What do the numbers on plastic recyclables mean?

It may be old news to mention that recycling is a great way to reduce environmental footprint. But the fact remains, many of us are still perplexed by the numbers that appear on our domestic plastics. 

Let the demystification begin....

The resin code numbering system was put in place in 1988 by a trade organization called The Society of the Plastics Industry (SPI). The system was designed to make the sorting of plastics easier as well as to indicate potential toxicity. Most U.S. recycling centers accept plastics numbered 1 and 2, which account for 96% of bottles and plastics in the country. As recycling technology develops, more and more municipalities are accepting numbers 3, 4, and 5. 

1 - It'd be neat if "Pete" were some long-haired plastic-collecting dude, but the acronym stands for polyethylene terephthalate, also known as PET. They are considered safe, though recent studies suggest that the reuse and heating of these porous plastics may not be advisable. Number ones include:

• soda bottles
• water bottles
  
• clear beverage bottles 

2 - High density polyethylene, also generally safe, is found in:

• "cloudy' milk bottles
• detergent containers
• juice containers
• butter tubs
• shampoo bottles

3 - Caveat emptor: Do not microwave! Polyvinyl chloride, or PVC are known to contain phthalates that interfere with hormonal development. You'll find PVCs in:

• food/cling wrap
• cooking oil
• plumbing pipes

4 -  Low density polyethylene, considered safe, is found in:

• grocery bags
• bread bags
• squeeze bottles 
• some food wraps

5 - Rigid plastics, or polypropylene are known to be reasonably safe. You'll find the "5" on:

• some baby bottles
• water bottles
• ketchup
• medicine bottles
• syrup
• straws

6 - Increasing evidence suggests that Polystyrene, or Styrofoam, leaches dangerous chemicals, especially when heated. These plastics are difficult to recycle. They include:

• disposable plates, cups
• meat trays
• egg cartons
• carry-out containers

7 - The "everything else" category: Polycarbonate, BPA, including many corn-based plastics, and mixes of PET, PP, and HDPE. Eye these cautiously as toxins are cumulative. Some miscellaneous plastic items:

• iPods
• computer cases
• baby bottles
• food storage containers
• Nalgene bottles
• medical instruments