The Impact of
Environmental Molds in the Home
Anthony Montanaro, MD, on medscape.com, 2002
Introduction
A fascinating review of the potential human health
impact of environmental molds was presented during the recent 60th Annual
Meeting of the American College of Allergy, Asthma and Immunology. In the
initial presentation, undertaken by Elliott Horner, PhD,[1]
Microbial Laboratory Director at Air Quality Sciences, Inc. in Marietta,
Georgia, it was pointed out that environmental molds potentially can
result in human illness by the production of allergens, proteases, beta-glucans,
and volatile organic compounds. Dr. Horner further emphasized that in
order for molds to grow, they require moisture. The temperature tolerance
of molds is extremely variable. The ecologic types of molds are those
included in the classes of phylloplane, which are molds that can grow on
leaf surfaces. These molds include Cladosporium and Alternaria.
Soil-based molds are typified by Penicillium and Aspergillus.
Typical molds found in wood decay include the Basidiomycetes.
Indoor molds typically include Alternaria, Cladosporium, and
Epicoccum, but Dr. Horner pointed out that these are typically from
outdoor sources. Dr. Horner pointed out that in interpreting industrial
hygiene reports on mold measurements, colonization vs contamination must
be determined. When mold contaminates, the mycelial elements will actually
penetrate the substrate. The mycelium is connected to the conidiophore,
which is the reproductive structure of the mold. The food source for
fungal growth in buildings may include cellulose, which can be found in
ceiling tile, insulation, sheetrock, as well as wood and dirt.
Biology of Mold in the Home
Dr. Horner reviewed potential detection methodology for
molds. These include the use of direct microscopy or culture-based
methods. Dr. Horner stated that use of "settle plates" are no longer
considered a reliable methodology. Dr. Horner further noted the importance
of taxa identification, which is much more important than the absolute
number of colony-forming units. Taxa identification may allow comparisons
of indoor vs outdoor taxa.
Doing an Effective Home Assessment
M. Joseph Fedoruk, MD,[2] of Exponent and
Associate Clinical Professor at the University of California, Irvine,
California, further elaborated on the importance of home inspections when
evaluating potential mold contamination. Dr. Fedoruk pointed out that the
home inspection industry is essentially unregulated. He noted that many
home inspectors for mold contamination, in fact, are qualified only by
attending a meeting without any subsequent testing. Dr. Fedoruk noted the
importance of visual inspection of potential moisture intrusions,
including inspection for the presence of staining or discoloration. He
also pointed out that odor detection can be quite important and noted that
"if you can smell mold, you have a problem." Dr. Fedoruk also reviewed air
testing methodology surface dust analysis and noted that, in many cases,
"destructive testing" is necessary. He pointed out that this destructive
testing requires actual destruction of walls or floors.
Dr. Fedoruk also highlighted the importance of measuring both indoor
and outdoor levels of molds as has previously been noted. He further
pointed out that both complaint and noncomplaint areas of homes must be
evaluated. He re-emphasized that both direct microscopy as well as culture
identification must be undertaken. Dr. Fedoruk also mentioned that a
specific number of colony-forming units are rarely of any benefit.
Evaluating Patients for Mold Exposure
Emil J. Bardana, Jr., MD,[3] presented the
Jean S. Chapman Keynote Lecture on the potential human health effects of
mold contamination. Dr. Bardana presented the historical background of
mold sensitivity by pointing out that indoor air quality problems had
actually begun in approximately 1973, following the oil embargo and
subsequent efforts to conserve energy. Subsequently, in 1994, a paradigm
shift had occurred in which individuals who had previously been diagnosed
with "sick building syndrome" were subsequently informed that they were
potentially suffering from "toxic mold syndrome."
Dr. Bardana highlighted the fact that in any well
constructed home without evidence of water contamination, significant
levels of airborne fungi can be measured. Dr. Bardana noted that these
airborne fungi typically reflect outdoor levels of fungi. Furthermore, it
was noted that fungi are ubiquitous and, in fact, account for at least 25%
of the earth's biomass. Dr. Bardana again emphasized that while there were
guidelines for the assessment of mold contamination in homes, there had
been no uniformity or agreement of any specific level that could
potentially result in human disease. In addition, there has been no
established dose-response relationship between mold levels and human
disease. Dr. Bardana gave examples of sawmills that had been evaluated
that revealed workers without symptoms exposed to 1.5 M cfu/m3.
In addition, there have been studies of farmers without symptoms who were
exposed to 120 M cfu/m3.
Dr. Bardana reviewed the 6 types of human responses associated with
mold exposure. These responses include:
-
Potential irritant effect, which
at best is mild and transient and may be associated with exposure to
beta-1,3 glucans or volatile organic compounds;
-
Nonspecific respiratory
symptoms, which are poorly correlated to airborne fungal levels;
-
Allergic sensitization, which is
usually not considered to be severe and is usually not considered to be
a major problem and is more problematic with outdoor exposures;
-
Fungal infections, which mostly
arise from outdoor sources and may occur from exposure to soil-based
saprophytic fungi;
-
Exposure to mycotoxins, which
have recently been described. There are currently more than 300
mycotoxins that have been described that are low in molecular weight and
nonvolatile in nature. Dr. Bardana highlighted the fact that all species
of fungi are capable of producing mycotoxins; and
-
Psychogenic effects, which can
occur when an individual perceives that he or she is being harmed by the
effects of fungal exposure.
