Environmentally relevant concentrations of triclosan induce lethality and disrupt thyroid hormone activity in zebrafish (Danio rerio).

Triclosan is an antimicrobial agent that has been used in common household products and can be detected in water environment. In this study, therefore, I aimed at clarifying the effects of environmentally relevant concentrations of triclosan on the early life stage development in zebrafish. A lethal effect was observed: the lowest effect and the no effect concentrations were 70.6 and 48.4 μg/L, respectively. These concentrations are very close to the environmentally detected residual concentrations. In 10.9, 19.8, 48.4, and 70.6 μg/L of triclosan, the iodothyronine deiodinase 1 gene expression was found to be significantly increased when compared with that of the control group. These findings indicate that triclosan can potentially disrupt the thyroid hormone activity in zebrafish. The exposure to triclosan (at 149.2 μg/L) was also found to inhibit the gene expression of insulin-like growth factor-1. My findings suggest that triclosan can exert a thyroid hormone-disrupting effect on fish.