M.C.
I bought an organic mattress for my son so I did not have to worry about chemicals. 4 years later it is still very firm...and my brother and SIL are taking it for their new baby.
If you want to get rid of it, call a local animal shelter or kennel to donate. Larger /older dogs love crib mattresses for dog beds :-) I donate old lumpy pillows to the dogs too.