According to the U.S. Environmental Protection Agency (EPA), absorbent or porous materials may need to be thrown away if they become moldy because mold can grow on or fill in the empty spaces and crevices of porous materials, making the mold difficult or impossible to completely remove. Porous materials that are likely culprits for harboring mold include carpeting, wallboard, ceiling tiles, wallpaper, fabric, upholstered furniture, and last but not least: your memory foam mattress.
In fact, a class-action lawsuit was filed in October of 2008 in U.S. District Court, Northern District of California, San Jose Division, against several manufacturers who sell the Sleep Number bed including Select Comfort, Bed Bath & Beyond, and Sleep Train - all for exhibiting signs of mold inside the pillowtop bed. The suit lists 17 causes for action: negligence, breach of express warranty, intentional misrepresentation, and more.
California-based bedding manufacturer Nest Bedding recently published an article that explains, "If your mattress is on the floor, on a solid, non-breathable base, or the slats are too plentiful or too wide, or simply too close together, the mattress cannot breathe properly and you accumulate moisture and eventually mold." In simple terms, the moisture comes from your sweat. Everyone sweats in their sleep - some up to a pint during the course of an evening.
Nest continues, "If you are sleeping hot, consider replacing your bedding with natural, synthetic-free bedding. If you use down and feather comforters, consider switching to wool as it's better at temperature regulation. If you are sleeping hot and have a memory foam mattress, consider adding a wool topper or switching to an all-natural organic mattress comprised of natural cottons and wools, which breathe much better."