Triclosan, a chemical used in antibacterial soaps and toothpastes, has been shown to hasten the transformation of tadpoles into adult frogs.
This means that triclosan can act as an endocrine disrupter, upsetting the delicate hormone balance of animals. Triclosan has already been shown to bioaccumulate in fish and contaminate human breast milk.
The effects of triclosan on the tadpoles included significant weight loss and accelerated hind-limb development. There was also elevated activity of genes linked with uncontrolled cell growth, and decreased gene activity in the tail fin.
Triclosan alone does not cause the effect, but only triclosan in the presence of thyroid hormones. This suggests that triclosan makes thyroid hormones much more potent, and speeds up their impact.
Triclosan may be making protein receptors in the cell more sensitive to thyroid hormones.Thyroid-hormone signaling is essential for the development of the human brain and body, so these findings could have an impact on human health.