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There are approximately 400,000 types of mold, of which less than 100,000 have been named. Approximately 1,000 types of mold are found indoors acoss America. Less than 80 molds are suspected of causing some form of illness, and only a few of them are considered toxic. Descriptions from the Glossary below are included in your test results.

Molds are organized into three groups according to human responses: Allergenic, Pathogenic and Toxigenic.

Allergenic Molds
Allergenic molds do not usually produce life-threatening health effects and are most likely to affect those who are already allergic or asthmatic. The human system responses to allergenic molds tend to be relatively mild, depending on individual sensitivities, typically producing scratchy throats, eye and nose irritations and rashes.
[For more info on Allergenic Molds scroll down or click here]

Pathogenic Molds
Pathogenic molds usually produce some type of infection. They can cause serious health effects in persons with suppressed immune systems. Healthy people can usually resist infection by these organisms regardless of dose. In some cases, high exposure may cause hypersensitivity pneumonitis (an acute response to exposure to an organism).
[For more info on Pathogenic Molds scroll down or click here]

Toxigenic Molds
Mycotoxins can cause serious health effects in almost anybody. These agents have toxic effects ranging from short-term irritation to immunosuppression and possibly cancer. Therefore, when toxigenic molds are found further evaluation is recommended.
[For more information Toxic Molds scroll down or click here]

The most common types of mold found indoors include:

  • Aspergillus and its subspecies (A. flavus, A. versicolor);
  • Cladosporium
  • Penicillium
  • Alternaria
  • Stachybotrys atra (S. atra), also known as "Black Mold."

Often, mold spores, whether dead or alive, cause adverse health effects, primarily of a respiratory nature, including hay fever-like allergic symptoms.

Many of these molds, primarily S. atra, also produce chemical toxins known as "mycotoxins," which are generated and released into the air within the mold spores, leading to the "toxic mold" designation. Exposure to these toxins can occur through inhalation, ingestion, or skin contact, and can result in symptoms including dermatitis, cough, rhinitis, nose bleeds, cold and flu symptoms, headache, general malaise and fever.

Initial awareness of adverse health effects from S. atra exposure was raised by a mid-1990's study from Cleveland, Ohio, involving infants who had died from sudden and unexplained pulmonary hemorrhage (bleeding of the lungs). Upon investigation, researchers found that the infants resided in homes with high levels of S. atra, linking S. atra exposure to serious health effects.

NOTE: When you receive your mold sample lab results from AMI, each mold found in your report will be listed along with corresponding descriptions found in this glossary.

Absidia sp - A zygomycete fungus which is considered common to the indoor environment. Reported to be allergenic. May cause mucorosis in immune compromised individuals. The sites of infection are the lung, nasal sinus, brain, eye, and skin. Infection may have multiple sites. Absidia cormbifera has been an invasive infection agent in AIDS and neutropenic patients, as well as, agents of bovine mycotic abortions, and feline subcutaneous abscesses. Acremonium species may be confused with Fusarium species that primarily produce microconidia in culture. Fusarium genera are generally much more rapid growers and produce more aerial mycelium.

Acremonium sp (Cephalosporium sp.) - Reported to be allergenic. Can produce a trichothecene toxin which is toxic if ingested. It was the primary fungus identified in at least two houses where the occupant complaints were nausea, vomiting, and diarrhea. Asexual state of Emericellopsis sp., Chaetomium sp., and Nectripsis sp. It can produce mycetomas, infections of the nails, onychomycosis, corneal ulcers, eumycotic mycetoma, endophthalmitis, meningitis, and endocarditis.

Alternaria sp - Extremely widespread and ubiquitous. Outdoors it may be isolated from samples of soil, seeds, and plants. It is commonly found in outdoor samples. It is often found in carpets, textiles, and on horizontal surfaces in building interiors. Often found on window frames. The species Alternaria alternata is capable of producing tenuazonic acid and other toxic metabolites which may be associated with disease in humans or animals. Alternaria produces large spores having sizes between 20 - 200 microns in length and 7 - 18 microns in width, suggesting that the spores from this fungi are deposited in the nose, mouth, and upper respiratory tract. It may be related to bakers asthma. It has been associated with hypersensitivity pneumoniti, sinusitis, deratomycosis, onychomycosis, subcutaneous phaeohyphomycosis, and invasive infection. Common cause of extrinsic asthma (immediate-type hypersensitivity: type I). Acute symptoms include edema and bronchiospasms, chronic cases may develop pulmonary emphysema.

