Triclosan is an antimicrobial chemical found in personal care and sanitizing products. It can be found in soaps, toothpaste, and hair products. But there have been recent concerns about its possible effects on human health -- and triclosan has been detected in human breast milk, blood, and urine samples.
A study evaluated the effects of triclosan in female rats. Triclosan was found to advance the age at which the rats hit puberty. Serum thyroid hormone concentrations were also suppressed by triclosan.
According to the study, as reported by Green Med Info:
“In conclusion, triclosan affected estrogen-mediated responses in the pubertal and weanling female rat and also suppressed thyroid hormone in both studies.”