Bisphenol A (BPA) is a chemical building block used to make polycarbonate plastics -- the clear, tough material still found in some baby bottles. While the Food and Drug Administration continues to study BPA, there are concerns that BPA bottles could leak this chemical into the baby's drink, which could cause hormone disruption. Looking for an alternative? There's a new glass bottle from Lifefactory, which wraps a hi-tech silicone sleeve around a glass bottle, preventing slipping or breakage. The bottle is made of borosilicate glass that can be safely moved from the freezer to boiling water without fear of shattering.