Some ring pulls are indeed Aluminium and some steel .........if attracted to a magnet should be OK although some stainless steel does not attract to a magnet but i dont know why

Air Con element ...........it would sure make me ill if it was heated ......if its cold its probably ok but as I live in UK and dont have such filters i cant give you a long term answer

Basically if its Aluminium I avoid all contact

REFERENCE the Plumber ,,,,,,,,his main exposure will have been LEAD so plumbum will be important BUT he also is/was an alchoholic this fries brains and even Homeopathy cant reverse that kind of damage