The plastic bag is an icon of convenience culture, by some estimates the single most ubiquitous consumer item on Earth, numbering in the trillions. They're made from petroleum or natural gas with all the attendant environmental impacts of harvesting fossil fuels. One recent study found that the inks and colorants used on some bags contain lead, a toxin. Every year, Americans throw away some 100 billion plastic bags after they've been used to transport a prescription home from the drugstore or a quart of milk from the grocery store. It's equivalent to dumping nearly 12 million barrels of oil.
The problem with plastic bags isn't just where they end up, it's that they never seem to end. "All the plastic that has been made is still around in smaller and smaller pieces," ... unless they've been incinerated -- a noxious proposition -- every plastic bag you've ever used in your entire life...still exists in some form, even fragmented bits, and will exist long after you're dead.
Yay! They damage our infrastructure, contribute to environmental degradation, kill things and, best of all, last nearly forever!
Oh well, at least some of the carbon we extract is being buried...