Here's another reason to invest in a reusable coffee cup: disposable plastic lids may be bad for you. Disposable coffee cups use plastic lids made from rigid Styrofoam -- a No. 6-grade plastic -- that has the chemical bisphenal A (BPA) in it. When you sip your hot latte through a plastic lid, you're slowly sipping chemicals, too. In addition to investing in a reusable mug, you can avoid BPA in other plastic containers by simply looking at the recycling symbol. If you see Nos. 1, 2, 4 or 5, the product has low or zero BPA in it.