Like others have said:
Step 1: Get them out of the attic.
Step 2: Check out the garments - some might still be 'good' - others might be in the 'what was I thinking?' category - others might have disintegrated
Many fabrics do just fine when stored - the yank/tear/rip/tug test is quite effective to see how strong a fabric still is.
How I do the test: I grab hold of two spots on a piece about six to ten inches apart - depending on what it is - and give a firm tug/yank on it - if nothing happens - then I consider it usable - if it comes apart/tears/shreds - it's discarded.
Elastics are notorious for giving up in heat.