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| WINTER 1998 |
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• MOULD — A Growing Health Concern in Buildings
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MOULD — A GROWING HEALTH CONCERN IN BUILDINGS
By Patrick Morrissey & Jim BagleyWhy Worry About Mould Growth in Buildings?
Although moulds are naturally occurring, when they begin to grow in a building, they may cause a variety of health problems in the residents, occupants or workers in the building. There has been a growing recognition in the past decade that occupants can have harmful exposures to certain fungal species growing in buildings, that either produce diseases (the pathogenic moulds), or contain poisons on the surface of the spores (mycotoxin-producing or toxigenic moulds). The following are a few case histories to consider:
The Case of Concern – Over the past four years in Cleveland, Ohio there have been 34 cases of pulmonary hemorrhage and hemosiderosis (PH/H) in infants. Ten of the infants have died. All but five cases have occurred within seven contiguous zip code areas. An investigation was subsequently prompted by the Centers for Disease Control and Prevention (CDC) and several lines of evidence suggest the most likely causal agents are fungal toxins from a fungus called Stachybotys atra. The linkage of Stachybotys to PH/H is on the basis of epidemiological data and has not been conclusive demonstrated. The spores of this particular fungus contain very potent mycotoxins, which appear to be particularly toxic to the growing lungs of infants. A concern exists that there may be a larger number of undetected young infants with this disorder which has lead to further investigation of coroner cases over the past three years. The investigation revealed six "SIDS" (sudden infant death syndrome) cases with evidence of preexisting pulmonary bleeding.
The Eastern Canada Experience – Pinchin Environmental was retained to conduct an indoor air quality investigation after the discovery of a water leak in a portable classroom within a school district in Ontario. Mould was found to be present on drywall surfaces upon which students were relocated and a thorough investigation took place. The fungus Stachybotys atra was recovered during the investigation. Water infiltration occurrences were rectified and remediation efforts immediately deployed.
In Western Canada – Hazardous moulds have been recovered during investigations within schools districts, commercial high and low-rise buildings and building envelope failures.
What is Mould or Fungus?
A mould or fungus is a microscopic, plant like organism that grows on organic material and reproduces by broadcasting spores. In proper usage, "mould" refers to a group of plant disease-producing fungi that grow on crops, but in common use refers to any type of fungus. Moulds are found throughout the natural world, and are essential in the recycling of organic material in our forests, lawns and gardens. All require relatively damp environments to grow.
Stachybotrys microbial growth
What are the Health Effects of Mould Exposure?
1. Allergic response: When spores are airborne or the fungal mass is disturbed, occupants with pre-existing allergies to moulds may react with running nose, eye and throat irritation, cough, etc. Prolonged exposure may result in development of allergies in individuals who did not have an allergy to mould before. Asthmatics may react with more frequent and severe asthmatic attacks.
2. Toxic response: A variety of symptoms have been associated with the toxigenic moulds, including headache, sore throat, cough, skin rash, flu symptoms, nosebleeds, fatigue, fever, etc. Stachybotrys chartarum is one of the more common fungi with toxigenic effects, but many other toxigenic moulds are known. High exposures to Stachbotrys chartarum have been implicated in several cases of infant death in homes.
3. Infectious disease: Exposure to a few types of pathogenic moulds can result in infectious lung diseases. Although these diseases are normally limited to the high exposures encountered during renovation or demolition of contaminated buildings, lower exposures may also be a concern with individuals with reduced immune systems and young children. Bird and bat droppings are often infected with pathogenic moulds, and are a special concern in renovations and demolition of older buildings.
Who Is At Risk?
1. Persons with allergies or asthma may react to the presence of any mould.
2. Anyone may react to toxigenic moulds. There is insufficient evidence at this time to establish "safe" or no-effect exposure levels for the toxigenic moulds.
3. Infants and young children, individuals with reduced immune function, or those with pre-existing lung disorders, may have a more severe reaction to infectious or toxigenic moulds.
4. Maintenance, renovation, and agricultural workers may experience very high exposures during disturbance of contaminated building surfaces.
Are There Regulations or Guidelines That Apply To Mould in Buildings?
Municipal Public Health departments have the authority to issue orders to building owners regarding potentially hazardous mould growth in occupied buildings, and have exercised this authority in some Ontario municipalities. A working group representing federal and provincial health departments has published a very useful document, "Fungal Contamination in Public Buildings: A Guide to Recognition and Management", June 1995.
How Would I Investigate a Mould Problem?
Suspected mould problems can be difficult to investigate, especially since the reported signs and symptoms have many other potential causes, such as poor air quality, seasonal allergies, and common infections such as colds and the flu. In order to separate mould concerns from other issues, you should consider at least the following lines of investigation.
1. Health investigation: Although this can be a difficult issue to broach, the investigation has to gather information from the occupants or employees regarding any problems they might associate with the building. Of special concern would be reports of headache, nose or throat irritation, rash, allergy-like reactions, or fatigue, especially if these symptoms clear when out of the building.
2. Building inspection: Mould needs water intrusion to grow, and the investigation must consider the history of roof leaks, leaking pipes, floods, wet basements, etc. Carefully look for signs of water damage, stained surfaces or deterioration. Although the water problem may have been fixed, the hazard will remain until abated, since the mouldy materials remain hazardous even after the surfaces have dried and further growth has stopped.
3. Air monitoring: Air sampling is often useful to check for the possibility of hidden growth, within wall cavities, in crawlspaces, within ductwork or air conditioning equipment, etc. Indoor air samples are compared to outdoor samples, and if substantially different, point to a growth of mould in the building.
What Can be Done to Remedy a Mould Problem?
Small areas of fungal growth can be removed by the homeowner or maintenance worker. The area should be isolated, workers wear respirators with high efficiency filters, porous mouldy materials are removed, and any remaining mould is treated with a bleach solution. Authorities advise that you should seek specialized help for the remediation of more than two square feet of mould growth, as special containment and personal protective measures are required to protect workers and prevent the spread of contamination.
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