Though I don't know if chemicals are bad for you, I like to think that anytime you apply an unnatural chemical to your skin, it can't be a good thing. Granted, that isn't as bad as the harmful effects of the sun, with over 1 million skin cancer cases diagnosed annually.
I use minimal sun block, but wear clothing which blocks out the harmful UV rays. Most notably I wear, Omni-shade products from Columbia Sportswear and Sun Guard garments from Ex Officio. I don't have to reapply sunscreen, and it keeps me sunburn free.