What I discovered recently about plastic is that my spit dissolves them. Not like ice in water, not that quickly... but a couple times in the fall I spit into a nearby plastic cup while laying on the couch watching tv ( I hate swallowing my spit, spit like when you get a heave up from your lungs... if you are chelating or doing a parasite cleanse you probably experience that, it's full of toxins, possible parasite larvae, don't swallow it)... and forgot to rinse it out and the next day... the spit all dried up in there either would not rinse off (seemed to be permantly attached to the plastic) or else if it did rinse off it left a nice etched imprint. In one cup it was literally a measurable depth, not much but measurable. This was very hard thick plastic, 2 different cups. I threw them out duh.

But... before you judge me as weird you might want to test your own spit on different plastics because I have looked into it and it's actually known that saliva slowly dissolves some plastic materials, including dental composites. I found that out a while back by digging around the net. That's maybe why your dentist won't guarantee his work to last a lifetime. You are eating it little by little everyday. If you get your kid's teeth sealed the lifetime of the sealer is only about 4-5 years or so. What do you think happens to it?

doesn't seem to affect glass though.