An antibacterial agent once common in soaps and toothpaste, with thyroid-related concerns and little benefit over plain soap.
Triclosan is an antibacterial and antifungal agent that was added to a wide range of "antibacterial" consumer products. Its story is a useful one, because it shows that a chemical can be widely used for years and then quietly removed once the benefit turns out to be small and the concerns real.
Historically, triclosan appeared in antibacterial hand soaps, some toothpastes, body washes, deodorants and even some kitchenware and textiles marketed as antibacterial. It is far less common than it used to be, because regulators and manufacturers have pulled it from many products, but it is still worth knowing the label cue: the word "antibacterial".
Animal studies have linked triclosan to effects on thyroid hormones and it shows endocrine activity in the lab, which is why bodies such as the US NIEHS flagged it. Just as importantly, the US Food and Drug Administration concluded that antibacterial hand soaps containing triclosan were no better than plain soap and water at preventing illness, and banned it from consumer hand soaps in 2016. So here the benefit was minimal and the swap costs you nothing.
That single habit removes essentially all everyday triclosan exposure. If you have older antibacterial products in the cupboard, there is no need to panic, but you need not replace them with more of the same.
This is one of the easiest items on the whole audit: there is no downside to choosing plain soap, so it is a clean swap with nothing lost. Good hand hygiene still matters; it just does not need an antibacterial additive to work.
Sources: US Food and Drug Administration (2016 ruling on antibacterial soaps), US NIEHS. Written by M. Videika, The Hormone Blueprint. Educational only, not a substitute for medical advice.