On the other hand, what is there to lose if the price is low enough? I think the usual attack would be correct: mild detergent with lots of water and NO abrasion; then go with the acetone - I use the gentle cotton bud application with possible repeat applications & then followed by the aforementioned suds and water.
This looks to be a chloride/PVC conglomeration on the surface and have used dilute ammonia to some effect on these before, but not before trying the other methods out...
PS - I do not subscribe to the "infective" capacity of such reaction as the conditions that caused it must be there for subsequent coin(s) to develop their own versions....