Molds

Molds are a group of multicellular fungi, which like other fungi, survive by breaking down organic matter. They are composed of networks of filaments called hyphae and reproductive tissues called spores. Molds are a ubiquitous and necessary part of almost every environment and ecosystem and, therefore, exposure to molds or their spores is virtually unavoidable. Molds are known to cause a specific set of well-documented diseases in humans, which will be described below. Molds cause disease by way of three specific mechanisms: (1) by causing an allergic immune response; (2) by the toxic effects of certain mold by-products; and (3) by direct infection. This article will focus primarily on the noninfectious health effects of molds.

Recently, molds have also been associated with a wide variety of diseases and disabilities resulting from allegedly contaminated indoor environments. While there is little objective evidence of these claims in the scientific or medical literature, this controversy remains a topic of heated discussion in the media and the courtroom.

It has been estimated that 10 percent of the U.S. population has allergic (immunoglobulin E [IgE]) antibodies to common outdoor molds. This means that they have been exposed to and have reacted to mold antigens (allergy-causing particles). It is estimated that up to half of these individuals have experienced symptoms related to mold exposure during their lifetimes. The most common manifestations of mold allergy sensitivity are asthma and allergic rhinitis. The symptoms of asthma include shortness or breath and decreased exercise tolerance, whereas the symptoms of allergic rhinitis include sneezing, and stuffy, runny nose.

The relationship between the severity of asthma, particularly in children, and outdoor mold is well established. Indoor molds have also been studied as a cause of worsening asthma symptoms, but here, the evidence is less convincing because damp and unclean indoor environments are likely to contain a variety of other allergens as well.

Allergic rhinitis and dermatitis (a similar process of inflammation of the skin) have been shown to be related to mold allergens, but much less so than pollens, animal dander, and house dust mites. Severe immune reactions to molds can occur and may present as a syndrome called hypersensitivity pneumonitis. This condition is usually due to inhaling large quantities of mold or other foreign proteins as a result of occupational exposures. Two other syndromes, allergic bronchopulmonary aspergillosis (ABPA) and allergic fungal sinusitis (AFS) are very rare, and occur when individuals who are allergic to molds have fungi growing inside cavities in their lungs or sinuses. The role of molds in chronic sinusitis is controversial because molds are found in the nasal cavities of healthy individuals as well as those with chronic sinus problems.

People with asthma or other allergic conditions should consider minimizing their exposure to indoor and outdoor irritants and allergens, including molds. Measurement of antibodies to molds is not routinely done and cannot establish a causative or temporal relationship with particular exposures.