Octadecene, reaction products with hexadecene, hydrogenated

Carcinogenicity

Description of key information

This review was undertaken to assess the carcinogenic potential of SynNova® Base Oil (CAS: 2241366-04-9). The focus of the review was on tests and studies that included genotoxicity endpoints and a 90-day oral (gavage) toxicity study in rats. The assessment looked for the principal factors in carcinogenesis that have been identified by many authors including genotoxicity, hormonal modulation, immunosuppression, chronic toxicity and changes in cell growth or survival (hyperplasia, hypertrophy, or apoptosis). All reports reviewed were GLP-compliant and were considered to be valid.

Genotoxicity was comprehensively characterised in three tests in vitro and in one test in vivo. The overall conclusion from these studies is that SynNova® Base Oil does not have any genotoxicity either in vitro or in vivo While there was no toxicokinetic evidence in the in vivo test that the exposure of the bone marrow was achieved, this is considered to be offset by the absence of effect in vitro, where the test systems were directly exposed to the test item.

Hormonal modulation was examined in three studies in rats, including a definitive study conducted according to OECD test guideline 443. There was no evidence of any effect on hormonal function, seen as a lack of treatment-related change in thyroid hormone concentrations, in thyroid weight and morphology and in similar absence of change in other endocrine tissues, including the adrenals, pituitary and gonads.

There was no indication of immunological change in any of these studies shown by the absence of change in the thymus  or in other immune system tissues. In particular, there were no differences in white cell counts (total or differential) or in protein fractions (total protein, albumin, globulins or AG ratio) to indicate any immunological effect.

There was no toxicity in any of these studies in rats that might be seen as pro-carcinogenic. In particular, there was no evidence of hypertrophic or focal change, particularly in the liver, that might indicate effects on cell turnover – either increased or decreased – that might be associated with carcinogenic potential.

The potential utility of further testing for carcinogenicity was considered and given the universally negative results in the studies reviewed and the doubtful utility of such studies in human risk assessment, it was concluded that such studies would not add materially to the information already available on SynNova® Base Oil.

The conclusion of this review of a number of GLP-compliant studies of genotoxicity, both in vitro and in vivo, and of three comprehensive studies in rats was that SynNova® Base Oil does not exhibit any carcinogenic potential and that further testing would not add usefully to the information already available.