Arthrinium phaeospermum- Widespread saprophyte on dead plant material, particularly swampy grasses. Should be considered an allergen. This fungus has also been documented in various subcutaneous infections. No toxic related diseases are of record to date.

Ascomycete.- One of the major classes of fungal organisms. This class contains the the"sac fungi" and yeasts. Some ascomycete spores can be identified by spore morphology, however; some care should be excersised with regard to specific identification. Many ascomycete spores are reported to be allergenic.

Aspergillus sp - A genus of fungi containing approximately 150 recognized species. Members of this genus have been recovered from a variety of habitats, but are especially common as saprophytes on decaying vegetation, soils, stored food, feed products in tropical and subtropical regions. Some species are parasitic on insects, plants and animals, including man. Species within this genus have reported Aw's (water activities) between 0.75 - 0.82. All of the species contained in this genus should be considered allergenic. Various Aspergillus species are a common cause of extrinsic asthma (immediate-type hypersensitivity: type I). Acute symptoms include edema and bronchiospasms. Chronic cases may develop pulmonary emphysema. Members of this genus are reported to cause a variety of opportunistic infections of the ears and eyes. Sever pulmonary infections may also occur. Many species produce mycotoxins which may be associated with disease in humans and other animals. Toxin production is dependent on the species or a strain within a species and on the food source for the fungus. Some of these toxins have been found to be carcinogenic in animal species. Several toxins are considered potential human carcinogens.

Aureobasidium pullulans - A cosmopolitan fungus with the main habitat apparently on the aerial parts of plants. Frequently found in moist environments. This fungus should be considered allergenic. This species has been associated with deratitis, peritonitis, pulmaonary infection, and invasive disease in AIDS patients. Probably aquired by traumatic implantation. May be recovered as a contaminant from human cutaneous sites. No toxic diseases have been documented to date.

Basidiomycetes - One of the major classes of fungal organisms. This class contains the mushrooms, shelf fungi, puffballs, and a variety of other macrofungi. It is extremely difficult to identify a specific genera of mushrooms by using standard culture plate techniques. Some basidiomycete spores can be identified by spore morphology, however; some care should be exercised with regard to specific identification. Many basidiomycete spores are reported to be allergenic.

Bipolaris sp - A widespread fungus that is most frequently associated with grasses, plant material, decaying food, and soil. It is common to both indoor and outdoor environments. Older obsolete names include Drechslera and Helminthosporium. This fungus produces large spores which would be expected to be deposited in the upper respiratory tract. Various species of this fungus can produce the mycotoxin - sterigmatocystin which has been shown to produce liver and kidney damage when ingested by laboratory animals.

Candida sp - This genus contains a variety of organisms that have been isolated from the environment, as well as human skin and mucous membranes.

Chaetomium sp. - Large ascomycetous fungus producing perithecia. It is found on a variety of substrates containing cellulose including paper and plant compost. It can be readily found on the damp or water damaged paper in sheetrock.

Chrysosporium spp - Widespread, common in the soil and on plants. Rare agents of onychomycosis, skin lesions, endocarditis, and uncommon agents of the pulmonary mycosis adiaspiromycosis. No toxic diseases have been documented to date.

Cladosporium sp. (Hormodendrum sp.) - Aw (water activity) in the range of 0.84 to 0.88. Most commonly identified outdoor fungus. The outdoor numbers are reduced in the winter. The numbers are often high in the summer. Often found indoors in numbers less than outdoor numbers. It is a common allergen. Indoor Cladosporium sp. may be different than the species identified outdoors. It is commonly found on the surface of fiberglass duct liner in the interior of supply ducts. A wide variety of plants are food sources for this fungus. It is found on dead plants, woody plants, food, straw, soil, paint and textiles. It can cause mycosis. Produces greater than 10 antigens. Antigens in commercial extracts are of variable quality and may degrade within weeks of preparation. Common cause of extrinsic asthma (immediate-type hypersensitivity: type I). Acute symptoms include edema and bronchiospasms, chronic cases may develop pulmonary emphysema.

Curvularia sp. - Reported to be allergenic. It may cause corneal infections, mycetoma and infections in immune compromised hosts.

