There are some potential hazards but there is no question to the quality sleep you will get compared to such risks. Some memory foams emit a distinct chemical odor when new, which many people complain about and some say it is comparable to the smell of paint. This odor gradually goes away with airing but some may remain sensitive. Acetaldehyde, acrylonitrile, carbon monoxide, oxides of nitrogen and hydrogen cyanide are namely a few of the hazardous decomposition products associated with memory foam. The emission of these chemicals may cause irritation of the respiratory system.
 It was discovered that material used to make memory foam mattresses, polyurethane, can be highly combustible, so in order to make these mattresses less combustible manufacturers added polybrominated diphenyl ethers (PBDE), an organobromine compound that is used as a flame retardant. However, questions arise about the long-term risks associated with PBDE.
Other objectionable features of the memory foam mattress are:

• Retains body heat – the mattress absorbs and in turn fails to release a person’s body heat, therefore resulting in a surface that is unnaturally warm.
• No adjustable firmness – memory foam mattresses provides no adjustable firmness compared to airbeds and waterbeds.  If one wishes to change the level of firmness, one would have to purchase a mattress topper that would more appeal to their choice of firmness.
• Unable to use electric blanket – memory foam manufacturers prohibit the use of electric blankets, they advise that destroy the memory cells over a long term period.
• May not be suitable for light weight people – most people light weight (110 lbs. or there about) regularly complain that they don’t sink into the foam. Hence they don’t experience the relaxing comfort of the foam.

Be sure to do your research so you know what to ask your retailer