According to the Environmental Working Group...
"Laboratory tests of canned infant formula conducted by the Food and Drug Administration (FDA) and a certified commercial laboratory reveal that a plastics chemical called bisphenol A (BPA) leaches from metal can linings into formula at levels which, according to new EWG analyses, would expose some bottle-fed infants to BPA in excess of doses that caused serious adverse effects in animal tests."
Shockingly, this article has an August issue date, but I never heard of it before.
See the full article here I'm so glad I almost exclusively breast-fed my kids. ::shudders::