Dreschlera sp - Conidia (spores) dimensions 40-120 x 17-28 microns. Found on grasses, grains and decaying food. It can occasionally cause a corneal infection of the eye.

Epicoccum sp. - Conidia (spores) dimensions 15-25 microns. A common allergen. It is found in plants, soil, grains, textiles, and paper products.

Fusarium sp - Aw (water activity) 0.90. A common soil fungus. It is found on a wide range of plants. It is often found in humidifiers. Several species in this genus can produce potent trichothecene toxins (5, 27). The trichothecene (scirpene) toxin targets the following systems: circulatory, alimentary, skin, and nervous. Produces vomitoxin on grains during unusually damp growing conditions. Symptoms may occur either through ingestion of contaminated grains or possibly inhalation of spores. The genera can produce hemorrhagic syndrome in humans (alimentary toxic aleukia). This is characterized by nausea, vomiting, diarrhea, dermatitis, and extensive internal bleeding. Reported to be allergenic. Frequently involved in eye, skin and nail infections.

Geotrichum sp. - Aw (water activity) 0.90. Conidia (spores) dimensions 6-12 x 3-6 microns. Aw (water activity) 0.90. A common contaminant of grains, fruits, dairy products, paper, textiles, soil and water, and often present as part of the normal human flora. The species Geotrichum candidum can cause a secondary infection (geotrichosis) in association with tuberculosis. This rare disease can cause lesions of the skin, bronchi, mouth, lung, and intestine.

Mucor sp. - Often found in soil, dead plant material, horse dung, fruits, and fruit juice. It is also found in leather, meat, dairy products, animal hair, and jute. A Zygomycetes fungus which may be allergenic (skin and bronchial tests) (7, 17). This organism and other Zygomycetes will grow rapidly on most fungal media. May cause mucorosis in immune compromised individuals. The sites of infection are the lung, nasal sinus, brain, eye, and skin. Infection may have multiple sites.

Nigrospora sp - Reported to be allergenic.

Paecilomyces sp - Commonly found in soil and dust, less frequently in air. P. variotii can cause paecilomycosis. Linked to wood-trimmers disease and humidifier associated illnesses. They are reported to allergenic. Some members of this genus are reported to cause pneumonia. It may produce arsine gas if growing on arsenic substrate. This can occur on wallpapers covered with paris green.

Papulospora sp. - This fungi is found in soil, textiles, decaying plants, manure, and paper.

Penicillium sp - Aw (water activity) 0.78 - 0.88. A wide number of organisms have placed in this genera. Identification to species is difficult. Often found in aerosol samples. Commonly found in soil, food, cellulose, and grains (17, 5). It is also found in paint and compost piles. It may cause hypersensitivity pneumonitis and allergic alveolitis in susceptible individuals. It is reported to be allergenic (skin) (7, 17). It is commonly found in carpet, wallpaper, and in interior fiberglass duct insulation (NC). Some species can produce mycotoxins. Common cause of extrinsic asthma (immediate-type hypersensitivity: type I). Acute symptoms include edema and bronchiospasms, chronic cases may develop pulmonary emphysema.

Periconia sp - No information available, more to come.

Phoma sp. - A common indoor air allergen. It is similar to the early stages of growth of Chaetomium sp. The species are isolated from soil and associated plants (particularly potatoes). Produces pink and purple spots on painted walls (3, 17). It may have antigens which cross-react with those of Alternaria sp. It will grow on butter, paint, cement, and rubber. It may cause phaeohyphomycosis, a systematic or subcutaneous disease.

Pithomyces sp. - Grows on dead grass in pastures. Causes facial eczema in ruminants.

Rhizomucor sp. - The Zygomycetous fungus is reported to be allergenic. It may cause mucorosis in immune compromised individuals. It occupies a biological niche similar to Mucor sp. It is often linked to occupational allergy. The sites of infection are the lung, nasal sinus, brain, eye, and skin. Infection may have multiple sites.

Rhizopus sp - The Zygomycetous fungus is reported to be allergenic. It may cause mucorosis in immune compromised individuals. It occupies a biological niche similar to Mucor sp. It is often linked to occupational allergy. The sites of infection are the lung, nasal sinus, brain, eye, and skin. Infection may have multiple sites.

