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Key value for chemical safety assessment

Additional information

There are no specific mutagenicity data for the intermediate however; there are substantial data on the mutagenicity of specific components present. Of these, 1,3-butadiene has been shown to be mutagenic.


n-Hexane in not considered by the ASTDR (1999) to be mutagenic in in vitro or in vivo tests.


Cyclohexane has been examined for mutagenicity both in vitro and in vivo in a range of recognised core assay types. The key in vitro studies are considered to be a bacterial mutation assay (Mortelmans et al, 1986) and a mammalian cell mutation assay (Litton Bionetics, 1982; HLA, 1982h). It was not mutagenic in either test system. There are additional reports of Salmonella and mouse lymphoma mutation data that support these data and there are also reports of the following further assay types on cyclohexane: sister chromatid exchange in mouse lymphoma cells, unscheduled DNA synthesis in human lymphocytes, a DNA cell binding assay in E coli. The data from these assays all support the above conclusion that cyclohexane is not mutagenic in vitro (EU RAR, 2004). The key in vivo study is a cytogenetic study in the rat (Litton Bionetics, 1982). Cyclohexane was not mutagenic in this assay. The available data indicates that cyclohexane has no significant genotoxicity.


4-vinylcyclohexene was tested by the NTP (1989 and 1981) in bacterial mutation assays and was found to be non-mutagenic in the presence and absence of rat or hamster S9. 4-vinylcyclohexene did not produce any statistically significant increases in sister chromatid exchanges in CHO cells with or without activation at any of the concentrations tested, nor was there a positive dose-related trend, nor did it produce any statistically significant increases in total aberrations, complex aberrations, simple aberrations, or other aberrations in CHO cells with or without activation at any concentration tested (NTP, 1984). 4-vinylcyclohexene was reported to be mutagenic in mouse lymphoma cells in the presence of S9 metabolic activation (NTP, 1981). There are 2 in vivo studies, both micronucleus studies in the rat and mouse; 4-vinylcyclohexene did not cause any apparent physiological or toxic effects on the bone marrow or induce chromosomal or spindle damage in the nucleated erythroblast cells. While results from in vitro genetic toxicology tests are mixed, although predominantly negative, the in vivo data reinforce that 4-vinylcyclohexene has no significant genotoxicity.



Toluene was negative in two bacterial mutation assays (Bos et al, 1981; Haworth et al, 1983) both with and without S9. API (1978) examined toluene in the L5178Y (TK+/-) mouse lymphoma assay and was negative. There are a number of additional reports of toluene being found negative using in vitro assays including endpoints of gene mutation and DNA repair in bacteria, gene conversion in yeast (EU RAR, 2003), and in mammalian cells with endpoints of DNA strand breaks, DNA damage/repair, sister chromatid exchange and micronucleus induction (EU RAR, 2003). The data from these assays all support the above conclusion that toluene is not mutagenic in vitro. In vivo, toluene was negative in a cytogenetic study in the rat (API, 1978). A number of additional cytogenetic studies have been carried out in the rat and mouse, and their findings support the conclusion that toluene is non-genotoxic in somatic cells in vivo (EU RAR, 2003). In addition, toluene has been examined for genotoxicity in germ cells. API (1981) evaluated toluene in the dominant lethal assay in male CD-1 mice. Toluene was considered not to be mutagenic as it did not increase pre- or post implantation embryo loss. In humans a number of studies have examined occupational settings where toluene has been in use, and reported changes in certain genotoxicity parameters. However, equivocal results have been obtained and the inability to control confounding factors such as possible co-exposure to other agents does not allow meaningful conclusions for toluene (EU RAR, 2003). Prolonged exposure to 50 ppm toluene did not induce increased frequencies of sister chromatid exchange in peripheral blood lymphocytes of human volunteers (EU RAR, 2003).

It is concluded that the available data indicate that toluene has no significant genotoxicity.



Minor components with classification for genotoxicity


1,3-butadiene, has been identified as present and shown to be mutagenic in vivo.


1,3-Butadiene (Classification: EU –Toxic T Mutagen Cat 2 R46; GHS/CLP - Category 1B, H340): In non-human studies, 1,3-buta-diene is genotoxic in vitro and is genotoxic in vivo in both somatic and germ cells in the mouse (Araki et al, 1994, Asakura et al, 2008, Adler et al, 1994). The available data on several groups of 1,3-butadiene-exposed workers did not show any association between 1,3-butadiene exposure and increased gene mutations, primarily HPRT mutations. No 1,3-butadiene-related chromosome aberrations have been demonstrated in humans (Albertini et al 2001, 2003, 2007).

Complex substances and intermediates are considered to be mutagenic if they contain ≥0.1% 1,3-butadiene.



Additional References


ATSDR (1999). Toxicological Profile for n-Hexane.U.S. Department of Health and Human Services Public Health Service Agency for Toxic Substances and Disease Registry. html

EU RAR (2003). European Union Risk Assessment Report for Toluene. EC Joint Research Centre http: //ecb. jrc. ec. europa. eu/DOCUMENTS/Existing- Chemicals/RISK_ASSESSMENT/REPORT/toluenereport032. pdf

EU RAR (2004). European Union Risk Assessment Report: Cyclohexane. EC Joint Research Centre

Short description of key information:
No data are available for the intermediate however information is available for the major and minor components. Of these, 1,3-butadiene has been shown to be mutagenic and because it is present at a concentration greater than 0.1%, mandatory classification for mutagenicity will be required.

Endpoint Conclusion: Adverse effect observed (positive)

Justification for classification or non-classification

No data are available for the intermediate; however information is available for the major and minor components which show that most have negative mutagenic potential in vitro and in vivo when tested in a range of recognised core assay types.

However, the intermediate contains the minor component 1,3-butadiene at ≥0.1% and therefore is considered to be mutagenic. A mandatory classification of “May cause heritable genetic effects” Cat 2, R46 under Dir 1999/45/EC and “May cause genetic defects” Cat 1B, H340 under Reg (EC) 1272/2008 is required.