Molds Inside Buildings

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Airborne Fungal Diseases
Blastomycosis
Cryptococcus
Candida
Skin Infection with Fungi
Fungal Contamination of Buildings
Allergy to Fungi
Fungi in Food

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Food and Lung Disease
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Molds Indoors

Molds need moisture to grow so that keeping materials and buildings dry is the best method of control. Filtration of incoming air and a regular program of maintenance and cleaning of ventilation ducts can reduce the levels of molds that may enter and multiply in indoor environments. Damp areas in the home such as basements and attic areas where water seepage or condensation may occur are prime growing areas for molds. Molds will reproduce quickly if the temperature and humidity conditions are right. Water damaged buildings tend to develop long term mold problems unless all structural materials and insulation are dried or replaced.

Nelson stated: "Our region experienced one of the greatest natural disasters of modern times when the Red River flooded in 1997. In Grand Forks, ND, alone, there were 9,000 flooded homes. I have been impressed with the common occurrence and extensive growth of Stachybotrys in buildings damaged by flood waters and the lack of knowledge by the general public and public and private institutions about this fungus."

Kodama and McGee found sixteen types of indoor airborne fungi. The main species belong to the families: Aspergillus, Penicillium, Cladosporium, Mucor, Stachybotrys, Absidia, Alternaria, Fusarium and Cryptostroma. The greatest health risks are Candida, Aspergillus, Histoplasma and Penicillium.

An ambitious US study assessed air from 1,717 buildings; the most common airborne fungi, both indoors and outdoors and in all seasons and regions, were Cladosporium, Penicillium, nonsporulating fungi, and Aspergillus. Stachybotrys chartarum was identified in the indoor air in 6% of the buildings studied and in the outdoor air around 1% of the buildings studied. Water distribution systems can host molds that are spread through aerosolization of fungal spores from shower heads and other faucets.

Park et al demonstrated that mold levels in dust were associated with new-onset asthma in in a damp office building. They used measures of hyhdrophilic fungi and ergosterol to assess fungal biomass. Asthma, hypersensitivity pneumonitis (HP), and sarcoidosis had been diagnosed in employees who worked in the building.

Yeasts in floor and chair dust samples increased the odds of respiratory illnesses. Rhodotorula genus of yeasts were prevalent and have been implicated in IgE-mediated allergy and HP. In bakeries, breweries, and distilleries, the yeast Saccharomyces cerevisiae is a major allergen. Other hydrophilic fungi identified were Phoma herbarum, Chaetomium globosum, Mucor plumbeus, Rhizopus stolonifer, and Stachybotrys chartarum.

They noted the limitations of fungal culture. Culture media only grow a small proportion of the viable spores and do not detect nonviable spores and fungal fragments. In contrast ergosterol found in fungal membranes is a good measure of fungal biomass that measures viable and nonviable spores and fungal fragments.

Monitoring Molds

While mold density can be measured and some mold species are identified by culture and microscopy, the significance of this data is seldom obvious. There are too many fungi in every sample to understand what is really going on. Fungal spore concentrations vary a great deal with the time of day, seasons and weather. Spore release is sporadic. Lee et al compared the performance of four bioaerosol samplers, the Reuter Centrifugal Air Sampler, the Andersen N6 single stage, the Surface Air System 90, and the Air-o-Cell, in measurements for airborne fungi in 75 public buildings. The samplers had differences in detection limits, reproducibility, and overall yield. Fungal concentrations correlated, but varied by orders of magnitude.

Air samples are cultured for mold growth; the density of mold spores is described as the number of colony forming units (CFU) per cubic meter of air. Values between 400 and 1000 in homes are common. In agricultural and industrial locations, mold density can be in the millions of CFU per cubic meter of air. For example, the concentration of airborne fungi was monitored for 6 months in a special-care unit of a hospital; 98 fungal species were identified; 48 species were potential pathogens. The average fungal density ranged from 124 to 485 CFU per cubic meter. In another hospital survey, Aspergillus fumigatus represented 77.0% of total fungal strains. Concentrations of airborne fungi showed greater variation than bacteria and ranged from 9.9-96.1 CFU per cubic meter. The concentrations of airborne microorganisms were greater in the morning compared with the afternoon.

