The mutagenic potential of high flash aromatic naphtha

Catalytic reforming is a refining process that converts naphthenes to aromatics by dehydrogenation to make higher octane gasoline blending components. A portion of this wide boiling range hydrocarbon stream can be separated by distillation and used for other purposes. One such application is a mixture of predominantly 9-carbon aromatic molecules (C9 aromatics, primarily isomers of ethyltoluene and trimethylbenzene), which is removed and used as a solvent — high-flash aromatic naphtha. A program was initiated to assess the toxicological properties of high-flash aromatic naphtha since there may be human exposure through inhalation or external body contact. The current study was conducted partly to assess the potential for mutagenic activity and also to assist in an assessment of carcinogenic potential. The specific tests utilized included the Salmonella/mammalian microsome mutagenicity assay, the hypoxanthine-guanine phosphoribosyl transferase (HGPRT) forward mutation assay in CHO cells, in vitro chromosome aberration and sister chromatid exchange (SCE) assays in CHO cells, and an in vivo chromosome aberration assay in rat bone marrow.There was no evidence that high-flash aromatic naphtha was either a gene or chromosomal mutagen. Thus it is unlikely to be a genotoxic carcinogen.Abbreviations Brdu 5-Bromo-2-deoxyuridine - C9 Aromatic species with 9 carbons (i.e., ethyl toluene and trimethyl benzene isomers) - CE Cloning efficiency - CHO Chinese hamster embryo - CP Cyclophosphamide - DMSO Dimethyl sulfoxide - HGPRT Hypoxanthine-guanine phosphoribosyl transferase - HVAC Heating, Ventilation, Air Conditioning - 3MC 3 Methylcholanthrene - MMC Mitomycin C - MMS Methyl methanesulfonate - S9 S9 Mammalian microsomal enzyme activation mixture - SCE Sister chromatid exchange