Rhodotorula sp - A reddish yeast typically found in moist environments such as carpeting, cooling coils, and drain pans. In some countries it is the most common yeast genus identified in indoor air. This yeast has been reported to be allergenic. Positive skin tests have been reported. It has colonized in terminally ill patients. Sporotrichum sp - Reported to be allergenic. See also Sporothrix sp. as there is some taxonomic confusion between these two genera. This genera does not cause sporotrichosis.

Stachybotrys sp. - Aw (water activity) - 0.94, optimum Aw (water activity) - >0.98. Several strains of this fungus (S. atra, S. chartarum and S. alternans are synonymous) may produce a trichothecene mycotoxin- Satratoxin H - which is poisonous by inhalation. The toxins are present on the fungal spores. This is a slow growing fungus on media. It does not compete well with other rapidly growing fungi. The dark colored fungi grows on building material with a high cellulose content and a low nitrogen content. Areas with relative humidity above 55% and are subject to temperature fluctuations are ideal for toxin production. Individuals with chronic exposure to the toxin produced by this fungus reported cold and flu symptoms, sore throats, diarrhea, headaches, fatigue, dermatitis, intermittent local hair loss, and generalized malaise. The toxins produced by this fungus will suppress the immune system affecting the lymphoid tissue and the bone marrow. Animals injected with the toxin from this fungus exhibited the following symptoms: necrosis and hemorrhage within the brain, thymus, spleen, intestine, lung, heart, lymph node, liver, and kidney. The mycotoxin is also reported to be a liver and kidney carcinogen. Affects by absorption of the toxin in the human lung are known as pneumomycosis. This organism is rarely found in outdoor samples. It is usually difficult to find in indoor air samples unless it is physically disturbed. The spores are in a gelatinous mass. Appropriate media for the growth of this organism will have a high cellulose content and a low nitrogen content. The spores will die readily after release. The dead spores are still allergenic and toxigenic. Percutaneous absorption has caused mild symptoms.

Stemphylium sp. - Reported to be allergenic. Isolated from dead plants and cellulose materials.

Syncephalastrum sp. - Can cause a respiratory infection characterized by a solid fungal ball.

Trichoderma sp - It is commonly found in soil, dead trees, pine needles, paper, and unglazed ceramics. It often will grow on other fungi. It produces antibiotics which are toxic to humans. It has been reported to be allergenic (7, 17). It readily degrades cellulose.

Trichophyton sp - Can cause ring worm, athlete's foot, skin, nail, beard, and scalp (5, 6). Reported to be allergenic. Found on soil and skin.

Ulocladium sp - Has an Aw (water activity) of 0.89. Isolated from dead plants and cellulose materials. Found on textiles.

Verticillium sp - Conidia (spores) dimensions 2.3-10 x 1-2.6 microns. Found in decaying vegetation, on straw, soil, and arthropods. A rare cause of corneal infections.

Wallemia sp - Has an Aw (water activity) of 0.75. Conidia (spores) dimensions 2.5-3.5 microns. Found in sugary foods, salted meats, dairy products, textiles, soil, hay, and fruits.

Yeast - Various yeasts are commonly identified on air samples. Some yeasts are reported to be allergenic. They may cause problems if a person has had previous exposure and developed hypersensitivity. Yeasts may be allergenic to susceptible individuals when present in sufficient concentrations.

More on Allergenic Molds
Along with pollens from trees, grasses, and weeds, molds are an important cause of seasonal allergic rhinitis. People allergic to molds may have symptoms from spring to late fall. The mold season often peaks from July to late summer. Unlike pollens, molds may persist after the first killing frost. Some can grow at subfreezing temperatures, but most become dormant. Snow cover lowers the outdoor mold count dramatically but does not kill molds. After the spring thaw, molds thrive on the vegetation that has been killed by the winter cold.

In the warmest areas of the United States, however, molds thrive all year and can cause year-round (perennial) allergic problems. In addition, molds growing indoors can cause perennial allergic rhinitis even in the coldest climates.

When inhaled, microscopic fungal spores or, sometimes, fragments of fungi may cause allergic rhinitis. Because they are so small, mold spores may evade the protective mechanisms of the nose and upper respiratory tract to reach the lungs.

In a small number of people, symptoms of mold allergy may be brought on or worsened by eating certain foods, such as cheeses, processed with fungi. Occasionally, mushrooms, dried fruits, and foods containing yeast, soy sauce, or vinegar will produce allergic symptoms. There is no known relationship, however, between a respiratory allergy to the mold Penicillium and an allergy to the drug penicillin, made from the mold.

