Is a plastic bottle with the number 7 on the bottom dangerous?

Question

Is a plastic bottle with the number 7 on the bottom dangerous?

Answer 1

Many plastic items are marked with a resin ID code – usually a number (1 through 7) or a letter abbreviation – which indicates a particular type of plastic. The code is typically found on the bottom of a container and is often displayed inside a three-arrow recycling symbol. Resin ID codes are used to help identify different plastics for recycling, but they do not provide guidance on the safe or intended use of a product and should not be used for this purpose.

For reliable information on using a plastic product or package, be sure to consult the packaging label and any additional instructions that may be provided.

  



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Who is Pete and why is his name on the bottom of a plastic bottle? You've probably seen the little triangles and numbers on the bottoms of plastic bottles. But what do all these little numbers and triangles mean?

The numbers are all about recycling. Because many plastics can be made cheaply, they are often used to make disposable items. This kind of use creates lots of waste. Recycling plastic is one way to reduce the amount of waste.

Before plastics can be recycled, they must be sorted. Many different kinds of materials are used as plastics, and most cannot be mixed, in the same way that oil and water can't be mixed. To help separate one kind of plastic from another, many items have a triangle printed on them, with a number inside. The numbers on your bottles tell you from what kind of plastic the bottle is made.

Many kinds of polymers are used, because for different uses, plastics with different properties are needed. Sometimes we need stiff plastics, and sometimes we need flexible ones. Sometimes we need transparent plastics, and sometimes we need plastics that aren't transparent.

Each number on a plastic object corresponds to a different kind of polymer from which the object is made. Each polymer has different properties because it has a different molecular structure. Below you can see a diagram showing which number corresponds to which polymer, and the chemical structure of that polymer.

  

poly(ethylene terephthalate) (PET)

Invented by J.R. Whinfield and J.T. Dickson, 1940.

Uses: clothing, plastic films, plastic bottles



  

high-density polyethylene (HDPE)

Invented by Robert L. Banks and J. Paul Hogan, 1951.

Uses: plastics of all kinds, high-strength fibers



  

poly(vinyl chloride)

Invented by Waldo Semon, 1926.

Uses: water pipes, LP records, vinyl car tops



  

low-density polyethylene (LDPE)

Invented by Eric Fawcett and Reginald Gibson, 1935.

Uses: plastic films, bags



  

polypropylene (PP)

Invented by Robert L. Banks and J. Paul Hogan, 1951.

Uses: fibers for rope, indoor-outdoor carpeting, plastics



  

polystyrene (PS)

Invented by Eduard Simon, 1839.

Uses: rigid plastics of all kinds, polystyrene foams



anything else, including items made

from more than one kind of polymer

Answer 2

i saw on the today show that any number higher than 3 is not good.

Answer 3

Most plastic containers are labeled on the bottom with a number from 1 to 7. The good numbers are 1, 2, 4 and 5. The bad numbers are 3, 6 and 7, which are apparently full of all kinds of nasty chemicals that can cause cancer and other serious health problems.