After the discovery of the formation of acrylamide during heat processing of the food, more recent studies have also indicated that the simple organic molecule furan is present in a wide variety of foods and may also be formed during heat processing. Like acrylamide, furan until recently has also been known only as an industrial chemical and most of the toxicity data elaborated up to now are not a suitable basis for a the required detailed risk assessment of human exposures to furan with food.
Since the mechanisms of carcinogenic activity of furan in rodents are not well understood, the objectives of this proposal are to generate relevant mechanistic information as a support for the ongoing risk assessment of human furan exposures with food. The importance of mode-of-action research on furan is underscored by the comparatively small difference in the estimated human exposures and the doses of furan, which cause carcinoma in the liver of experimental animals.
A detailed elucidation of genotoxic and non-genotoxic mechanisms and their possible dose-response relationships and interconnectivity are of fundamental importance for a reliable risk assessment.
The final outcome of the proposed research will be a careful assessment of the genotoxic potential of furan in the target cells in vivo for carcinogenicity, generation of information on the potential relevance of DNA lesions and the tissue environment changes that may exacerbate mutations. The methods applied will include state-of-the-art analytical procedures to quantify furan induced DNA-adducts in very low concentrations and other DNA-damage or cytogenetic changes, biomarkers, gene-arrays and modern cell biology to characterize furan induced changes in cellular function in the target cells of carcinogenesis in relevant species.
The proposed research has the following major objectives:
- Characterization and quantitation of DNA- and protein binding of furan in liver of rats and mice over a wide dose range. Both responses after single and after repeated exposures will be assessed. (WPs 1.1 and 1.2)
- Analysis of biomarkers of toxicity, genotoxicity and epigenetic changes affecting gene expression, tissue structure changes and cell proliferation in target cell populations of furan in order to elucidate cell-specific mechanisms. Again, special attention will be given to determine the dose dependence of the effects. (WPs 2.1. and 2.2)
- Assessment of the genotoxic and clastogenic potential of furan in rodent liver by comet assay, cytogenetics and biomarkers of genetic damage. (WPs 3.1 and 3.2)
- Assessment of the role of the accumulation of oxidative DNA damage in the mechanism of neoplastic transformation by means of a genetically modified mouse models. (WP 4)
- Detailed analysis of gene expression changes. (WP5)
- Characterization and quantitative assessment of genetic changes induced by furan and cis-2-butene-1,4-dial in mammalian cells with special consideration on mechanisms for induction of gene mutations and cytogenetic changes. (WPs 6.1, 6.2 and 6.3)
- Characterization of furan and cis-2-butene-1,4-dial induced effects on toxicity parameters, and DNA-damage in cell culture models for the specific target cells of furan in order to elucidate cell-specific mechanisms. (WP 7)
- Analysis of furan in food as a better basis for exposure assessment from food and mechanisms of formation during food processing. (WPs 8.1 and 8.2)
- Provision of a risk assessment of furan in food. (WP 9)
The results will provide data on the mode-of-action of furan induced liver carcinogenesis as a basis for a conclusive assessment of health risks in humans due to dietary exposure. Combining these findings will provide a risk/benefit analysis and a scientific basis to justify limits for human furan exposures. All results of the project will be published in peer-reviewed scientific journals to make the scientific and regulatory community aware of the project results and as a measure of project success. Assessment and evaluation of WP results and progress towards the objectives will be monitored by the participants in each workpackage.