http://www.dentalbuzz.com/2014/03/04/crest-imbeds-plastic-in-our-gums/

Crest toothpaste embeds plastic in our gums

MARCH 4, 2014 BY TRISH WALRAVEN

Did you know that polyethylene is the most common plastic in the world?
It is used primarily for containers and packaging, such as these bottles
and plastic grocery bags, and has been a concern for the environment
because polyethylene lasts practically forever and isn?t biodegradable.
It only breaks down into smaller and smaller particles until you can?t
see it anymore. That?s why a couple of states are trying to ban it in
body scrubs and dental products.