Mark: Plastic-foam cups, which contain environmentally harmful chlorofluorocarbons, should no longer be used; paper cups are preferable  Styrene, a carcinogenic by-product, is generated in foam production, and foam cups, once used, persist indefinitely in the environment  Tina: You overlook the environmental effects of paper cups  A study done 5 years ago showed that making paper for their production burned more petroleum than was used for foam cups and used 12 times as much steam, 36 times as much electricity, and twice as much cooling water  Because paper cups weigh more, their transportation takes more energy  Paper mills produce water pollution, and when the cups decay they produce methane, a gas that contributes to harmful global warming
So they are a worse choice
Foam cups are somewhat more acceptable to consumers than paper cups because of their better insulating qualities.