Subject: Mouthwash + Polystyrene = Small lump of plastic???

I was recently reading the back of my mouthwash bottle, and it said "Avoid 
contact with plastics containing Polystyrene" and i couldn't resist pouring 
some onto a piece of polystryene i had...a few days later it had turned into a 
small hard piece of plastic that smelt of mouthwash. I'm wondering what 
happened, and why it does this... the ingredients in the mouthwash are:

Water, Isopropyl Myristate, Mentha Arvensis, Eugenia Caryophyllus, Sorbitol, 
Sodium Saccharin, Sodium Phosphate, Sodium Flouride, Cetylpyridinium Chloride, 
Triclosan, 2-Bromo-2-Nitropropane-1, 3-Diol, Cl 42053, Cl 42090, Cl 47005, 
Cl61565

Also, i was wondering why this type of plastic glue, also seems to do the same 
to polystyrene, but it dissolves it in a few seconds.

Re: Mouthwash + Polystyrene = Small lump of plastic???