The Effects of Triclosan on Puberty and Thyroid Hormones in Male Wistar Rats

Triclosan (5-chloro-2-(2,4-dichlorophenoxy)phenol) is a potentantibacterial and antifungal compound that is widely used inpersonal care products, plastics, and fabrics. Recently triclosanhas been shown to alter endocrine function in a variety of species.The purpose of this study was to determine effects of triclosanon pubertal development and thyroid hormone concentrations inthe 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 beginningon PND 33. Rats were killed on PND 53, organ weights were recordedand serum was collected for subsequent analysis. Triclosan didnot affect growth or the onset of PPS. Serum testosterone wassignificantly decreased at 200 mg/kg, however no effects wereobserved 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 observedeffect level of 3 mg/kg). Triiodothyronine (T3) was significantlydecreased only at 200 mg/kg, but thyroid stimulating hormonewas not statistically different at any dose. Liver weights weresignificantly increased at 100 mg/kg triclosan and above suggestingthat the induction of hepatic enzymes may have contributed tothe altered T4 and T3 concentrations, but it does not appearto correlate with the T4 dose-response. This study demonstratesthat triclosan exposure does not alter androgen-dependent tissueweights or onset of PPS; however, triclosan exposure significantlyimpacts thyroid hormone concentrations in the male juvenilerat.