@croydon - I know plenty of people who refuse to use antiperspirant sprays because they think it's unnatural to block the sweat coming out.
Either they think it will harm your skin, or that it can harm your body systems by blocking a natural process.
I use it myself and have not had any problems, but I can see their point. It does seem a bit dangerous to stop sweat, but generally I don't find them that strong.
If I'm working out at the gym, they don't seem to work all that well, so I guess they can't be that dangerous either.