Which molds are allergenic?
Like pollens, mold spores are important airborne allergens only if they are abundant, easily carried by air currents, and allergenic in their chemical makeup. Found almost everywhere, mold spores in some areas are so numerous they often outnumber the pollens in the air. Fortunately, however, only a few dozen different types are significant allergens.

In general, Alternaria and Cladosporium (Hormodendrum) are the molds most commonly found both indoors and outdoors throughout the United States. Aspergillus, Penicillium, Helminthosporium, Epicoccum, Fusarium, Mucor, Rhizopus, and Aureobasidium (Pullularia) are also common.

Mold counts
Similar to pollen counts, mold counts may suggest the types and relative quantities of fungi present at a certain time and place. For several reasons, however, these counts probably cannot be used as a constant guide for daily activities. One reason is that the number and types of spores actually present in the mold count may have changed considerably in 24 hours because weather and spore dispersal are directly related. Many of the common allergenic molds are of the dry spore type--they release their spores during dry, windy weather. Other fungi need high humidity, fog, or dew to release their spores. Although rain washes many larger spores out of the air, it also causes some smaller spores to be shot into the air.

In addition to the effect of day-to-day weather changes on mold counts, spore populations may also differ between day and night. Day favors dispersal by dry spore types and night favors wet spore types.

Other mold-related disorders
Fungi or microorganisms related to them may cause other health problems similar to allergic diseases. Some kinds of Aspergillus may cause several different illnesses, including both infections and allergy. These fungi may lodge in the airways or a distant part of the lung and grow until they form a compact sphere known as a "fungus ball." In people with lung damage or serious underlying illnesses, Aspergillus may grasp the opportunity to invade the lungs or the whole body.

In some individuals, exposure to these fungi also can lead to asthma or to a lung disease resembling severe inflammatory asthma called allergic bronchopulmonary aspergillosis. This latter condition, which occurs only in a minority of people with asthma, is characterized by wheezing, low-grade fever, and coughing up of brown-flecked masses or mucus plugs. Skin testing, blood tests, X-rays, and examination of the sputum for fungi can help establish the diagnosis. Corticosteroid drugs are usually effective in treating this reaction; immunotherapy (allergy shots) is not helpful.


More On Pathogenic Molds
Pathogenic molds usually produce some type of infection. The word pathogenic literally means, "capable of causing disease". A normal, healthy individual can probably resist infection by these organisms regardless of dose, however, pathogenic molds can cause serious health effects in persons with suppressed, underdeveloped, or compromised immune systems. In some cases, high exposure may cause hypersensitivity pneumonitis (an acute response to exposure to an organism). People with compromised immune systems would be, infants and small children whose immune systems are not fully developed, elderly people whose immune systems are essentially worn out, and anyone exposed to AIDS, chemotherapy, pneumonia, bronchitis, and other respiratory infections.

Bipolaris Species
The U.S. Government's Occupational Safety and Health Administration [OSHA] lists the following as the health effects of Bipolaris mold: Allergen, Irritant, Hypersensitivity pneumonitis, Dermatitis.

Bipolaris australiensis showing sympodial development of pale brown, fusiform to ellipsoidal, pseudoseptate, poroconidia on a geniculate or zig-zag rachis.

Colonies are moderately fast growing, effuse, grey to blackish brown, suede-like to floccose with a black reverse. Microscopic morphology shows sympodial development of pale brown pigmented, pseudoseptate conidia on a geniculate or zig-zag rachis. Conidia are produced through pores in the conidiophore wall (poroconidia) and are straight, fusiform to ellipsoidal, rounded at both ends, smooth to finely roughened and germinating only from the ends (bipolar).

Description and Natural Habitats
Bipolaris is a dematiaceous, filamentous fungus. It is cosmopolitan in nature and is isolated from plant debris and soil. The pathogenic species have known teleomorphic states in the genus Cochliobolus and produce ascospores.

The genus Bipolaris contains several species. Among these, three well-known pathogenic species are Bipolaris spicifera, Bipolaris australiensis, and Bipolaris hawaiiensis. The genus Bipolaris contains about 45 species which are mostly subtropical and tropical plant parasites. However, several species notably B. australiensis, B. hawaiiensis and B. spicifera, are well documented human pathogens. Clinical manifestations include mycotic keratitis, subcutaneous phaeohyphomycosis, sinusitis, peritonitis in patients on continuous ambulatory peritoneal dialysis (CAPD), and cerebral and disseminated infections.

