Babies throw stuff -- including their sippy cups. That's why most parents buy plastic everything for little kids. But in 2012, the Food and Drug Administration banned the use of polycarbonate resins in baby bottles and cups from the United States market, because polycarbonate contains bisphenol A, better known as BPA. Because BPA, a potential toxin, can leach out of plastic cups over time or under certain conditions, your baby should not drink from them.
Manufacturers use BPA to strengthen plastic in hard plastic polycarbonate baby bottles and cups. Food manufacturers use BPA as part of epoxy resins, to line the inside the canned goods, to decrease bacterial growth and to keep cans from rusting. Use of polycarbonate containing BPA for baby bottles and cups and other products dates from the 1960s. Manufacturers began voluntarily removing BPA from baby bottles and cups starting in 2008; in 2012, the U.S. Food and Drug Administration formally banned the use of polycarbonates in the drinking items.
BPA acts as an endocrine disruptor and can have side effects that mimic those of the dominant female hormone estrogen. Most of the evidence against BPA comes from animal clinical trials, not from human studies. No studies in children have proven that BPA has long-term health effects. In animal studies, however, low levels of BPA stimulate early breast development and early puberty onset in females and decrease testosterone production, which affects sperm production, in males. In offspring whose mothers received BPA during pregnancy, behaviors changed, including increased aggression and hyperactivity, according to a Canadian article published in the January 2009 issue of Paediatric and Child Health. In a Centers for Disease Control and Prevention study published in the April 2005 issue of Environmental Health Perspectives, 95 percent of adults had measurable amounts of BPA in their urine.
If BPA stayed put in plastic cups, it wouldn't pose any risk. But plastics break down over time, allowing BPA to leach out into whatever is in the cup, such as your baby's milk. Putting polycarbonate cups in the microwave, washing them in the dishwasher or putting hot drinks or foods into them can all cause the plastic to weaken more rapidly and break down, releasing BPA, the American Academy of Pediatrics advises.
Reading the Bottoms
Manufacturers can no longer make sippy cups or baby bottles from polycarbonate containing BPA, but you can still find these cups at garage sales or at thrift shops. Plastic products generally have a code on the bottom that tells you what type of plastic from which they're made. But in the case of polycarbonate, manufacturers use the number 7, which means "other." Some polycarbonate cups print the letters "PC" on the bottom. Not all cups with the number 7 on the bottom contain BPA. The safest cup for your baby is one that you buy new and that specifically states it's BPA-free.