in the presence or absence of metabolic activation at up to 5,000 ug/plate (Harlan, 2009). C2-24 alkenes, linear and branched were also found to be non-mutagenic to bacterial strains of S. typhimurium and E.coli in the presence or absence of metabolic activation at concentrations up to 5,000 ug/plate (SafePharm, 1998 c).

2,4,4-Trimethylpentene was negative when tested in an in vitro chromosomal aberration test using human peripheral blood lymphocytes in the presence or absence of metabolic activation (HLS, 1997 d). Triisobutylene was negative when tested in an in vitro chromosomal aberration test using Chinese hamster CHL/IU cells in the presence or absence of metabolic activation (Hatano Research Institute b).

 

In vivo

An in vivo cytogenetics test exists for diisobutylene (butylene dimer); other studies on other higher olefins are used to cover the carbon number range C8 to C20 for this category. All of these higher olefins including diisobutylene are not genotoxic.

Diisobutylene did not significantly increase the incidence of micronucleated polychromatic erythrocytes in male or female rats exposed by inhalation to concentrations of 0, 995, 2035 or 4015 ppm for 4 hours (WIL, 2006). A single oral dose of 7.85 g/kg hexadecene (CAS 629 -73 -2) was not genotoxic in a mouse bone marrow micronucleus assay (Research Institute for Organic Synthesis, 1990). No increased micronuclei were noted in a mouse bone marrow micronucleus assay at intraperitoneal doses of 0, 500, 1000 or 2000 mg/kg C20-24 alkenes, branched and linear (SafePharm, 1998 d). 

Short description of key information:
There is no evidence of mutagenicity in vitro or in vivo in a range of recognised core assay types conducted with butylene oligomers or representative olefins. In vitro studies comprise six bacterial reverse mutation assays with olefins ranging from C8 to C20/24 and two mammalian chromosome aberration tests with C8. There are also four negative in vivo mammalian erythrocyte micronucleus tests in the mouse or the rat covering three different routes of administration oral, inhalation and intraperitoneal and olefins ranging from C8 to C20/C24. The results are consistent throughout the category.

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

There is no evidence of mutagenicity in a range in vitro and in vivo studies with linear and branched olefins ranging from C8 to C20/C24 and there is sufficient evidence to conclude that butylene oligomers do not warrant classification under DSD Dir 67/548/EEC or GHS/CLP.