Concerns about the effects of the chemical bisphenol-A have grown in recent years. The chemical can be found in the linings of cans and is used to make plastic bottles and containers. Half a dozen states have already banned it from children's products over fears that BPA mimics the effects of hormones. But the scientific community has not come to a clear consensus on how BPA affects human beings. Denise Grady, reporter for the New York Times, explains that the fight over what to do about BPA is now becoming political.