FDA Probes 'Hormone Disrupter' in Soap, Toothpaste Studies in animals point to risk By Emily Rauhala, Newser User Posted Apr 9, 2010 4:49 AM CDT 7 comments Comments Triclosan is a common ingredient in soap. (Shutter Stock) (Newser) – The Food and Drug Administration is taking a closer look at an antibacterial found in soap and toothpaste. Animal studies of the substance, triclosan, suggest it may alter hormone regulation or help develop resistance to antibiotics, Reuters notes. "There are many troubling questions about triclosan's effectiveness and potentially harmful effects, especially for children," said Massachusetts Rep. Edward Markey, who is calling for a ban on triclosan in soap. FDA officials said there's no proof yet that triclosan is harmful to humans, but officials are reviewing scientific studies.