What is Mold?

Molds Generally

Molds are microscopic fungi that are found virtually everywhere. There are more than 100,000 species of mold and at least 1,000 species of mold are common in the United States. Most molds are benign and non-toxic to humans.

Mold plays an important role in the environment - molds break down dead material allowing nutrients to be recycled. The CDC reports that mold exist everywhere in small quantities. It can be found in the air and on many surfaces.

For molds to grow and reproduce, they need only a food source and moisture. Molds will feed on any organic material including leaves, wood, paper, or dirt. Mold growth is visible to the eye and is accompanied by a musty, earthy odor. Molds, both toxic and non-toxic, generally appear as black or gray patches, but it can also appear green, brown, or even white.

Household molds grow naturally in damp areas such as bathrooms and basements. Molds can also enter a building or home through ventilation systems, open windows and doors, or by attaching to clothing, shoes or even animals. Mold is unavoidable, but reducing moisture can make a building less conducive to mold growth. The most common indoor molds are Cladosporium, Penicillium, Aspergillus and Alternaria. The only toxic molds found indoors are two species of black mold: Stachybotrys Chartarum and Memnoniella.

Mycotoxin-Producing Mold (Stachybotrys & others)

Stachybotrys Chartarum

Stachybotrys Chartarum, also known by its synonym Stachybotrys atra, is a greenish-black fungus. It is the most common type of mycotoxin-producing mold, but it is still rather uncommon to find in homes. S. atra typically grows on water soaked materials containing cellulose such as wood, paper, and cotton products. Stachybotrys can look slimy, sooty, or even like grayish white strands depending on the level of moisture and the length of time it has been growing. Many other common indoor molds can look similar to Stachybotrys (including Cladosporium and Aspergillus) so testing must be done to conclusively identify Stachybotrys. If the black mold is growing on a material that does not contain cellulose, it is unlikely that Stachybotrys is present.

Memnoniella

Memnoniella is the only other black mold that is known to produce mycotoxins. Memnoniella is much less common than Stachybotrys. Both of these molds typically grow on water soaked materials containing cellulose.

What Are Mycotoxins?

Mycotoxins

Mycotoxins are poisonous substances. Mycotoxins are the metabolic by-product of mold. Humans can be exposed to mycotoxins through inhalation, ingestion or skin contact. The mycotoxins produced by molds vary depending on the mold and on the materials on which mold grows.

Effects of Exposure to Mycotoxins

There is much debate within the scientific community over the effects of mycotoxins. There is also debate as to whether such mold should be referred to as "toxic". Studies endeavoring to connect mycotoxin exposure with certain illnesses have been inconclusive. Some suggest that the hazards presented by mycotoxins should be considered to be the same hazards presented by other common, non-toxic indoor molds.