Hello Concerned Mommy,
I have had three children in the last 4 years and have done extensive research on products we bring into our home. Here is a partial of a write up on memory foam.
-Recent findings also showed that petroleum-based foam mattresses may be a source of cancer-causing chemicals. During use, all these foams break down in dangerous by-products: toxic dust under the bed and formaldehyde gas in the air.
-Additionally, the average mattress seems to contain around a pound of fire retardants called PDBE (polybrominated diphenyl ethers), already banned in Europe and the US. These PDBE have only been recently banned (January 2005) so the mattress you currently sleep on probably still contains them. Tests show that these chemicals may be especially toxic to kids, potentially affecting their hearing, memory and even intelligence after sleeping on PDBE-treated cribs.
If I were you I would get rid of the mattress. I know that it cost money, but is it worth the risk? I am glad you are concerned, but with that concern comes your motherly instinct to get rid of it. Anything that leaves an un-natural smell cannnot be healthy.
Hope this helps,
Mommy of 3