I don't think so. For microbiological issues as long as they are covered by your hairnets and your staff is washing their hands any time they interact with the ear plugs you should be fine.
So the long answer is yes if they are not properly handled they are a microbio risk. However with proper training, proper hairnet covering, proper hand washing you will mitigate that risk through your GMP program.
As for storage I used to store mine right in my locker hanging on the coat hook at the pasta factory I worked in. Some of the non-disposable ones I've seen came with a holder but then you should require people to clean them every so often. I like disposable personally then you don't have to store them you can have them in dispensers next to the hairnets and beard nets.
Also you can get, as I'm told, a vending machine style piece of equipment that an employee enters their employee number and can have dispensed a hairnet/beard net/ear plug as required and they have a certain allotment they are allowed to remove per day or week. That way they aren't blowing threw disposable equipment. Personally I don't like that idea because then they have to see a supervisor if there is a rip in their hairnet or if they need more of something because it fell on the floor or whatnot.
I always advocate just getting a new one if there is any question on disposable equipment (and I'm not paying for it )
Just some thoughts and ideas on your topic