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

Abstract

Triclosan (5-chloro-2-(2,4-dichlorophenoxy)phenol) is a potent antibacterial and antifungal compound that is widely used in personal 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.

Triclosan impairs excitation–contraction coupling and Ca 2+ dynamics in striated muscle

“…However, TCS has been detected in raw and treated waste water, natural streams, sewage sludge, fish, and human samples of urine, plasma, and breast milk (4-9), raising concerns of its potential long-term adverse impacts on environmentally sensitive species and human health. There is emerging evidence that TCS can disrupt endocrine signaling and immune function, inhibit carboxylesterase activity, bioaccumulate in organisms, and cause bacterial resistance (10)(11)(12)(13)(14)(15).…”

4-Nonylphenol, bisphenol-A and triclosan levels in human urine of children and students in China, and the effects of drinking these bottled materials on the levels

“…Some studies suggest that the increased cancers (Keri et al, 2007), human health abnormalities (cardiovascular disease and diabetes) (Lang et al, 2008) and externalizing behaviors in 2-year-old children (especially among female children) can be associated with BPA exposure (Braun et al, 2009). Although in literature there are no clear evidence that suggests that TCS has adverse effects on humans (Dayan, 2007;Sullivan et al, 2003), the disruption of the thyroid hormone system raises concern on the potential endocrine disrupting effects of TCS and possible adverse effect on humans (Crofton et al, 2007;Zorrilla et al, 2009). …”

Iodotyrosine Deiodinase, a Novel Target of Environmental Halogenated Chemicals for Disruption of the Thyroid Hormone System in Mammals

“…Among them, triclosan, a chlorinated phenolic antibacterial agent, decreases serum T4 concentration in male juvenile rats. 30) Bithionol, closantel and rafoxanide, which are used as antiparasitics in animals, exhibit thyroid hormone-like activity in reporter gene assays using a rat pituitary cell line, MtT/E2. 31) Erythrosine B and rose bengal, which are used as food colorants, disrupt thyroid function in rodents: erythrosine B affects the pituitary-thyroid axis in rats 32) and rose bengal inhibits thyroid peroxidase in vitro.…”