Short answers: it’s oil and once it becomes plastic, it never goes away.
Plastic is one more side of our multi-faceted addiction to petroleum. Every container, tool, chotchky, CD, you name it is one more demand for oil; foreign dependence or domestic pillaging.
Rethink~Reuse~Recycle is a great motto, to be followed in that order. Think about your choices before you make them. Take the canvas bag to the store (tip: keep them by the door or in the car). Is there an option with less packaging? Don’t fool yourself that it all gets recycled. Can you find it in paper, metal, or glass? Do you really need it?
But what of the stuff that escapes our careful plans? Doesn’t it wear out, break down, dissolve? Yes, to a point, but it will always be plastic, just very small pieces. Like much of what we discard, it will end up in the ocean. Bags look like jellies and are mistaken by turtles for food. Birds eat a variety of plastic items, starving to death with their bellies full. According to the UN Environment Programme, plastic debris causes the deaths of more than a million seabirds every year, as well as more than 100,000 marine mammals. Beginning at the bottom, looking like zooplankton, up the food chain it goes. Maybe someday an industrious bug, like the termite, will manage to begin digesting it, but for now, it’s just a killer. But out of sight, out of mind, right? So, after you read the wiki in the title link, read these:
The genie is out of the plastic bottle. What happens to it now is every consumer’s responsibility.