What it is: Bisphenol-A, or BPA for short, is a chemical found in some, but not all, hard plastics and plastic linings.
How it might harm: In animal studies, BPA has been shown to suppress a hormone that interacts with insulin – which helps us metabolize sugar – suggesting BPA might lead to insulin resistance and diabetes. In addition, BPA has shown to mimic estrogen in animals, a hormone that encourages weight gain among girls in puberty and later in life.
In addition to the animal studies, a study of 1,326 grade-school students published in PLoS ONE found those with BPA levels in their urine were two to five times as likely to be overweight than those with normal levels.
How to avoid it: Look for canned products, kids toys and water bottles that have “BPA free” on the label. Another trick is to avoid plastics with the recycle codes 3 or 7, as many such plastics have BPA.