Why Is Mold A Health Concern?
The presence of large amounts of visible mold inside buildings and/or elevated indoor airborne mold levels is an indication of dampness. Many international studies have found a strong link between damp building and increased health problems, including respiratory symptoms and allergic symptoms (IOM, 2004; WHO, 2009).
Various molds can be pathogenic (disease-causing), allergenic (allergens) or toxic (poisons). Pathogenic molds do not tend to affect health people. Persons with weakened or undeveloped immune systems (including the very young and the elderly as well as the sick) are more susceptible. Pathogenic molds, especially certain types of Aspergillis, are a serious concern in hospitals (aspergillosis).
However, the main concern from mold in buildings is not as a pathogen but as an allergen or irritant (toxin). The primary exposure pathway is inhalation with ingestion perhaps also playing an important role. Inhalation involves breathing in mold. Ingestion usually involves eating moldy food but may also occur indirectly when mold trapped by mucus in the respiratory system is swallowed and ingested.
Both living and dead mold spores (and the smaller particles associated with them) may be allergens or irritants. There is some evidence that living mold is more allergenic or toxic (inflammatory) than dead mold (Cooley,et.al., 2004).
Some molds give off mycotoxins (poisons). As most persons are aware, certain mushrooms have extremely toxic poisons. Some molds may also be quite toxic. However, because spores are so tiny, very high levels of airborne mold may need to be inhaled or ingested by most persons before noticing toxic effects.
On the other hand, persons with allergic reactions may need only quite low levels of exposure to mold or other allergens to cause health symptoms. The classical allergic reaction is exposure to a high dose of the allergen (such as during a mold clean-up) followed by sensitization where a person develops an allergic reaction such that much smaller doses will then still cause an allergic reaction. While allergic reactions are often assumed to be an “over-reaction” of the immune system, there is argument that the allergic response is more complicated and more useful than a simple over-reaction (Ewald,1994). Neverthless, persons with allergies can be vastly more sensitive to an allergen than a non-allergic person. This means developing exposure guidelines adequate enough to include both allergic and non-allergic persons is virtually impossible.
Stachybotrys & the CDC - 1994
Until the early 1990’s there had been limited concern about indoor mold. The huge increase in interest can be traced back to studies done in Cleveland in 1993-1994 where several cases of infantile pulmonary hemorrhaging (bleeding lungs) occurred in water damage homes. The mold Stachybotrys was implicated as the primary cause by the famed Center for Disease Control (CDC; 1994; Etzel and Dearborn, 1999). Since that time, there has been an explosion of interest in mold lawsuits and the development of an entirely new industry involving mold testing and mold clean-ups. There has been great controversy over these original findings and the CDC has since reversed their position that Stachybotrys was the proven cause (CDC, 2000). Although there is increasing consensus that damp and moldy buildings pose health concerns, there is sharp disagreement over which molds and what symptoms can be linked to mold.
What Are Symptoms of Mold Exposure?
MTS is often asked what symptoms are associated with exposure to mold? Symptoms may be considered to fall into two groups: Limited Symptoms and Severe Symptoms.
The majority of mold problems occur as limited symptoms. These are often flu-like or allergic-like symptoms. One or more symptoms may occur and may differ among individuals. A tight chest, runny nose, sore throat, and sinus problems may occur. In some cases, fatigue and muscle ache is mentioned. For severe symptoms, extreme fatigue, confusion, memory loss, hair loss, vomiting, diarrhea and skin rashes may occur. Asthma may sometimes occur or worsen.
In general, persons with mold symptoms feel better when away from the moldy home or office and symptoms resume when they return. It may take two weeks or more away to notice the changes. The symptoms are often persistent. By contrast, disease related symptoms often show no change when away from a building and often only last a few weeks (with many exceptions).
Who Is Most At Risk?
