Until the FDA approves some of the new alternatives for meds, animal testing is the only allowed way to "prove" safety. Quotes exist because animal models are NOT perfect! As far as a source base, I don't know of any "balanced" that discuss pro and con from an "objective" point of view. You might want to google it and wade through the rhetoric.

Disclaimer: I work in pharma, don't approve of testing for cosmetics, and would very much like an alternative to animal testing for human drugs.