by Webscape from WebMD
Anthony Montanaro, MD 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:
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 Stachybotrys. Dr. Bardana reviewed the fact that
Stachybotrys 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 Stachybotrys, with 9% of these
individuals having evidence of IgE to Stachybotrys. Given the ubiquitous
nature of Stachybotrys, 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 Stachybotrys. Although
there have been recent concerns regarding the potential of "toxic encephalopathy
and Stachybotrys," Dr. Bardana pointed out there has been "no scientific
link." Dr. Bardana suggested further reading on the potential role of
Stachybotrys 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 Stachybotrys
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