Adverse Health Effects of Indoor Mold

Concern about indoor mold growth in homes, offices and schools has increased dramatically since the media has made us aware that exposures to toxic molds can cause a variety of health effects and symptoms.

Health effects from mold exposure included allergic reactions and asthma, infections, and irritation effects including a neurologic response.

Where Molds are Found

Molds are ubiquitous and can grow on virtually any organic substance as long as moisture and oxygen are present. Molds can produce potent toxins and volatile chemicals that have the potential to affect the nervous, respiratory and immune systems. Potential health concerns are an important reason to prevent mold growth indoors and to clean up any existing indoor moisture problems that could lead to growth. However, the presence of mold does not necessarily mean that a health risk exists. For a health risk to exist there must be an exposure pathway. Contamination of an air conditioning duct system is such an exposure pathway. Mold may exist inside a wall cavity, however, and pose no human health risk if an exposure pathway is not present.

The Key to Mold Control

The key to mold control is moisture control. Sources or causes of water or moisture problems include roof leaks, localized flooding due to plumbing failures or heavy rains, slow leaks in plumbing or fixtures, and malfunction or poor design of appliances and air conditioning systems. Uncontrolled humidity can also be a source of moisture leading to mold growth, particularly in hot, humid climates. In some cases indoor mold growth may not be obvious. It is possible that mold may be growing on hidden surfaces, such as the backside of drywall, wallpaper or paneling, the top of ceiling tiles, or the underside of carpets and pads. Mold can also grow on foods, furniture, clothing, and paper products.

Health Effects of Molds

When moisture problems occur and mold growth results, building occupants may begin to report odors and a variety of health problems, such as headaches, breathing difficulties, skin irritation, allergic reactions, frequent respiratory infections, cough and aggravation of asthma symptoms.

All of these symptoms could potentially be associated with mold exposure. A moisture problem indoors not only creates a potential mold problem, but other biological microorganisms can proliferate including dust mites, bacteria, viruses, and their metabolites. Contamination of the air delivery system and damage to surfaces and indoor products like wallpaper may result. Contamination of the indoor air quality is usually the result. Allergic reactions to dusts and mold are common. Repeated exposure to allergens over time has the potential to increase allergic sensitivity in one who has become sensitized. Both dust and molds can trigger asthma attacks in persons who are sensitive to them. Also, the irritants or gasses (MVOCs—volatile organic compounds) produced by mold may also worsen asthma. The same moist environment that promotes mold growth also promotes dust mite growth and growth of other microorganisms and their byproducts including beta glucans and endotoxins.

Hypersensitivity Pneumonitis

Also called Allergic Alveolitis, this is an immune response to molds affecting the alveoli or small air sacs in the lungs; this illness may develop following either short-term or long-term exposure to molds. The disease resembles bacterial pneumonia and is very serious because it can lead to permanent lung damage. Cough, fever and shortness of breath are common symptoms. Chest x-rays and blood tests are necessary to make the diagnosis. It is estimated that less than 1% of those exposed to mold-contaminated buildings develop this problem.

Population at Risk

Chronically ill patients in hospitals may be more at risk than the general population to adverse health effects of mold exposure. Children, the elderly, and pregnant women may be more susceptible to allergic disease in general. Occupations like mold remediators are a higher risk for mold-related illnesses. People with weakened immune systems may be more vulnerable to infections by molds. Healthy individuals are usually not vulnerable to opportunistic infections from airborne mold exposure. Fungal infections are rare in healthy people. However, fungal sinusitis, once considered very rare, appears to be on the rise according to recent medical reports. This is commonly both an allergic disease and an infection where fungi colonize the sinuses. Fungi are also capable of causing skin diseases such as athletes foot, fungal skin rashes, as well as yeast infections in susceptible people with metabolic diseases (diabetes) and secondary immune problems due to overuse of antibiotics.

Health Effects of Mycotoxins

Some molds like Stachybotris are capable of producing toxic secondary metabolites called mycotoxins. Certain mycotoxins like Aflatoxin have been linked to liver damage and cancer. Mycotoxin exposure has also been linked to recurrent respiratory infections, immune disorders, and neurological symptoms. The most common symptom of mycotoxin exposure is frequent respiratory infections. Also, a variety of immune disorders may be seen. Autoimmune effects can be demonstrated affecting the myelin sheath of nerves. Mycotoxin producing molds are commonly found in severe moisture damaged buildings. Mycotoxins are considered a human health risk. We are not certain whether the neurologic symptoms seen in mold exposure patients are due to mold spore allergy, mycotoxin’s neurotoxic effects, sensitization to MVOCs, glucans, endotoxins, or a combination of these exposures. More human health studies are needed to get a clearer picture of the effects related to mycotoxins.

According to the Center for Disease Control, there are no scientific reports confirming human health effects caused by inhaled mycotoxins in the current medical literature. In fact, the dreaded mycotoxin has never been proven to cause human health effects by inhalation exposure in any peer reviewed medical journal. See ACOEM evidence-based statement: Adverse Human Effects of Molds 2002 for details.

Health Effects of MVOCs

Some primary metabolic compounds are produced by molds that are volatile and released as a gas directly into the air. These are known as microbial volatile organic compounds or MVOCs. They are also capable of combining with chemicals in products growing on walls and producing toxic chemical exposures. Because these compounds often have strong unpleasant odors, they can be the source of odors associated with mold. Exposure to volatile organic compounds has been linked to symptoms such as headaches, nasal irritation and sneezing, asthma attacks, dizziness, fatigue, nausea, odor irritation, and chemical sensitivity. If you are concerned that you may have been exposed to molds or other indoor air contaminants that are making you sick, a qualified Occupational/Environmental Physician may recommend further evaluation and testing.

Physical Examination

Tests for exposure-related health symptoms in sick patients include a thorough evaluation by a knowledgeable environmental physician. Immune studies, IGG and IGE antibody testing for molds, skin testing for dust and mold allergies, chest and sinus x-rays and CAT scans, pulmonary or breathing tests, hypersensitivity pneumonitis screening, and a nasal and sputum cultures may be indicated. A walk-through of the home, office, or school for indoor air investigation may be necessary. Air sampling may also be recommended. Treatment If a mold exposure related health problem is found, treatment may consist of removal of the individual from the contaminated environment and remediation of that environment. If multiple individuals are diagnosed with building related illness, the health department should be notified. Treatment may require moving out of a home or office until it is determined to be safe for occupancy by air quality testing. Environmental restrictions may become necessary. Allergic individuals could require allergy medications or immunotherapy. Asthmatics may need breathing medications, and infections may require special treatment. Chemically sensitive individuals usually require long-term comprehensive therapy.

Mold proliferates in damp areas. Use a dehumidifier if needed to keep the relative humidity between 30 and 60 percent.