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The effects of triclosan on puberty and thyroid hormones in male Wistar rats.

Department of Molecular Biomedical Sciences, North Carolina State University, College of Veterinary Medicine, Raleigh, North Carolina 27606, USA.
Toxicological Sciences (Impact Factor: 4.48). 11/2008; 107(1):56-64. DOI: 10.1093/toxsci/kfn225
Source: PubMed

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.

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    • "29 h ( SCCP , 2009 ) . Serial measurements of TCS in morning urine have shown relatively high consistency over time ( ICC = 0 . 56 ; ( Lassen et al . , 2013 ) ) . TCS has been shown in animal studies to cause endocrine effects , especially on the levels of thyroid hormones ( Crofton et al . , 2007 ; Dann and Hontela , 2011 ; Kumar et al . , 2009 ; Zorrilla et al . , 2009 ) . The Scientific Committee on Consumer Prod - ucts ( SCCP ) has concluded that the current maximum concentration of 0 . 3% is not safe when the aggregate exposure from all cosmetic products is considered . However , the maximum concentration is considered safe for individual products such as toothpastes , soaps and deodorants , but no"
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    • "laevis) tadpoles exposed to 0.8–12.5 ␮g/L TCS showed increased TRˇmRNA levels in the tail fin by 21 days of exposure and the promotion of growth concomitant with increased size and hypertrophy of the thyroid gland by 32 days (Fort et al., 2010, 2011; Helbing et al., 2011a,b). Collectively these studies establish a scientific foundation whereby TCS is observed to affect a critical stage of amphibian development and, with additional evidence garnered on the biological effects of TCS on the thyroid axis in mammals (Paul et al., 2010a,b; Zorrilla et al., 2009), suggest that the increased use of this broad spectrum bactericide and its prevalence as a pollutant in waterways and soils is of concern with respect to normal development of a wide range of non-target vertebrates. "
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    • "Increased expression of Cyp2b1/2 and Cyp3a1 is consistent with our previous observations from a short-term exposure, which demonstrated that a 4-day TCS exposure resulted in up-regulated expression of both Cyp2b1/2 and Cyp3a1/23 (Paul et al., 2010b). In addition, PROD activity, a marker of Cyp2b activity in the rat, was increased 2–3 fold-control for PND22 dams and PND4 neonates, consistent with previous reports (Paul et al., 2010b; Zorrilla et al., 2009). The lack of effect on PROD activity for GD20 dams was unexpected and may be due to a combination of the mild hypothyroxinemia and their unique metabolic status during pregnancy; several CYPs including Cyp2b2 protein are known to be decreased in rat liver during pregnancy and return to pre-pregnancy levels during lactation (He et al., 2005a,b). "
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