Indoor Molds


Fate and Transport in the Environment

Methods for Monitoring in the Environment

Exposure Pathways

Methods for Measuring Human Exposure

Strategies for Preventing or Controlling Mold Exposure

Harmful Effects

Absorption, distribution, metabolism, and sites of toxicity


Molecular mechanism of action

Risk Assessment

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Risk assessment and risk management considerations

Risk assessment for mold is currently difficult due to limited information and research conducted on mold inhalation. Much of the toxicological data on mycotoxins is related to ingestion exposure, and extrapolation to indoor inhalation exposures introduce further uncertainties. At this time, inadequate data exists to accurately predict the risk associated with human inhalation exposure to mycotoxins in non-agricultural indoor environments.

Specific dose response for inhalation is difficult to determine and currently is limited. Hundreds of mycotoxic agents have been identified and need further study. Toxicity varies greatly among different fungi by the kinds of mycotoxins they produce and the conditions in which they are produced. The mycotoxin dose required to cause specific effect varies with the toxin, the experimental animal, and the administration route. The widely varied sensitivities among different animal species make extrapolating data to humans problematic.

People who are most likely to be affected by indoor molds include genetically sensitive individuals, infants, the elderly, and people with inflammatory lung diseases. Immune compromised individuals are susceptible to infections from indoor molds. Hospitals with immune compromised individuals, especially with cancer and HIV, are at risk. Additionally, people that have tested positive for mold allergies are at greater risk for mold related disease.

Individuals exposed to a combination of pollutants are also at greater risk for developing diseases related to indoor mold exposure. Studies have shown that exposure to a variety of airborne pollutants can increase a persons susceptibility to disease. Combustion products, tobacco smoke, and other non-biological pollutants are important. Non-biological pollutants can have the same inflammatory effect as biological agents. Both pollutants are often found in the same environment and can have an additive affect. Additionally, mold allergens, mycotoxins and b-(1Æ3)-D-glucans may have a synergistic effect on the immune system. The effect of other biological agents such as dust mites and endotoxin may also be additive.

Determining exposure scenarios and additive effects is very complex, which underscores the need to keep exposure to a minimum. This web site discusses strategies to keep mold growth limited in indoor environments in the section Strategies for Preventing or Controlling Mold Exposure. Additional information on measuring environmental mold and personal mold exposures can be found in the sections Methods for Monitoring in the Environment and Methods for Measuring Human Exposure to Molds.


California Department of Health Services. 1998. Health Effects of Toxin-Producing Indoor Molds in California. 11/21/03

Dillon, H. K., Heinsohn, P. A., Miller, J. D. (eds.). 1996. Field Guide for the Determination of Biological Contaminants in Environmental Samples. American Industrial Hygiene Association. Fairfax, VA.

Macher, J. (ed.) 1999. Bioaerosols: Assessment and control. American Conference of Governmental Industrial Hygienists. Cincinnati, OH.

National Institute of Allergy and Infectious Disease. 2000. Inappropriate Immune Responses. 11/21/03

Nelson, B. D. 2001. Stachybotrys chartarum: The Toxic Indoor Mold – APSnet. 11/23/03