Pathogenicity and Clinical Significance
Bipolaris is one of the causative agents of phaeohyphomycosis. The clinical spectrum is diverse, including allergic and chronic invasive sinusitis, keratitis, endophthalmitis, endocarditis, endarteritis, osteomyelitis, meningoencephalitis, peritonitis, otitis media (in agricultural field workers),and fungemia as well as cutaneous and pulmonary infections and allergic bronchopulmonary disease. Bipolaris can infect both immunocompetent and immunocompromised host.

As well as being isolated as saprophytes on plants, Bipolaris may be pathogenic to certain plant species, particularly to Graminiae and also to animals, such as the dog. It may cause nasal mycotic granuloma in the cattle. Bipolaris may also be isolated as a laboratory contaminant.

Macroscopic Features
Bipolaris colonies grow rapidly, reaching a diameter of 3 to 9 cm following incubation at 25°C for 7 days on potato dextrose agar. The colony becomes mature within 5 days. The texture is velvety to woolly. The surface of the colony is initially white to grayish brown and becomes olive green to black with a raised grayish periphery as it matures. The reverse is also darkly pigmented and olive to black in color.

Microscopic Features
The hyphae are septate and brown. Conidiophores (4.5-6 µm wide) are brown, simple or branched, geniculate and sympodial, bending at the points where each conidium arises from. This property leads to the zigzag appearance of the conidiophore. The conidia, which are also called poroconidia, are 3- to 6-celled, fusoid to cylindrical in shape, light to dark brown in color and have sympodial geniculate growth pattern. The poroconidium (30-35 µm x 11-13.5 µm) is distoseptate and has a scarcely protuberant, darkly pigmented hilum. This basal scar indicates the point of attachment to the conidiophore. From the terminal cell of the conidium, germ tubes may develop and elongate in the direction of longitudinal axis of the conidium.

Teleomorph production of Bipolaris is heterothallic. The perithecium is black in color, and round to ellipsoidal in shape. The ascospores are flagelliform or filiform, hyaline in nature and are found in clavate-shaped or cylindrical asci. Each ascus contains eight ascospores.

Laboratory Precautions
No special precautions other than general laboratory precautions are required.

In vitro susceptibility testing procedures have not been standardized for dematiaceous fungi yet. Very limited data are available on susceptibility of Bipolaris. These data suggest that itraconazole MICs are variable and voriconazole MICs are considerably low.

Amphotericin B and ketoconazole are used in treatment of Bipolaris infections. Surgical debridement may be indicated in some cases, such as sinusitis.


More On Toxic Molds
"Black Mold" is a term commonly used to describe molds that are black and slimy. It is also often used in reference to toxic mold; molds that are know to present health risks to humans and animals by producing Mycotoxins (poisons). Mycotoxins are fungal metabolites that have been identified as toxic agents.

It should be noted, however, that not all black mold is toxic and that not all toxic mold is black. In fact, there are over 400,000 different types of mold and many of them are black in color of which only a portion have been identified. Black mold and/or toxic mold are terms often used in reference to Stachybotrys, (stack-ee-bot-ris) aka: Stachybotrys chartarum, aka: Stachybotrys atra.

Many fungi (e.g., species of Aspergillus, Penicillium, Fusarium, Trichoderma, and Memnoniella) in addition to Stachybotrys can produce potent mycotoxins, some of which are identical to compounds produced by Stachybotrys. For this reason, Stachybotrys cannot be treated as uniquely toxic in indoor environments.

Virtually everyone has some type of mold or another somewhere in their home. Although not all types are toxic, it is sometimes difficult to distinguish types without lab testing. Black molds can develop from water seepage, and while toxic mold is less common than other mold species, it is not rare. For that reason, it is imperative to treat and remove all molds as if they are potentially harmful. Regardless of the type of mold found, a home containing mold is not essentially a healthy home.

The notoriety of Stachybotrys leads some to believe that is the only “toxic mold”. That is not true. A number of toxigenic molds have been found during indoor air quality investigations in different parts of the world. Among the genera most frequently found in numbers exceeding levels that they reach outdoors are Aspergillus, Penicillium, Stachybotrys, and Cladosporium (Burge, 1986; Smith et al., 1992; Hirsh and Sosman, 1976; Verhoeff et al., 1992; Miller et al., 1988; Gravesen et al., 1999). Penicillium, Aspergillus and Stachybotrys toxicity, especially as it relates to indoor exposures, are discussed briefly in the paragraphs that follow.

