So how much evil can triclosan do? Along with a similar chemical, triclocarbon, it has been identified as a fish killer based on estuary sediment samples that date back to the 1960s, according to a recent study published in the journal of Environmental Science and Technology.
Personally, I don't want to be more responsible than can be helped for further depleting marine life. But if that doesn't do it for you, you should consider that triclosan is said to bioaccumulate in humans, rendering some antibiotics ineffective. The lobby groups have also pointed to the fact that studies have linked the chemical to endocrine system disruption, cancer and increased dermal sensitization.
For those of you (like me) who hadn't heard of tricolsan until now, it is sobering to discover that it is everywhere. A 2001 study published in the American Journal of Infection Control found triclosan (or triclocarban) in 76%of liquid soaps and 29% of bar soaps on the market. The study also found that there are few documented benefits of triclosan. It is also in a lipstick by Revlon, Jason Natural Cosmetics and TotalSkinCare's makeup kit, to name but a few.
Triclosan works by targeting a biochemical pathway in the bacterium without destroying its cell wall. I have no understanding of why this is a good thing for chemists, but apparently it means that triclosan is increasingly in demand by personal care product makers. They, unsurprisingly, say evidence of risks to humans is inconclusive.
UPDATE: In April 2010, the FDA announced that it would review triclosan for safety. Although it said that it "is not known to be hazardous to humans", it noted that animal studies have shown that triclosan alters hormone regulation.