The Roof Cleaners

Don't Panic!

Most of us have immune systems that are fully capable of resisting the effects of fungi described below. As a result it would be highly unlikely for any of us to suffer any of the ill effects described. But if fungal colonies are allowed to persist and multiply then the high concentrations of the molds and their volatile organic chemical metabolites might be sufficient to increase the risks from our exposure to them.

Stachybotrys chartarum (atra) molds can thrive on water damaged, cellulose-rich material in buildings such as sheet rock, paper, ceiling tiles, insulation backing, wallpaper, etc. In the majority of cases where Stachybotrys is found indoors, water damage has gone unnoticed or ignored since it requires extended periods of time with increased levels of moisture for growth to occur. Stachybotrys is usually black and slimy in appearance. Events of water intrusion that are not addressed quickly tends to support the growth of more xerophilic fungi such as Pencillium and Aspergillus.

Stachybotrys is another fungi that has the ability to produce mycotoxins, ones that are toxic and can be immunosuppressive. Exposure to these mycotoxins can result through inhalation, ingestion, and dermal exposure. Symptoms of exposure include dermatitis, cough, rhinitis, nose bleeds, cold and flu-like symptoms, headache, general malaise, and fever.

The Cladosporium genera of mold are pigmented dark green to black in the front, and black on the reverse with a velvety to powdery texture.  One of the most commonly isolated from indoor and outdoor air, Cladosporium spp. are found on decaying plants, woody plants, food, straw, soil, paint, textiles, and the surface of fiberglass duct liner in the interior of supply ducts.

There are over 30 species in the Cladosporium genus. The most common are C. elatum, C. herbarum, C. sphaerospermum, and C. cladosporioides. These fungi are the causative agents of skin lesions, keratitis, nail fungus, sinusitis, asthma, and pulmonary infections.  Acute symptoms of exposure to Cladosporium are edema and bronchiospasm, and chronic exposure may lead to pulmonary emphysema.

Aspergillus is the most common genus of fungi in our environment (it especially likes to grow on corn plants) with more than 160 different species of mold. Sixteen of these species have been documented as causing human disease. Aspergillosis is now the 2nd most common fungal infection requiring hospitalization in the United States.

Aspergillus fumigatus. The most encountered species causing infection. It is seen abundantly in decomposing organic material, such as self-heating compost piles, since it readily grows at temperatures up to 55 C. People who handle contaminated material often develop hypersensitivity to the spores of Aspergillus and may suffer severe allergic reactions upon exposure.

Aspergillus flavus. The 2nd most encountered fungi in cases of Aspergillus infection. It is also known to produce the mycotoxin aflatoxin, one of the most potent carcinogens known to man. In the 1960s, 100,000 turkey poults in Great Britain died from ingesting contaminated feed. Most countries have established levels for aflatoxin in food. However, the risks associated with airborne exposure are not adequately studied and no exposure standards exist.

Aspergillus niger. The 3rd most common Aspergillus fungi associated with disease and the most common of any Aspergillus species in nature due to its ability to grow on a wide variety of substrates. This species may cause a "fungal ball", which is a condition where the fungus actively proliferates in the human lung, forming a ball. It does so without invading the lung tissue.

Fusarium spp.,common soil fungus and inhabitant on a wide array of plants, this fungi is often found in humidifiers and has been isolated from water-damaged carpets and a variety of other building materials.  Human exposure may occur through ingestion of contaminated grains and possibly through the inhalation of spores. Fusarium spp. is frequently involved with eye, skin, and nail infections.

Several species can produce the trichothecene toxins which target the circulatory, alimentary, skin, and nervous systems. Vomitoxin is one such tricothecene mycotoxin that has been associated with outbreaks of acute gastrointestinal illness in humans. Zearalenone is another mycotoxin produced by Fusarium. It is similar in structure to the female sex hormone estrogen and targets the reproductive organs.

Penicillium fungi are commonly found in soil, food, cellulose, grains, paint, carpet, wallpaper, interior fiberglass duct insulation, and decaying vegetation. Penicillium may cause hypersensitivity pneumonitis, asthma, and allergic alveolitis in susceptible individuals.

The genus Penicillium has several species. The most common ones include Penicillium chrysogenum, Penicillium citrinum, Penicillium janthinellum, Penicillium marneffei, and Penicillium purpurogenum.

These fungi have been isolated from patients with keratitis, ear infections, pneumonia, endocarditis, peritonitis, and urinary tract infections. Penicillium infections are most commonly exhibited in immunosuppressed individuals.

In conclusion, during the digestion of substrates, fungi secrete enzymes into nutrients in order to break down complex compounds into simpler compounds that can be taken up by the fungi and used as nutrition.  These digested nutrients produce secondary metabolic byproducts called mycotoxins that are released to give the fungi a competitive edge over other microorganisms and fungi. Unfortunately, mycotoxins can also be toxic to humans causing a variety of responses including cold/flu-like symptoms, sore throats, headaches, nose bleeds, fatigue, diarrhea, dermatitis, and immune suppression. Some mycotoxins may also be carcinogenic and teratogenic. Molds that have been known to potentially produce these toxins are Acremonium, Alternaria, Aspergillus, Chaetomium, Cladosporium, Fusarium, Penicillium, and Stachybotrys.

Even though these molds may potentially produce mycotoxins, they will not do so unless specific environmental conditions exist.  Currently, it is unknown exactly what conditions promote the growth of mycotoxin production and more scientific research needs to be conducted on this topic for it to be fully understood.