If the Recycle code on the plastic is 3 or 7, then don’t use it on foods. The chemical in 7, BPA, is bad news.
Which Plastics to Never Use with Food
Flip over your favorite plastic food storage container and check the recycling code number. If you spy a number 3 or 7, well, those containers should probably go to the craft room or garage to store buttons or screws rather than food. If there is no number listed, contact the manufacturer. (And to be fair to Tupperware, they do manufacture products that are not made of these plastic types.)
Recycling code number 7 includes several plastic types (it’s the catchall “other” category–see tips below) but it is predominantly polycarbonate. The problem with polycarbonate is that it harbors bisphenol A (BPA). Studies have shown that BPA damages the reproductive systems of lab animals by interfering with the effects of reproductive hormones and has other serious health effects. BPA’s capacity to cause these stems from its ability to mimic the human hormone estrogen–it has been linked to prostate and mammary gland cancers, early onset of puberty and reproductive-organ defects.