RESEARCH ARTICLE Functional and proliferative effects of repeated low-dose oral administration of furan in rat liver Angela Mally 1 , Carmen Graff 1 , Olga Schmal 1 , Sabrina Moro 1 , Carolin Hamberger 1 , Ute M. Schauer 1 , Jens Br . uck 2 , Sibel O ¨ zden 1à , Max Sieber 1 , Ulrich Steger 3 , Dieter Schrenk 2 , Gordon C. Hard 4 , James Kevin Chipman 5 and Wolfgang Dekant 1 1 Department of Toxicology, University of W . urzburg, Germany 2 University of Kaiserslautern, Kaiserslautern, Germany 3 Department of Surgery, University of W . urzburg, W . urzburg, Germany 4 Private Consultant, Tairua, New Zealand 5 School of Biosciences, The University of Birmingham, Birmingham, UK Received: February 3, 2010 Revised: March 19, 2010 Accepted: March 25, 2010 Scope: Furan, a food contaminant formed during heat processing, induces hepatocellular tumors in rodents and high incidences of cholangiocarcinomas in rats even at the lowest dose (2 mg/kg b.w.) administered. Initial estimates suggested that human intake of furan may be as high as 3.5 mg/kg b.w./day, indicating a relatively narrow margin of exposure. The aim of this study was to establish dose–response data for cytotoxicity, regenerative cell proliferation and secondary oxidative DNA damage in livers of male F344 rats treated with furan at doses r2 mg/kg b.w. for 28 days. Methods and results: No significant signs of hepatotoxicity other than a mild, dose-dependent increase in serum cholesterol and unconjugated bile acids, and no evidence of oxidative DNA damage were seen. Histopathological alterations and proliferative changes were restricted to subcapsular areas of the left and caudate liver lobes. Conclusion: Although statistically significant effects were only seen at the 2 mg/kg b.w. dose during the course of our study, a two and threefold increase in 5-bromo-2 0 -deoxyuridine labeling index was observed at 0.1 and 0.5 mg/kg b.w., respectively, suggesting that chronic exposure to doses even below 2 mg/kg b.w. may cause proliferative changes in rat liver and highlighting the need to assess furan carcinogenicity at lower doses. Keywords: Carcinogenicity / Cell proliferation / Furan / liver 1 Introduction In 2004, a survey by the US Food and Drug Administration (FDA) revealed the presence of the chemical furan in a variety of foods that undergo heat treatment, such as coffee, canned and jarred foods including baby food, http:// www.cfsan.fda.gov/dms/furandat.html. Furan, which is widely used as an industrial chemical, is a potent hepato- toxicant and liver carcinogen in rodents. In a 2-year bioassay conducted by the National Toxicology Program (NTP), furan was reported to cause a significant increase in hepatocellular adenomas and carcinomas in male and female B6C3F1 mice and male Fischer 344 rats and high incidences of cholan- giocarcinomas in rats of both sexes (Table 1) [1]. Impor- tantly, tumor induction with high incidences was shown to occur even at the lowest doses administered (2 and 8 mg/kg b.w. in rats and mice, respectively) [1]. Abbreviations: 8-oxo-dG, 8-oxo-7,8-dihydro-2 0 -deoxyguanosine; BrdU, 5-bromo-2 0 -deoxyuridine; CK, creatinine kinase; H&E, hematoxylin and eosin; OPLS-DA, orthogonal projection to latent structure-discriminant analysis; PCA, principle component anaylsis à Current address: Department of Pharmaceutical Toxicology, Faculty of Pharmacy, Istanbul University, Istanbul, Turkey Correspondence: Dr. Angela Mally, Department of Toxicology, University of W . urzburg Versbacher Str. 9, 97078 W . urzburg, Germany E-mail: mally@toxi.uni-wuerzburg.de Fax: 149-931-20148865 & 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.mnf-journal.com 1556 Mol. Nutr. Food Res. 2010, 54, 1556–1567 DOI 10.1002/mnfr.201000064