There are over 119 million homes in the United States, and almost all of them experience leaks, flooding, or other forms of exposure to excessive moisture. This excessive moisture promotes mold growth, and mold spores are commonly found in dust. In recent years, “toxic mold” has attracted substantial media attention, leading to significant public concern over exposure to mold. Several studies have been performed to evaluate the health risks of human exposure to mold and mold spores. In 2009, the World Health Organization published Guidelines for Indoor Air Quality: Dampness and Mold
, which reported that exposure to mold and indoor dampness was associated with upper respiratory symptoms including chronic runny nose and cough in otherwise healthy individuals. Adverse health effects of exposure to mold can be grouped into three categories: allergic, infectious, and toxicologic.
The majority of reported health effects from household mold exposure are due to allergic and irritant reactions. Allergic upper respiratory symptoms such as runny nose, eye irritation, and cough are common after exposure. Patients with a history of asthma, eczema, and hay fever may be predisposed to a worsening of their symptoms after exposure to mold and mold spores. However, exposure to mold and mold spores has never been shown to lead to new asthma in previously healthy people. Allergic symptoms related to mold exposure are typically temporary, and resolve after removal of the mold or leaving the mold-contaminated environment.
Infectious disease from mold exposure is uncommon. In the United States there are 3 types of mold associated with infectious lung disease, but they are only present in specific geographic locations. Individuals with poor immune system function (such as patients on immune-suppressing drugs, cancer, or AIDS) may be prone to infections from common molds that typically do not cause infection in healthy individuals.
Disease due to mold toxins (formally known as respiratory mycotoxicosis) is the rarest form of mold-associated disease and does not result from household mold exposure. In the United States, this is most commonly associated with agricultural workers who are exposed to large amounts of moldy grain. The toxins produced by molds are known as trichothecenes. The common household mold species, Stachybotrys, has been shown to produce trichothecenes. However, it is unable to produce a strong enough toxin to cause symptoms in animals or humans and is only associated with the allergic symptoms described above.
Although “toxic” mold has recently become an area of concern in the media, multiple studies have found no link between household mold exposures and toxin-mediated effects. Household mold is commonly associated with allergic symptoms such as cough, runny nose, eye irritation and sinus congestion. Symptoms related to exposure to household mold should be temporary, and resolve upon removal from the moldy environment, or eradication of mold from the home.
1. WHO Guidelines for Indoor Air Quality: Dampness and Mould. Geneva: World Health Organization; 2009. Available from: http://www.ncbi.nlm.nih.gov/books/NBK143941/
2. Hodgson, M. J., Morey, P., Leung, W., Morrow, L., Miller, D., Jarvis, B. B., Robbins, H., Halsey, J. F., & Storey, E. (1998). Building-associated pulmonary disease from exposure to stachybotrys chartarum and aspergillus versicolor. Journal of Occupational and Environmental Medicine, 40, 241-248.
3. Arthur, R. "Damp Indoor Spaces and Health. Institute of Medicine: Committee on Damp Indoor Spaces and Health. The National Academy Press. ISBN 0-309-09193-4. Washington, D.C. 2004, Pp. 355." Journal of Public Health 27.2 (2005): 234. Web.