ToxSci Advance Access originally published online on October 21, 2008
Toxicological Sciences 2009 107(1):56-64; doi:10.1093/toxsci/kfn225
Published by Oxford University Press 2008.
Leah M. Zorrilla*,‚Ä†,
Emily K. Gibson‚Ä†,
Susan C. Jeffay‚Ä†,
Kevin M. Crofton‚Ä°,
Woodrow R. Setzer¬ß,
Ralph L. Cooper‚Ä† and
Tammy E. Stoker‚Ä†,1
* Department of Molecular Biomedical Sciences, North Carolina State University, College of Veterinary Medicine, Raleigh, North Carolina 27606
‚Ä† Reproductive Toxicology Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development
‚Ä° Neurotoxicology Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development
¬ß National Center for Computational Toxicology, United States Environmental Protection Agency, Research Triangle Park, North Carolina 27711
1 To whom correspondence should be addressed at MD-72, Endocrinology Branch, Reproductive Toxicology Division, NHEERL, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711. Fax: (919) 541-5138.
Received August 27, 2008; accepted October 15, 2008
Triclosan (5-chloro-2-(2,4-dichlorophenoxy)phenol) is a potent antibacterial and antifungal compound that is widely used impersonal care products, plastics, and fabrics. Recently triclosan has been shown to alter endocrine function in a variety of species. The purpose of this study was to determine effects of triclosan on pubertal development and thyroid hormone concentrations in the male rat. Weanling rats were exposed to 0, 3, 30, 100, 200, or 300 mg/kg of triclosan by oral gavage from postnatal day (PND) 23 to 53. Preputial separation (PPS) was examined beginning on PND 33. Rats were killed on PND 53, organ weights were recorded and serum was collected for subsequent analysis. Triclosan did not affect growth or the onset of PPS. Serum testosterone was significantly decreased at 200 mg/kg, however no effects were observed on androgen-dependent reproductive tissue weights. Triclosan significantly decreased total serum thyroxine (T4) in a dose-dependent manner at 30 mg/kg and higher (no observed effect level of 3 mg/kg). Triiodothyronine (T3) was significantly decreased only at 200 mg/kg, but thyroid stimulating hormone was not statistically different at any dose. Liver weights were significantly increased at 100 mg/kg triclosan and above suggesting that the induction of hepatic enzymes may have contributed to the altered T4 and T3 concentrations, but it does not appear to correlate with the T4 dose-response. This study demonstrates that triclosan exposure does not alter androgen-dependent tissue weights or onset of PPS; however, triclosan exposure significantly impacts thyroid hormone concentrations in the male juvenile rat.
Key Words: triclosan; puberty; thyroid hormone.
Disclaimer: The research described in this article has been reviewed by the National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency and approved for publication. Approval does not signify that the contents necessarily reflect the views and policies of the Agency, nor does mention of trade names or commercial products constitute endorsement or recommendation for use.
Online ISSN 1096-0929 – Print ISSN 1096-6080
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