What Do Those Numbers on the Bottom of Plastic Containers Mean?

As part of my pack-rat ways, I am an avid recycler.  With my "obsession" with recycling, I have come to learn about the different numeric symbols found on the bottom of plastic containers in the United States.  I had always wondered what those numbers meant.  Those numbers are a great way to determine the kind of plastic the container is made of.  I didn't even think about the kinds of plastics that I was using until I became pregnant with my first child.  It was during that time the controversy surrounding bisphenol-A (BPA) came about.  I suddenly wanted to know what could contain BPA.  Learning about the numeric symbols helped me to understand what kind of plastic my containers contain.

What do these numeric symbols look like?

Numeric symbols found on the bottom of plastic containers

Most plastic containers in your home today probably contain one of these symbols on the bottom.  These symbols are technically called a "resin identification code."  According to the Environmental Protection Agency (EPA), "The resin identification coding system for plastic, represented by the numbers on the bottom of plastic containers, was introduced by the Society of the Plastics Industry, Inc. (SPI), the plastics industry trade association, in 1988. Municipal recycling programs traditionally target packaging containers, and the SPI coding system offered a way to identify the resin content of bottles and containers commonly found in the residential waste stream. Plastic household containers are usually marked with a number that indicates the type of plastic. Consumers can then use this information to determine whether or not certain plastic types are collected for recycling in their area. Contrary to common belief, just because a plastic product has the resin number in a triangle, which looks very similar to the recycling symbol, it does not mean it is collected for recycling."  The EPA further explains the abbreviations listed under the symbols below:

SPI Resin Identification Code	1	2	3	4	5	6	7
Type of Resin Content	PET	HDPE	Vinyl	LDPE	PP	PS	OTHER

PET - Polyethylene Terephthalate HDPE - High-density Polyethylene LDPE - Low-density Polyethylene

PP - Polypropylene PS - Polystyrene Other - Mixed Plastics

The Learning Channel actually put together a very easy to understand explanation of the different codes:

"#1 - PET or PETE: polyethylene terephthalate is used in many soft drink, water, and juice bottles. It's easily recycled, doesn't leach, and accepted by most curbside municipal programs and just about all plastic recycling centers.

#2 - HDPE: high-density polyethylene is used in milk jugs, detergent and shampoo bottles, and, because it hasn't been found to leach, will replace polycarbonate in a new Nalgene bottle (more on that in a sec). It has also has not been found to leach, and is widely accepted and easily recycled.

#3 - PVC: Vinyl or polyvinyl chloride is a bad, bad plastic. Soft PVC often contains and can leach toxic phthalates, and can also off-gas chemicals into the air. It's used in some cling wraps (yikes!), many children's toys, fashion accessories, shower curtains, and detergent and spray bottles. To top it off, PVC isn't recyclable, either.

#4 - LDPE: low-density polyethylene is used most plastic shopping bags, some cling wraps, some baby bottles and reusable drink & food containers. It hasn't been found to leach, and is recyclable at most recycling centers (and many grocery stores take the shopping bags) but generally not in curbside programs.

#5 - PP: polypropylene can be found in some baby bottles, lots of yogurt and deli takeout containers, and many reusable food and drink containers (you know, the Tupperware- and Rubbermaid-types). It hasn't been found to leach, and is recyclable in some curbside programs and most recycling centers.

#6 - PS: polystyrene is used in takeout food containers, egg containers, and some plastic cutlery, among other things. It has been found to leach styrene--a neurotoxin and possible human carcinogen--and has been banned in cities like Portland, Ore. and San Francisco. Still, it persists and is not often recyclable in curbside programs, though some recycling centers will take it.

#7 - Everything else, and this is where the waters get a bit murky. First, and perhaps most notably, #7 includes PC, or polycarbonate, which has been making headlines lately because it's used in Nalgene's reusable water bottles and has been found to leach bisphenol A, a hormone disruptor that mimics estrogen; as such, Nalgene is switching to HDPE, a less harmful plastic."

The following "smart plastics guide" is an easy to print up .pdf file that you can hang on your refrigerator for reference before heading out to recycle your plastic.

After reading about the different identification codes, I became nervous whenever I saw a product labeled with a #3, #6 and #7.  I actively began using less plastic when it came to food preparation and storage.  I especially began to rethink heating any food in any plastic containers.  It is during high heat that many plastics can "leach" onto food.  I started using more glass containers and began throwing out containers that had any of those three codes.  I am also more aware when I go out to eat to look for restaurants reheating food covered in plastic wrap.  Rather than using plastic wrap, I now use a glass plate as a "cover" when reheating something.  There are so many alternatives to plastic these days that I would rather change my behavior than risk something happening to my children.