From what I understand, tampon companies aren't strictly required to list what's in their products. I'm not sure if that's true, but it might be why it's a bit hard to find precise lists. I've tried and can't find much.

Though while researching cups, I dove into the health benefits and risks of other menstrual products, as well, so for the benefit of anyone reading this, here's what I learned:

To start, many tampons are made of rayon instead of cotton. It seems that rayon encourages bacteria growth more than cotton and many mass-produced tampons leave lots of lint behind upon removal. Basically this means that any bacteria have a ton of new spots to breed even when the tampon's gone (not sure if the good, helpful bacteria ever take advantage of this). If you're dried out by the tampon it can cause micro-tears in the vaginal wall, allowing this bacteria into the bloodstream.

The two chemicals that got plenty of mention were bleach and dioxins - neither are things you want in your vagina or anywhere else in your body (though to be fair they're found in plenty of things besides tampons). Cotton tampons don't usually seem to have these, but unless the cotton's organically grown there's probably pesticides in it. Plenty of sites and blogs also complained of ambiguous ingredient listings on tampons, such as "fragrance."

And just because I found it totally gross, here is a blog post about a tampon, fresh out of the package, that had mold on it. This is why, if I ever did need to use a tampon again (*shudder*), I won't use one with an applicator.