Those most are risk are persons with weak, damaged or suppressed immune systems. Persons with allergies and asthma are at greater risk. Young children take a few years to develop their immune systems (more effective if breast fed). Pregnant women and infants should be considered a high risk group. The elderly often have weakened immune systems as do sick persons. Transplant recipients must take drugs to suppress their immune system.
When Should You Be Concerned?
Mold does not pose a concern in most buildings. Mold usually does not pose a concern on main and upper floors. The primary concern from mold is airborne exposure to high levels of problem molds. This typically requires both water damage or persistent dampness and disturbance. Mold behind a wall may pose no concern until the wall is opened up. You should be concerned where mold may be disturbed. This may include water clean-ups, mold clean-ups, etc.
Mold is often a concern when water damage occurs and is not dried out within 48 hours. Mold is often a concern during remodeling efforts. Basements, bathrooms and kitchens are favorite places to remodel and may often have concealed mold. Vacant buildings, if vacant for more than a few months, often show an increase in airborne and visible mold. Damp basement and crawlspaces are prone to mold. Old farmhouse basements are especially prone to lots of mold during clean-ups.
What is the Evidence?
IN PROGRESS – HISTORY-ANIMALS-HUMANS
Are There Health Guidelines For Mold?
IN PROGRESS- INCOMPLETE. There are various guidelines related to the clean-up of mold (NYCHD, Presant, 2008,). But there is a surprising lack of guidelines for both visible and airborne mold.
Based on our experience on doing total (nonviable cassettes) airborne mold testing at hundreds of buildings over the last 12 years, MTS has found a few major mold types are often sufficient to determine if normal or problem mold conditions. We have also found normal (non-problem indoor airborne mold levels typically fall within a fairly narrow range while problem mold levels are usually much higher (Meyer, 2009).
Is There Treatment for Mold Exposure?
IN PROGRESS – AVOIDANCE-DESENSITIZATION-REMOVAL
References
CDC, 2000, Update: pulmonary hemorrhage/hemosiderosis among infants – Cleveland, Ohio, 1993-1996, MMWR, v.49,p.180-184 (CDC reversal – no proven link to Stachybotrys)
Cooley,J. et.al, 2004, Fungi and the indoor environment: their impact on human health, p.3-27 in Straus,David, Editor, Sick Building Syndrome, Advances in
Applied Microbiology, v.55, Elsevier,NY,NY, 490p. (p.15 – viable vs dead)
Etzel, Ruth and Dearborn,Dorr, 1999, Pulmonary hemorrhage among infants with exposure to toxigenic molds: an update, pp.79-81 in Johanning, E., Editor, Bioaerosols, Fungi and Mycotoxins: Health Effects, Assessment, Prevention and Control, ENYEHC, Albany, NY, 637p.
Ewald, Paul, 1994, Evolution of Infectious Disease, Oxford Univ. Press, NY, 298p. (p.31 allergic response)
Flannigan, Brian et.al., Editors, 2001, Micro-organisms in Home and Indoor Work Environments, Taylor and Francis, New York, New York, 490p. Useful guide, information on health effects).
IOH, 2004, Damp Indoor Spaces and Health, Institute of Medicine, National Academy of Sciences Press, Washington,DC
Meyer, Michael, 2009, What are normal and problem indoor total (non-viable) airborne mold levels? An IAQ consultant’s perspective based on 10 years experience at hundreds of homes and offices in the Midwest, Healthy Buildings 2009, Proceedings. Paper 203, Syracuse, NY
Prezant,Bradley et.al., Editors,2008, Recognition, Evaluation, and Control of Indoor Mold, Am. Industrial Hygiene Assoc, AIHA, Fairfax, VA., 253p. (useful guide, information on health effects)
Web pages – see Center for Disease Control (cdc.gov) and US EPA (epa.gov)
WHO, 2009, Dampness and Mould – WHO Guidelines for Indoor Air Quality, World Health Organization, Copenhagen, Denmark (www.euro.who.int/document/e92645.pdf)
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