The FDA doesn't approve cosmetic ingredients except color additives. Cosmetic companies can use what ever ingredients they choose with the exception of a few ingredients that are prohibited.
In 1984, the Cosmetic Ingredient Review reviewed the safety of parabens and concluded they were safe at levels up to 25%. Typically they are used at 0.01 to 0.3%.
In December 2005, the CIR decided, after reopening the assessment in September 2005, that they did not need to change their previous results on their safety.
A study was published in 2004 in the Journal of Applied Toxicology that found parabens in breast tumors. It did not show that they caused cancer, however.
Because of all the controversy and because companies hire scientists to do studies proving the ingredients that they used are safe and the lack of ingredient regulation, I stay away from them whenever possible. There is no proof that they are harmful, but there's enough evidence that makes me question them being in my products. I choose to go the more natural and organic route because it it better for you and your body, but if you aren't convinced then there's no reason to stop using your products.
Do your research and next time you see your esthetician, ask about parabens. Read books and articles from reliable sources. If any information changes I will be sure to post it. :)