
These are numbers commonly seen on the bottom of plastic containers. They are important because the codes tell us what type of plastic is used and I guess tells the recycling agencies how to sort them. The key to understanding them is to know the impact they have on the environment and on our health.
Briefly, Number one is Polyethylene Terephthalate. You find this on most single use drinking bottles. The concern is the buildup of bacteria due to insufficient cleaning or reuse. They are the most viable for recycling. They also litter our streets and go out to the ocean and become floating waste.
Number 2 is High Density Polyethylene used in sport bottles, cloudy colored milk jugs, cereal box liners, shampoo bottles, and many other containers. Very recyclable and not harmful.
Number 3 is bad. Polyvinyl Chloride is a controversial plastic. They should be non-food storage only. Number 3 has been named “toxic plastic” due to softeners (DHEA) that may cause cancers and other health issues.
Number 4 is OK. Low Density Polyethylene used in making bread bags, frozen food bags, and squeezable bottles. It doesn’t transmit any known chemicals into food and can be recycled.
Number 5 is fine as well. It is made of Polypropylene and not as recyclable as numbers 1 and 2 but is safe and found in yogurt containers, syrup bottles, straws and medicine bottles. Lately, many of the newer bike bottles I’m seeing are made from this plastic.
Number 6 is bad news. Polystyrene is used in making styrofoam, plastic tableware, and take-out containers. This product may leach styrene compounds- a possible carcinogen- and disrupt hormonal functioning.
Number 7 is not good at all. A clear, hard, shatterproof plastic made with Polycarbonate, specifically Bisphenol-A or BPA. It may pose serious health risks. The popular and colorful Nalgene water bottles were made of this and recently underwent a change where they are now BPA-free. Your Sparkletts and Arrowhead 5 gallon water bottles are made from this and continue to be manufactured with Bisphenol-A. When warm these bottles can leach BPA into water or food. Bisphenol-A is a synthetic hormone and may be linked to cancers, obesity, diabetes, and premature developmental problems.
I hope this is a helpful guide. Personally, I wish to not use these and prefer glass and stainless steel for water and use only plastics that are safe and recyclable for food storage when necessary.