of Residential Buildings
The adverse health effects of fungi and their metabolites i.e.: mycotoxins are well known in the literature with regards to contamination in food sources as well as the pathogenicity of some fungi. What is not documented as well in the literature that physicians normally read are the adverse health effects of fungi and their metabolites i.e.: mycotoxins and mVOCs (volatile organic from fungi).
Recent review of the aerobiology literature has shown that the effects of airborne fungi can be quite pronounced as in Aspergilliosis (pathogenic effects of Asp. fumigatus) and quite insidious, low level, long term exposure to common fungi amplified in a building environments such as Penicillium, Aspergillus versicolor, and Cladosporium. Recent literature has reported mycotoxicosis and its related symptoms from exposure to Stachybotrys chartarum a not to uncommon slime mold found on wet sheetrock. Many other fungi are known to be mycotoxic and it has been stated that inhalation exposure may be just as detrimental as ingestion. Reactions from exposure to airborne fungi have included chronic fatigue, environmental illness, candida like symptoms and auto immune dysfunction. Candida albicans a known pathogenic organisms has been found growing on many wet substrates besides foodstuffs. These include water filters, toothbrushes, plastic shower curtains and anywhere excess moisture can accumulate.
Understanding some of the aerobiology of fungi in residential structures is important in the therapeutic intervention of many patients who are suffering. Many health practitioners do not take into account the fungal contamination load occurring from compromised living environments and there effects upon the health and well being of the occupants. Compromised living environments include damp houses from elevated relative humidity, built environments that have had a history of improperly remediated water damage and HVAC systems that have become contaminated. Recently NIOSH has stated that 30% of all indoor air quality symptoms are related to biological factors.
Fungi are ubiquitous in the environment. They can occupy numerous different niches within a built environment depending the conditions of moisture, temperature, light and air movement. Once they have found a foothold in a structure, vigorous decontamination is necessary to eliminate them. They can become a source of problems for years, due to the fact fungi spores can live for many years and established colonies can lay dormant and start growing again when conditions are favorable. Fluctuations in temperature and humidity on a daily basis can cause the intermittent release of spore, metabolites and different mVOCs (mold related volatile organic compounds) depending upon what part of the growth cycle they are in.
Symptomatic response to fungi depend upon a number of factors. They include the sensitivity of the individual to a particular fungi as in an immune mediated responses ex: allergies and inflammation, the person's immune status, the concentration and type of fungi encountered, and the amount of exposure time to the fungi. Also fungi spores do not have to be viable in order to cause adverse heath effects.
Molds can effect the health of individuals in a number of ways:
- Individuals who are sensitized to fungi can have allergic reactions (sensitization diseases) to specific mold types. Some illnesses are rhinitis, conjunctivitis, and asthma. Symptoms included are, irritated eyes, nose and throat, difficulty breathing, chronic cough, and shortness of breath,
- Acute and chronic exposure to fungi can cause inflammation reactions. Some illnesses associated with this are: chronic bronchitis, hypersensitivity pneumonitis, and airway inflammation. Symptoms included are low grade fever, fatigue, chronic dry cough, and shortness of breath. Other associated heath effects related to exposure to bioaerosols (of which fungi is considered) include systemic symptoms such as, headaches, fatigue, and joint pain.
- Certain fungi are infectious. In immune compromised individuals such as AIDS patients, cancer patients on immuno suppressive therapy, or patients having other disease causing a lowered immune system fungi can cause infections of the lungs, and other parts of the body. In some cases this can be fatal. Also, certain fungi are known to illness in normal individuals with extensive exposure, such as coccidiomycetes causing the illness Valley Fever. Some pathogenic fungi are Aspergillus fumigatus, causing aspergillosis, candida albicans causing candidiasis, and Histoplasmodia causing Histoplasmosis.
- Certain fungi produce toxic metabolites called mycotoxins. The most known mycotoxin is aflatoxin produced by the fungi Aspergillus flavus. It is commonly found in certain grain and peanuts. It is the most carcinogenic biological substance known. Aspergillus versicolor a fungi commonly found on water damaged drywall also produces known carcinogenic compounds. Some fungi produce mycotoxins called tricothcenes, these compounds have been reported to cause a host of acute symptoms including, fever, chills, diarrhea, vomiting, bleeding, shortness of breath, rhinitis, inflammation of the lungs, mucous membranes and symptoms of radiation like poisoning. The most infamous of these fungi is Stachybotrys chartarum, it has been linked by the Center of Disease Control to the death of one infant and the severe illness of 10 others in Cleveland in 1994. These infants came down with pulmonary hemisiderosis an acute lung disease which cause bleeding in the lungs. Mycotoxins reactions can be caused by either dermal contact, inhalation or ingestion.
