Chicago on Wednesday became the first U.S. city to adopt a ban on the sale of baby bottles and sippy cups containing the chemical BPA.

The Chicago City Council approved the ban on a 48-0 vote and a spokeswoman for Mayor Richard M. Daley said he intends to sign it. The ban is slated to take effect Jan. 31, 2010.

BPA, or Bispheol A, is a chemical used to make plastics.  Exposure to it is known to mimic hormones and cause a host of chemical disruptions as well as reproductive harm in the body.  It has been in the news frequently in the last year or so, concerning manufacturing of water and baby bottles; it’s use in the production of PVC, flame retardants and the coatings of the insides of food and beverage cans, among other things.

Other places to ban BPA: Suffolk County in New York, Minnesota and the entire country of Canada.

Despite the obvious, proven effects BPA has on humans, the FDA and the chemicals industry claim products with the chemical are safe.

Chicago’s ordinance requires retailers to post notices declaring that products they sell do not contain BPA. Violators could be fined up to $100 or more per offense and could lose their licenses.

BPA — or bisphenol-a to you nerdy types — has been in the news a lot lately. Wal-Mart and Toys ‘R Us are the latest to listen to consumer demand (go free market!) and are starting to pull baby bottles containing BPA. Canada’s push for a full ban is moving forward, and more and more companies are starting to manufacture BPA-free alternatives. Why? Because experiments on lab animals has linked BPA to “changes in the brain, early puberty, and possible tumors.” Not exactly something you want to make it’s way into your baby’s body (or yours for that matter — Nalgene, a manufacturer of reusable drinking bottles, is also starting to phase out BPA in its production process).

We’re certainly not ones to shy away from a trend when there’s good science and our kids’ health involved, so we’ve convinced Medela to give away a Breastmilk Feeding & Storage Set containing three BPA-free bottles, lids and nipples, to 5 of our lucky readers to get started down a toxin-free path. (Pssst, we have a sneaky feeling these bottles would be just fine for formula feeding as well.) The entry form is here.

Ed. note: The Imperfect Parent did not receive any compensation for this post

A seemingly new possible hazard found in “modern life” — if you give your baby expressed breast milk or formula in a plastic bottle, hormones may be leeching out of the plastic and into the liquid.

What chemical/hormone is it?

[I]n a news briefing Thursday, a separate group of university and government scientists said they have reached their own conclusion -– that there is ample reason to fear that the chemical is, in fact, causing adverse human health effects -– including possible abnormal development of reproductive organs and predisposition to cancer.

The chemical in question, bisphenol A (BPA), the basic building block of polycarbonate plastic, also mimics the female hormone estrogen. An estimated 95 percent of Americans have it flowing through their bodies – and Texas is a major producer of the chemical.

What’s a mother to do?

There are already indications that the public is taking notice. Baby bottles and sippy cups made without BPA are on the market; a popular baby book has recommended buying products free of BPA; and Norway has proposed a ban on BPA.

Born Free bottles claim to be BPA free, available at Target. Also, colored Gerber and Evenflo bottles are promoted as BPA free, according to www.healthobservatory.org, who has an internet brochure available on what’s safe and what’s not.