I've been trying to find a suitable deodorant/antiperspirant. There was an old rumor that using these products may lead to breast cancer, but this urban legend was debunked. Now people are worried about antiperspirants containing aluminum, which has been linked to Alzheimer's disease, although the research has been inconclusive.
Even forgetting about these dubious scares, I'm concerned about any product that blocks my body's natural cooling mechanism. Antiperspirants work by plugging your pores so you don't sweat. Sure, I may smell better using them, but given how much I work out, my body would probably overheat. Not acceptable. Plus I have yet to find a commercial deodorant/antiperspirant that doesn't have an overpowering smell. Most fragrances, including perfumes, give me a headache.
Following the advice of a fellow group exercise instructor on Turnstep.com, I bought a Crystal Stick from Whole Foods. It's AWESOME! I can't recommend it enough. At the risk of sounding like a commercial, it's fragrance free (yay!), non-sticky, non-staining, eliminates odor, leaves no white residue and environmentally safe. According to the website, it's "made of 100% mineral salts with no artificial coloring or ingredients, chemicals or dyes". It works by killing the bacteria that causes the odor, as opposed to masking the smell. Makes sense to me!