Toxicology 206 (2005) 359–371 Lifelong exposure to di-(2-ethylhexyl)-phthalate induces tumors in liver and testes of Sprague–Dawley rats Cristina Voss a , Heide Zerban b , Peter Bannasch b , Martin R. Berger a,∗ a Unit of Toxicology and Chemotherapy, Deutsches Krebsforschungszentrum Heidelberg, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany b Division of Cell Pathology, Deutsches Krebsforschungszentrum Heidelberg, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany Received 24 June 2004; received in revised form 21 July 2004; accepted 21 July 2004 Available online 11 September 2004 Abstract The plasticizer di-(2-ethylhexyl)-phthalate (DEHP) is the most important phthalate with respect to its production, use and occurrence in the environment. In standard carcinogenicity experiments with F344 rats and B6C3F1 mice, DEHP has been shown to induce hepatocellular tumors. Moreover, DEHP is strongly suspected to be a developmental and reproductive toxicant. The present study aimed at determining the long-term toxic effects of lifetime exposure to low concentrations of DEHP in Sprague–Dawley rat strain. Seven hundred and thirty male rats, stratified into four groups, received DEHP with the diet, resulting in dosages of 300, 95, 30 and 0 mg/kg per day for up to 159 weeks and were only sacrificed when moribund. All organs of the dead and sacrificed animals were histopathologically examined. Significantly increased tumor incidences after exposure to 300 mg/kg per day DEHP (P = 0.04 for testes and 0.05 for liver) and a significant dose-related trend (P Trend = 0.02 for testes and 0.03 for liver) were detected in both organs liver and testes. Time to tumor analysis revealed that DEHP-induced testicular tumors developed earlier in lifetime than hepatocellular neoplasias, and their multiplicity increased with time. In addition, animals exposed to the highest DEHP dose showed a significantly increased rate of testicular tubular atrophy (P < 0.01). In conclusion, this study shows for the first time that the rat testes are a target organ of DEHP carcinogenicity in Sprague–Dawley rats upon lifetime exposure. This new finding indicates the importance of evaluating the effects of lifetime exposure in assessing the potential human health risks of DEHP. In addition, the carcinogenicity should be evaluated in rat strains with low spontaneous tumor incidence in the organs known as target of DEHP toxicity. © 2004 Elsevier Ireland Ltd. All rights reserved. Keywords: Di-(2-ethylhexyl)-phthalate; DEHP; Leydig cell tumors of the testes; Epigenetic carcinogenicity; Rat liver; Lifelong exposure; Toxicity ∗ Corresponding author. Tel.: +49 6221 423310; fax: +49 6221 423313. E-mailaddresses: m.berger@dkfz.de, m.berger@dkfz-heidelberg.de (M.R. Berger). 0300-483X/$ – see front matter © 2004 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.tox.2004.07.016