Plastics are classified by their "resin identification code"—a number from #1 to #7 that represents a different type of resin. That number is usually imprinted on the bottom of your container; flip it upside down, and you'll see a recycling triangle with the number in the middle.
Here's a quick breakdown of plastic resin types:
#1 polyethylene terephthalate (PET or PETE)Examples: Disposable soft drink and water bottles
#2 high density polyethylene (HDPE)/Examples: Milk jugs, liquid detergent bottles, shampoo bottles
#3 polyvinyl chloride (V or PVC)Examples: Meat wrap, cooking oil bottles, plumbing pipes
#4 low density polyethylene (LDPE)Examples: Cling wrap, grocery bags, sandwich bags
#5 polypropylene (PP)Examples: Cloudy plastic water bottles, yogurt cups/tubs
#6 polystyrene (PS)Examples: Disposable coffee cups, clam-shell take-out containers
#7 other (plastics invented after 1987; includes polycarbonate, or PC, and polylactide, or PLA, plastics made from renewable resources as well as newer plastics labeled "BPA-Free")Examples: Baby bottles, some reusable water bottles, stain-resistant food-storage containers
What To Buy:
#2 HDPE, #4 LDPE and #5 PP: These three types of plastic are your best choices. They transmit no known chemicals into your food and they're generally recyclable; #2 is very commonly accepted by municipal recycling programs, but you may have a more difficult time finding someone to recycle your #4 and #5 containers.
#1 PET: Fine for single use and widely accepted by municipal recyclers; avoid reusing #1 water and soda bottles, as they're hard to clean, and because plastic is porous, these bottles absorb flavors and bacteria that you can't get rid of.
PLA: plastics made from renewable resources such as corn, potatoes and sugar cane and anything else with a high starch content; although you can't recycle these plant-based plastics, you can compost them in a municipal composter or in your backyard compost heap.
Plastics to Avoid:
#3 PVC: Used frequently in cling wraps for meat, PVC contains softeners called phthalates that interfere with hormonal development, and its manufacture and incineration release dioxin, a potent carcinogen and hormone disruptor.
#6 PS: Polystyrene-foam cups and clear plastic take-out containers can leach styrene, a possible human carcinogen, into food.
#7 PC: The only plastic made with bisphenol A, polycarbonate is used in baby bottles, 5-gallon water-cooler bottles and the epoxy linings of tin food cans. Bisphenol A has been linked to a wide variety of problems such as heart disease and obesity.