According to the IICRC S520 Standard and Reference Guide for Professional Mold Remediation mold is defined as "a common term for filamentous fungi, often seen as a superficial or 'wooly' growth of long chains of fungi cells formed on damp organic materials. Toxigenic molds may produce a potentially harmful substance called a mycotoxin. Mold growth can degrade materials and present potential risks to humans."
It is also suggested in the same reference guide that any porous surface in a Category 3 Water Loss (where biohazards are possible) usually cannot be effectively remediated and restored to a pre-loss condition due to staining and other problems. In this instance, carpet and underlying padding must be disposed of.