When mold growth occurs in a building, occupants may begin to report both odors and a variety of health-related issues, such as headaches, difficulty breathing, skin irritation, allergic reactions, and aggravation of asthma symptoms. All of these issues may potentially be associated with mold exposure.
All molds have the potential to cause negative health effects. Molds produce allergens, irritants, and in some cases, toxins that may cause reactions in humans. The types and severity of symptoms depend, in part, on the types of mold present, the extent of an individual’s exposure, the ages of the individuals, and their existing sensitivities or allergies.
Specific reactions to mold growth can include the following:
Allergic Reactions
Inhaling or touching mold or mold spores may cause allergic reactions in sensitive individuals. Allergic reactions to mold are common; these reactions may be either immediate or delayed. Allergic responses include hay fever-type symptoms, such as sneezing, runny nose, red eyes, and skin rash (dermatitis). Mold spores and fragments can produce allergic reactions in sensitive individuals regardless of whether the mold is dead or alive. Repeated or dingle exposure to mold or mold spores may cause previously non-sensitive individuals to become sensitive. Repeated exposure has the potential to increase sensitivity.
Asthma
Molds can trigger asthma attacks in persons who are allergic (sensitized) to molds. The irritants produced by molds may also worsen asthma in non-allergic (non-sensitized) people.
Hypersensitivity Pneumonitis
Hypersensitivity pneumonitis may develop following either short-term (acute) or long-term (chronic) exposure to molds. The disease resembles bacterial pneumonia and is uncommon.
Irritant Effects
Mold exposure can cause irritation of the eyes, skin, nose, throat, and lungs, and sometimes may create a burning sensation in these areas
Opportunistic Infections
People with weakened immune systems (i.e., immune compromised or immune-suppressed individuals) may be more vulnerable to infections by molds (as well as more vulnerable than healthy persons to mold toxins). Aspergillus fumigatus, for example, has been known to infect the lungs of immune-compromised individuals. These individuals inhale the mold spores which then begin growing in their lungs. Trichoderma has also been known to infect immune-compromised children. Healthy individuals are usually not vulnerable to opportunistic infections from airborne mold exposure. However, molds can cause common skin diseases such as athlete’s foot, as well as other disorders such as yeast infections.
Mold Toxins
(Mycotoxins)
Molds can produce toxic substances called mycotoxins. Some mycotoxins cling to the surfaces of mold spores; others may be found within the spores. More than 200 mycotoxins have been identified from common molds, and many more remain to be identified. Some of the molds that are known to produce mycotoxins are commonly found in moisture-damaged buildings. Exposure pathways for mycotoxins can include inhalation, ingestion, or skin contact. Although some mycotoxins are well known to affect humans, little information is available for many others.
Aflatoxin B1 is perhaps the most well-known and studied mycotoxin. It can be produced by the molds Aspergillus flavis and Aspergillus parasiticus, and is one of the most potent carcinogens known. Ingestion of aflatoxin B1 can cause liver cancer. There is also some evidence that inhalation of aflatoxin B1 can cause lung cancer. Aflatoxin B1 has been found on contaminated grains, peanuts, and other human or animal foodstuffs. However, Aspergillus flavus and Aspergillus parasiticus are not commonly found on building materials or in indoor environments.
Much of the information on the health effects of inhalation of mycotoxins on humans comes from studies done in the workplace, along with some case studies and case reports.
Many symptoms and human health effects attributed to inhalation of mycotoxins have been reported, including: mucous membrane irritation, skin rash, nausea, immune system suppression, acute or chronic liver damage, acute or chronic central nervous system damage, endocrine effects, and cancer. More studies are needed to get a clearer picture of the health effects related to most mycotoxins. However, it is definitely prudent to avoid exposure to molds and mycotoxins.
Some molds can produce several toxins, and some molds produce mycotoxins only under certain environmental conditions. The presence of mold in a building does not necessarily mean that mycotoxins are present or that they are present in large quantities.
Note: Information on ingestion exposure, for both humans and animals, is more abundant. A wide range of health effects has been reported following ingestion of moldy foods including liver damage, nervous system damage, and immunological effects.