Research is just beginning on the chronic effects from long term exposure to mycotoxins. Cancer probably associated with low level mycotoxin exposure has been reported in peanut handlers, mycotoxin researchers, and in several farm related cases.
- Molds emit odors which are volatile organic compounds (mVOCs) and may produce significant adverse health effects in high concentrations. These compounds can cause mucous membrane irritation and may be involved in or produce symptoms (headache, nausea, dizziness) that mimic sick building syndrome.
Fungi need to be taken seriously in any condition within the built environment an d where they can become a established. They can become act a source for continued exposure to individuals occupying that environment for years.
Remediation of fungi in the built environment
Procedures for eliminating molds in the indoor environment are based on certain two simple concepts.
- All visible mold growth have to be eliminated by removal of fungal sources or reservoirs.
- Conditions that support the growth of molds have to be changed.
Procedures for the elimination of molds in the built environment can range from very simple to very complex. This is dependent upon the amount of contamination, the location of the fungal reservoir, the extent of contamination, and the types of fungi inhabiting a structure.
For small jobs:
Wipe down all visible mold growth, such as in the bathroom, on aluminum framed windows, and in areas within closets with 20:1 Chlorox Clean or straight hydrogen peroxide with a detergent. Small jobs are any visible mold growth less than 2 square feet of contamin- ation. Wearing a respirator during clean up is recommended. If materials have to be removed, bag all contaminated materials. If the molds grow back then either the conditions for fungal growth have not changed or their is a larger fungal reservoir and the visible growth was only the tip of the iceberg.
For larger jobs > than 2 square feet:
- Protect yourself when removing or disinfecting materials that are contaminated. The use of a respirator with HEPA and organic cartridges is essential to minimize exposure. Cartridges can only be used for 8 hrs and must be disposed of, molds can grow in cartridges. Wearing painter's coveralls or a tyvek suit which can be disposed of will minimize dispersing spores into non enclosed areas.
- Enclose the area that is to be remediated with plastic and set up preferably a negative containment within the area. Use a HEPA air filter to capture released spores.
- Bag all contents that have been removed and throw out.
- HEPA vacuum and simultaneously wire brush all remaining structural materials.
- Wipe down surfaces with a surfactant based disinfectant and dry.
(20:1 Chlorox Clean)
- Wipe down and vacuum all surfaces within the enclosed area to remove residual spores.
- Run the HEPA air filter for few days afterwards to clean the air.
- Replace the HEPA air filter.
- Extensive mold contamination greater than 30 square feet should only be remediated by a trained professional and should be evaluated by an environmental specialist experienced in mold contamination evaluation and remediation.
Changing the environment that supports mold growth.
Moisture is the may source of mold growth. Other factors involved that support mold growth are reduce light, minimal air movement and moderate temperatures. A good example of this is the wall closet adjacent to an exterior wall. The cold wall causes moisture to condense on the surface of the interior side of the wall in the closet. The lack of air movement, along with darkness and moderate temperatures causes molds to grow on the wall. A fix for this situation would be to increase the ventilation by putting holes in the lower part of the door to the closet and adding a low wattage light to the closet. A better fix would be to insulate the exterior wall cavity.
An inspection of the conditions that cause moisture to enter the built environment is necessary. The following conditions should be remedied:
- All water leaks into the building.
- Water intrusion into basement, crawlspace or into a cement slab from improper drainage.
- Poor exhaust routes for moisture from dryers, laundry rooms and bathrooms.
- Carpets in bathrooms and kitchens.
- Excessive condensation on the windows indicating elevated relative humidity.
- Relative humidity above 60%.
- Elimination of microbial and moisture laden air from the crawlspace, or basement through openings in the building through the subfloor, (wiring and plumbing openings) and openings in the duct system. This can be done by sealing all openings and sealing all ducts junctions with water soluble mastic and tape.
Air scrubbers are needed to lower the outside infiltration and should be used as a stop gap measure to remedy the above problems. But if the above problems exist the use of air scrubbers (HEPA air filters) will only be marginally effective as the microbial load will be high. Conditions will return rapidly when the air scrubber is turned off.
The use of ozonators and citrus extracts to kill molds are not recommended and some cases detrimental. Ozone is a toxic irritant which can adversely effects the lungs. It will reduce odors but their is very little literature indicating it will kill airborne organisms. Even if did kill airborne organisms, these molds are toxic dead or alive. The use of citrus extracts has not been researched, but the concept is flawed. Molds are toxic and allergic both dead and alive.
R. David Bierman is an environmental consultant with extensive experience in conducting residential indoor air quality assessments. He is the owner of Safe Environments Home & Office Testing Services an environmental consulting firm specializing in indoor air quality testing, biological monitoring of sewage and fungi contamination, electromagnetic field analysis, asbestos and lead testing. Please call us if you have any questions.
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