Penicillium species have been shown to be fairly common indoors, even in clean environments, but can be problematic when indoor spore levels are higher than outdoors (Burge, 1986; Miller et al., 1988; Flannigan and Miller, 1994). Spores have the highest concentrations of mycotoxins, although the vegetative portion of the mold, the mycelium, can also contain the poison. The viability of spores is not essential to toxicity. In other words, a dead spore can still be a source of toxin.

Aspergillus species are also fairly prevalent in problem buildings. This genus contains several toxigenic species, among which the most important are, A. parasiticus, A. flavus, and A. fumigatus. Aflatoxins produced by the first two species are among the most extensively studied mycotoxins. They are among the most toxic substances known, being acutely toxic to the liver, brain, kidneys and heart, and with chronic exposure, potent carcinogens of the liver. They are also teratogenic (Smith and Moss, 1985; Burge, 1986). Symptoms of acute aflatoxicosis are fever, vomiting, coma and convulsions (Smith and Moss, 1985). A. flavus is found indoors in tropical and subtropical regions, and occasionally in specific environments such as flowerpots. A. fumigatus has been found in many indoor samples. A more common aspergillus species found in wet buildings is A. versicolor, where it has been found growing on wallpaper, wooden floors, fibreboard and other building material. A. versicolor does not produce aflatoxins, but does produce a less potent toxin, sterigmatocystin, an aflatoxin precursor (Gravesen et al., 1994). While symptoms of aflatoxin exposure through ingestion are well described, symptoms of exposure such as might occur in most moderately contaminated buildings are not know, but are undoubtedly less severe due to reduced exposure. However, the potent toxicity of these agents advise that prudent prevention of exposures are warranted when levels of aspergilli indoors exceed outdoor levels by any significant amount. A. fumigatus has been found in many indoor samples. This mold is more often associated with the infectious disease aspergillosis, but this species does produce poisons for which only crude toxicity tests have been done (Betina, 1989). Recent work has found a number of tremorgenic toxins in the conidia of this species (Land et al., 1994). A. ochraceus produces ochratoxins (also produced by some penicillia as mentioned above). Ochratoxins damage the kidney and are carcinogenic (Smith and Moss, 1985).

Stachybotrys chartarum (atra) has been much discussed in the popular press and has been the subject of a number of building related illness investigations. It is a mold that is not readily measured from air samples because its spores, when wet, are sticky and not easily aerosolized. Because it does not compete well with other molds or bacteria, it is easily overgrown in a sample, especially since it does not grow well on standard media (Jarvis, 1990). Its inability to compete may also result in its being killed off by other organisms in the sample mixture. Thus, even if it is physically captured, it will not be viable and will not be identified in a cultured sample media, even though it is present in the environment and those who breathe it can have toxic exposures. For that reason, it is prudent to take a surface sample, such as tape or bulk, whenever evidence of black mold is found. This organism has a high moisture requirement, so it grows vigorously where moisture has accumulated from roof or wall leaks, or chronically wet areas from plumbing leaks. It is often hidden within the building envelope and inside wall cavities. When Stachybotrys is found in an air sample, it should be searched out in walls or other hidden spaces, where it is likely to be growing in abundance. This mold has a very low nitrogen requirement, and can grow on wet hay and straw, paper, wallpaper, ceiling tiles, carpets, insulation material (especially cellulose-based insulation).

This information was quoted from an article called “Is Indoor Mold Contamination a Threat to Health?” by Harriet M. Ammann, Ph.D., D.A.B.T. - Senior Toxicologist at Washington State Department of Health, Olympia, Washington.
For a full copy of her report in PDF format CLICK HERE
For a full copy of her report in Microsoft Word format CLICK HERE

Stachybotrys is a specific family (genus) of mold that is present in the environment. Out-of-doors stachybotrys molds help to decay organic matter. 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 a 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.

Like many other molds, stachybotrys can spread both through the generation of spores and the growth of root-like structures 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 this danger of the airborne dispersion of spores, all cleaning and removal of stachybotrys mold should be done using appropriate controls.