Measurements of two fungal cell components, glucan and ergosterol, can be used to assess the “fungal load.” Foto et al reported that most airborne glucan found in damp houses was fungal in origin, coming from yeasts, intact spores, as well as hyphal and spore fragments. Correlations between airborne glucan were strong for ergosterol and visible mold. Rabine et al used liquid phase chromatography to measure ergosterol, a component of the cell membrane of microscopic fungi. They suggested that air sampling with a rotating cup collection apparatus and ergosterol measurement could be used to assess exposure to airborne fungal flora.

Hospitals

The two most prevalent fungal infections in hospitals are caused by Candida and Aspergillus species. These organisms can occur naturally in the exterior environment and enter as spores or active fungi attached to dust particles.

Toxic black mold

Stachybotyrs or “toxic black mold" is found everywhere. Half of all blood donors have antibodies to it. Evidence implicates this fungus as a problem in homes and one of the causes of the "sick building syndrome." Stachybotyrs produces macrocyclic trichothecenes, toxic compounds with a potent ability to inhibit protein synthesis and phenylspirodrimanes, immunosuppressive agents. Jarvis et al suggested that these immunosuppressive agents may be responsible for the observed high toxicity of this fungus.

Hodgson et al reported that occupants of a mold contaminated courthouse office building developed fatigue, headaches, chest tightness, mucous membrane irritation and lung disease. Stachybotyrs , Aspergillus and Penicillium species grew on interior walls; mycotoxins were identified in moldy ceiling tiles and vinyl wall coverings. Farm exposure to stachybotryotoxicosis has been reported for several decades in humans and animals. Damp hay, straw and feed grain supports fungal growth. Common symptoms in humans were skin rashes pain and inflammation in the eyes, nose mouth and throat, chest pain, cough, fever, headache, and fatigue.

Lee KS; Bartlett KH; Brauer M; Stephens GM; Black WA; Teschke KA field comparison of four samplers for enumerating fungal aerosols I. Sampling characteristics. Indoor Air. 2004; 14(5):360-6 (ISSN: 0905-6947)

Foto M; Vrijmoed LL; Miller JD; Ruest K; Lawton M; Dales REA comparison of airborne ergosterol, glucan and Air-O-Cell data in relation to physical assessments of mold damage and some other parameters. Indoor Air. 2005; 15(4):257-66 (ISSN: 0905-6947)

Jarvis, B., Sorenson, W. G., Hintikka, E., Nikulin, M., Zhou, Y., jiang, J., Wang, S., Hinkley, S., Etzel, R., and Dearborn, D. 1998. Study of toxin production by isolates of Stachybotrys chartarum and Memnoniella echinata isolated during a study of pulmonary hemosiderosis in infants. Appl. Environ. Microbiol. 64:3620-3625.

Hodgson, M. J., Morey, P., Leung, W., Morrow, L., Miller, D., Jarvis, B. B., Robbins, H., Halsey, J. F., and Storey, E. 1998. Building-associated pulomonary disease from exposure to Stachybotrys chartarum and Aspergillus versicolor. J Occup. Environ. Med. 40:241-249.

Nelson BD. Stachybotrys chartarum: The Toxic Indoor Mold. See his excellent review article online at American Phytopathologcial Society website. Accessed May 2007.Nelson is A Professor of Plant Pathology, North Dakota State University, Fargo.

Ju-Hyeong Park; Jean M. Cox-Ganser; Kathleen Kreiss; Sandra K. White; Carol Y. Rao.Hydrophilic Fungi and Ergosterol Associated with Respiratory Illness in a Water-Damaged Building. Environ Health Perspect. 2008;116(1):45-50. ©2008 National Institute of Environmental Health Sciences. Accessed online 02/12/2008.

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