safe materials?

i have a bunch of little skeins of strings. ( like a bag the size of my head mind you these are old my grandma gave me them years ago and she is a crafty lady and i think it’s appropriate to say there older than me ) I’m not too sure if they will mold i’ve never had any do that, even left in the shower for god knows how long. It dose say will boil on the wrapping. it dosent say what it’s made out of.

any input on if you think it’s safe would be helpful.