Preservative suppliers have warned about it for decades, but now doctors are getting wise to the fact that makeup can be a breeding ground for bacteria and other contaminants when it is not stored properly. What's worse, using out-of-date cosmetics can result in infection, according to dermatology experts at Baylor College of Medicine in a report in the journal Cosmetic Dermatology. Dr. Ramsey Markus, professor of dermatology and an author of the study, said that of 19 cosmetic samples t...