With health risks of BPA plastic reported in the press in recent years, many manufacturers have made the switch to BPA-free plastics. But emerging science suggests the BPA-replacement chemicals may be just as harmful.

"BPA-free" is the buzzword of choice for water bottles and plastic packaging. Bisphenol A (BPA)-the chemical that hardens plastic food containers and is in the lining of metal cans to prevent corrosion-has gotten bad press for having a harmful estrogen-mimicking effect, which may cause early puberty and lower sperm counts, even raise your risk of obesity, diabetes and some cancers (breast, ovarian, testicular, prostate).

Many manufacturers have made the switch to BPA-free. But are those BPA-free plastic water bottles better? Now, emerging science suggests the BPA-replacement chemicals may be just as harmful. In one study in Environmental Health Perspectives, researchers looked at over 450 plastic containers, including BPA-free ones, and found almost all leached chemicals that imitate estrogen.

Bisphenol S (BPS) and bis­phenol F (BPF) are the two most common replacements for BPA. Research in animals shows that both chemicals disrupt hormone balance comparably to-and sometimes worse than-BPA. High levels of BPS may even promote weight gain. The upside of the replacement BPS is that it may be less likely to leach into your food or beverage when heated in the container (as opposed to BPA, which is highly sensitive to heat).

Bottom Line: BPA-free does not mean chemical free. And although the evidence is building against BPA substitutes, more research is needed to assess the effects on human health. To avoid these chemicals in your food, look for food packaged in glass and aseptic packaging (like Tetra Pak) and use glass and stainless steel for food storage at home. And never heat food in any type of plastic container.