Here's some language from the message to Congress that explains the concern over BPA:
BPA was first synthesized as an estrogen replacement therapy in the 1930s but was discarded in favor of other therapies. In the 1940s, chemists discovered they could use BPA to make plastic. Now BPA can be found in baby bottles, water bottles and food storage containers. It is also used the lining of metal food cans, including infant formula cans.
BPA is of particular concern to moms because even minuscule amounts – parts per billion or parts per trillion – have been shown to cross the placenta and disrupt normal prenatal development. Early life exposure to BPA has been linked to a host of developmental problems, such as breast cancer, prostate cancer, obesity, early onset puberty, abnormal brain development , hyperactivity, and the genetic defect that causes Down’s syndrome. The CDC found BPA in 93% of all Americans and the scientific literature points to food as being the major route of exposure.