Canada's regulatory body, Health Canada, is the first in the world to declare Bisphenol A dangerous, the first step toward a ban. The chemical is used to make polycarbonate bottles, but also can be found in the linings of most tin cans.
Martin Mittelstaedt of the Globe and Mail writes "Independent researchers in dozens of studies have linked trace BPA exposures in animal and test-tube experiments to conditions involving hormone imbalances, including breast and prostate cancer, early puberty and changes in brain structure, particularly for exposures during key points of fetal or early neonatal development.
Until now, regulators in other countries have accepted the industry's assertion that BPA is harmless at the tiny, parts-per-billion type exposures from canned food and plastic beverage containers. A part per billion is roughly equal to one blade of grass on a football field, although natural hormones such as estrogen are active at far lower concentrations, around a part per trillion." ::Globe and Mail
UPDATE: see more information on beating BPA here.
Lots of TreeHugger on this subject: Hot Water + Polycarbonate Bottles = More Gender-Benders, Time to Pack In the Polycarbonates, MEC Nixes Nalgenes, Camelbak Introduces Genderbender Free Bottles and Gender Bender Chemicals Also Make You Fat