Breast implants - a very interesting article. Definitely read this if you are thinking seriously about implants: http://www.implanttruth.jshood.com/article.html
Unfortunately you can't copy and paste the relevant bits here, but even if people skip the history and scrol down to about the last 8 paragraphs...the bit about bacterial colonisation turning the implant into a 'bad aquarium' in 5-6 years in 80% of cases and in some people turning black - yuck! The scary thing is you probably woudn't even know if it was doing somthing nasty.