You may see this label on reusable water bottles or plastic containers. BPA -(Bisphenol - A) is used in plastics and resins. You can tell if a container has BPA in it if it has a 3 or 7 found within a recycling sign.

However some unlabelled containers may also have BPA.

BPA can be found in canned goods, eye glasses and cds. BPA can also seep into food if containers are microwaved. When BPA is accumulated in women, it can be passed onto their children through breast milk. Studies have found that BPA could affect children's brain development. BPA has been banned from infant formula packaging and baby bottles. BPA is also a form of estrogen and can influence your hormal balance and could be an endocrine disruptor. BPA has also been found to increase risk to breast cancer, prostate caster, infertility and Type 2 Diabetes. 

 

Sources: http://www.breastcancerfund.org/clear-science/radiation-chemicals-and-breast-cancer/bisphenol-a.html?referrer=https://www.google.com/ (Other BPA studies can be found here).