These potential health effects of indoor fungal bioaerosol exposures
are highlighted in a recent publication.[4]
Finally, Dr. Bardana outlined the recent health
concerns of individuals exposed to species of Stachybotyrs. Dr.
Bardana reviewed the fact that Stachybotyrs has been referred to as
toxic or "black mold." Dr. Bardana highlighted the fact that there were,
in fact, no bona fide reports of human infection in the medical
literature. Reports of potential allergic disease have been characterized
as being inconclusive. In fact, Dr. Bardana highlighted a recent
observation that pointed out that half of blood donors have immunoglobulin
(Ig) G antibody to Stachybotyrs, with 9% of these individuals
having evidence of IgE to Stachybotyrs. Given the ubiquitous nature
of Stachybotyrs, it is not considered to be unusual that one would
observe these findings. Dr. Bardana further noted that there have been no
reports of allergic alveolitis or sinusitis due to Stachybotyrs.
Although there have been recent concerns regarding the potential of "toxic
encephalopathy and Stachybotyrs," Dr. Bardana pointed out there has
been "no scientific link." Dr. Bardana suggested further reading on the
potential role of Stachybotyrs in a recent publication by the
American Industrial Hygiene Association.[5]
The potential human effects of mold exposure have led
to a new legal industry with devastating impact on the immune insurance
industry. A recent example of mold litigation occurred in Texas, where a
jury determined that an insurance company acted fraudulently and in bad
faith when fixing water damage in a 22-room mansion.[6] This
particular case resulted in a delay in the repair of what many considered
a relatively small innocuous water leak but awarded the homeowner with a
multimillion dollar verdict. It is pointed out that the number of
mold-related claims in the State of Texas alone rose from 7000 in the year
2000 to 37,000 in the year 2001! These claims were further fueled by the
presence of tropical storm Alison, which occurred in June of 2001 and
affected the Houston metropolitan area for approximately 2 days, resulting
in massive flooding along the Gulf Coast. In Houston alone, there was a
58% increase in claims, representing 2.96 claims for every 1000
households. There have been many high profile lawsuits reported in the
press, including that of Johnny Carson's ex-sidekick, Ed McMahon, who
brought suit against his insurance company for 20 million dollars in April
of 2002 for the death of his dog, which was alleged to have been due to
exposures to mycotoxins from Stachybotyrs chartarum. Sports stars
have not been immune from this weight of litigation. Michael Jordan has
required that his home in the Washington, DC area at the Ritz-Carlton
Hotel have extensive renovation due to the perception of mold-related
problems. The celebrity status of some of these claims has resulted in
increased hysteria in the general population. The ultimate effect of this
hysterical response to suspected phoma-related problems has had a
tremendous impact on the insurance industry, with more than 1.3 billion
dollars spent in 2002 to settle lawsuits and mold-related damages.[7]
Unfortunately, the response from the insurance industry has clearly been
to settle cases and to attempt to no longer put themselves at risk of
covering potential mold-related damages. Recently, the State Farm Mutual
Automobile Insurance Company has attempted to eliminate coverage from
mold-related damages in 33 states.
There is little doubt that mold can indeed result in human disease.
Mold exposure can result in allergic rhinitis, allergic asthma, allergic
sinus disease, and pulmonary hypersensitivity pneumonitis. Despite the
fact that there is no doubt that mold can result in human disease, aside
from these specific incidences, there was very little data to support
human disease caused by "mycotoxins." All of the presenters emphasized the
need for further research in this area.
References
-
Horner E. General sessions. Environmental molds: biology of molds.
Program and abstracts of the 60th Annual Meeting of the American College
of Allergy, Asthma and Immunology; November 15-20, 2002; San Antonio,
Texas.
-
Fedoruk J. General sessions. Environmental molds: home assessments: how
they are done. Program and abstracts of the 60th Annual Meeting of the
American College of Allergy, Asthma and Immunology; November 15-20,
2002; San Antonio, Texas.
-
Bardana EJ. General sessions. Environmental molds: Jean A. Chapman
Lecture. Health effects of mold exposure and how to evaluate patients
who think they have it. Program and abstracts of the 60th Annual Meeting
of the American College of Allergy, Asthma and Immunology; November
15-20, 2002; San Antonio, Texas.
-
Fung
F, Hughson WG. Health effects of indoor and fungal bioaerosol exposure.
Proc Indoor Air. 2002;1:46-51.
-
Page
EH, Trout DB. The role of Stachybotyrs mycotoxins in building-related
illness. Amer Indus Hyg Assoc J. 2001;62:644-648.
-
Sharp
R. Mold getting a costly hold on homes. USA Today. June 19, 2002.
-
Cahill SF. For some lawyers mold is gold. Amer Bar
Assoc J. December 2001.
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