Probably no long term study done because this is only really coming to light now. I am sure there will be one starting up soon. Currently it will just be reviewing what is actually in it and the microbial part such as E. coli amounts.
Pink slime is safe for consumption but the problem is that its just disgusting.
By the way, I have known this for at least a year now..
Amazing that the public has been notified about this just recently..