Recycling plastic sometimes seems like a minefield.
It should be easy, right? Plastic shampoo and soda bottles go in the blue bins, wispy plastic grocery bags don't - but what about take-out containers?
Many to-go containers are similar to plastic bottles, but they're often caked with food. If it's too dirty, the recycling plant might just send it to the landfill.
Adding to the confusion is that whether you can recycle any given plastic - or any plastic at all - depends entirely on your local government's recycling program.
Many cities recycle plastics only with a tiny embossed number 1, 2, and 6 on the item, or some other combination of those numbers.
But what do they actually mean?
The numbers correspond roughly to the type of resin used the plastic itself. (Though even within these categories, there's a huge amount of variation.)
Most to-go food containers - particularly the clear, clam-shell type - are made out of plastic No. 1, just like soda bottles. These are pretty easy to recycle, and most municipalities will, after you've rinsed them and completely removed any stickers.
While containers making their way from your street to the plant, any bits of food on them can spur bacterial growth. The containers can be sterilized, but that adds time and energy to the process. Many plants would rather just chuck the dirtiest plastics than waste resources on cleaning them thoroughly.
Cardboard pizza boxes and paper Chinese takeout containers don't hold up well to rinsing, so you have to rip up the containers to separate the soiled from pristine parts (then recycle the latter).
Styrofoam, however, is another matter.
It's is so hard to recycle that New York City tried to ban it in 2013, but failed when the industry won a lawsuit two years later.
Most places won't pick up styrofoam, also known as plastic No. 6, with your regular recycling. But depending on where you live, there might be a drop-off facility.
Of course, lots of take-out places are switching to biodegradable boxes.
Researchers from Singapore announced today they've created a new, biodegradable polymer derived from crustacean shells - so even if your city doesn't recycle plastic yet, it might soon.
The perhaps unsatisfying final verdict on takeout containers is that it's complicated. Check your local government's site for recycling information, look for embossed numbers that match the plastics it accepts, rinse those containers well, and chuck anything else.