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Black Deadly / Toxic Mold:

Stachybotrys is a type of mold that has jumped into the public consciousness during the past few years. This awareness has been driven by media stories, legal cases, medical research, and a growing body of anecdotal stories. Stachybotrys is a specific family (genus) of mold that is present in the environment. Out-of-doors Stachybotrys molds help to decay organic matter. 

stachybotrys mold spores

One particular species known as Stachybotrys atra (sometimes known as Stachybotrys chartarum) is prone to growth indoors. This mold is normally dark brown or black in color. It can look slimy, sooty, or even like grayish white strands, depending on the amount of moisture available and the length of time it has been growing. It is important to remember that many other common indoor molds can look similar to Stachybotrys (including Cladosporium, Aspergillus, Alternaria, and Drechslera), so testing is critical to conclusively identify Stachybotrys in a building.

Stachybotrys mold needs the proper conditions in order to grow, including moisture, a nutrient source, temperature, and time. Standing water or a relative humidity of 90% or higher is necessary for Stachybotrys to start germination and grow. However, once the Stachybotrys begins to grow it can continue to propagate even if the surface water source dries up and the relative humidity falls to 70%. The nutrient sources that best support Stachybotrys are those with high cellulose content. As such, Stachybotrys thrives on natural materials such as hay, straw, and wood chips, as well as building materials such as ceiling tile, drywall, paper vapor barriers, wallpaper, insulation backing, cardboard boxes, and paper files. Stachybotrys survives a wide variation in temperature and grows most proficiently in temperatures that humans consider warm to moderately hot. It tends to develop more slowly than many other molds�one to two weeks after moisture intrusion, as compared to one to two days for molds like Aspergillus, Penicillium, or Cladosporium. Despite its slow start, Stachybotrys usually develops into the dominant mold if the conditions are favorable, eventually crowding out other mold types that may have colonized the material first. It is often found in conjunction with, or is preceded by, Chaetomium.

Like many other molds, Stachybotrys can spread both through the generation of spores and the growth of root-like tendrils called mycelia. Stachybotrys spores grow in clusters at the end of stem-like structures known as hyphae. The spores do not easily disperse into the air if the colonized material is wet, as the spores are held together by a sticky/slimy coating. Distribution through the air is possible when the mold dries out or is disturbed. Because of the danger of airborne dispersion of spores, all cleaning and removal of Stachybotrys mold should be done using appropriate controls.

stachybotrys contamination

Health Effects:

In general, exposure to mold spores and pieces can result in allergic reactions, infections, or toxic (poisonous) effects. These health effects are the result of exposure by skin contact, ingestion, or breathing the mold. Stachybotrys has been studied for a number of years, with most of the early studies done on animals. Stachybotrys exposure is linked to allergic reactions. People in buildings with active Stachybotrys growth generally experience symptoms that include irritation and watering of the eyes and nose. Coughing and skin irritation are also allergic reactions commonly associated with Stachybotrys exposure.

Animal studies clearly show that Stachybotrys exposure, even at low levels, suppresses the immune system. Anecdotal data clearly supports this immuno-suppressive capability in humans. As such, exposed individuals are often susceptible to bacterial and viral infections such as the flu. The reason Stachybotrys is of such concern is that medical evidence has proven that this mold has toxic properties. Stachybotrys produces a mycotoxin (i.e., poison from a fungus) named trichothecenes.

mold allergy and symptoms

When inhaled or ingested Stachybotrys can cause:

  • Sore/hoarse throat

  • Cold and flu symptoms (headaches, slight fever, and muscle aches)

  • Nosebleeds

  • Tingling or burning of nose, mouth, and perspiration areas (under the arms or between the legs)

  • Chronic fatigue

  • Dizziness

  • Nausea/vomiting

  • Memory loss

  • Attention deficit/concentration problems

  • Personality changes such as irritability or depression

  • Neurological disorders such as tremors

  • Hair loss

  • Coughing with blood

  • Bleeding in the lungs (hemosiderosis)

  • Damage to internal organs including blood, liver, kidneys, and lungs


The symptoms and health effects related to Stachybotrys depend on an individual's pre-existing health situation, length of exposure, and the amount of Stachybotrys in the environment. It has also been shown that the level of mycotoxins produced by Stachybotrys mold varies over time and depends on the environmental conditions present at the growth site. Because of this, different people in the same situation, even family members, may experience different sets and severity of symptoms. Information by, Michael A. Pinto, CSP, CMP, is CEO of Wonder Makers Environmental, Inc.,

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