Stachybotrys has a high moisture requirement, so it grows vigorously where moisture has accumulated from roof or wall leaks, or chronically wet areas from plumbing leaks. It is often hidden within the building envelope. When S. chartarum is found in an air sample, it should be searched out in walls or other hidden spaces, where it is likely to be growing in abundance. This mold has a very low nitrogen requirement, and can grow on wet hay and straw, paper, wallpaper, ceiling tiles, carpets, insulation material (especially cellulose-based insulation). It also grows well when wet filter paper is used as a capturing medium.

S. chartarum has a well-known history in Russia and the Ukraine, where it has killed thousands of horses, which seem to be especially susceptible to its toxins. These toxins are macrocyclic trichothecenes. They cause lesions of the skin and gastrointestinal tract, and interfere with blood cell formation. (Sorenson, 1993). Persons handling material heavily contaminated with this mold describe symptoms of cough, rhinitis, burning sensations of the mouth and nasal passages and cutaneous irritation at the point of contact, especially in areas of heavy perspiration, such as the armpits or the scrotum (Andrassy et al., 1979).

One case study of toxicosis associated with macrocyclic trichothecenes produced by S. chartarum in an indoor exposure, has been published (Croft et al., 1986), and has proven seminal in further investigations for toxic effects from molds found indoors. In this exposure of a family in a home with water damage from a leaky roof, complaints included (variably among family members and a maid) headaches, sore throats, hair loss, flu symptoms, diarrhea, fatigue, dermatitis, general malaise, psychological depression. (Croft et al, 1986; Jarvis, 1995).

Stachybotrys has a different make up than most other molds and does not produce airborne spore as easily as other molds. If you were to physically touch a spot of black mold, it would feel slimy and would smear on the area. Areas and substances where black mold can be found include water soaked wood, ceiling tiles, wall paneling, cardboard, even items made of cotton. Black mold can grow on drywall and insulation and can infest areas in the floors, walls and ceilings.
Moisture is essential to the growth of black mold, and when it is wet it is shiny in appearance.

If and when you are contemplating clean up of black mold, there are two important considerations:

1. Know what you are dealing with.
If you were told you have an animal in your house, your first question would be, “What kind of animal?” Based on the answer, you will know the best way to “suit up” for the encounter. If you know you have a kitty-cat, you may need a pair of gloves to keep from getting scratched. If you know you have a lion, you might want a whip, a chair, and a pistol just in case. Same with mold. If you are going to clean up some common allergenic molds you will need a cheap dust mask and a pair of rubber gloves. If you are going to clean up toxic mold, you will need an expensive respirator and other protective gear. Perhaps you will want to set up a containment area to keep toxic mold spores from contaminating other areas of your home. Taping off vents and duct work can help prevent the spread of toxic spores into the HVAC system as well.

2. Verify the extent of the problem.
Many of the indoor mold problems you will encounter are the direct result of water intrusion, i.e. improper drainage and irrigation, plumbing leaks, rain and condensation issues. After discovering the root of the problem and correcting it, you may be able to clean the area with bleach depending on the scope of the contamination. In the even you choose to do the clean up yourself, it is important to understand that bleach is only good for cleaning mold off of a surface. It should not be used for cleaning mold that is deeply embedded. Bleach dries too quickly to penetrate deep enough into wood or drywall to reach embedded mold, therefore, it does not always reach mold that is embedded beyond the surface. For that reason, after or instead of cleaning with bleach, use a mildewcide (not a fungicide) disinfect cleaner to penetrate deep into contaminated construction materials to kill embedded mold. After this you must take care to thoroughly dry the cleaned area. If there is any trace of mold left behind, it is only a matter of time before you will repeating the entire process. One way to be sure your clean up is effective is to have the cleaned materials re-tested by your inspector.

For more information on cleaning mold CLICK HERE.

3. Hiring a Contractor
If you choose to have a contractor clean up the contamination, there are a couple of important matters for you to consider:

a) Only hire experience Mold Remediation Contractors. There are many fine and well established remodeling companies around who do great remodeling work but are not well experienced in mold remediation. Remodeling contractors who are not remediation specialist can make a bad situation absolutely horrible with their lack of mold experience.

b) Insist on references of customers who's jobs are at least one year old. A mold clean up job can look really great right after its finished. But if it isn't done correctly the problem can come back much worse than before within six months to a year.

c) Never allow your contractor to conduct his own post-remediation clearance testing.




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