A Proactive Approach to the Problem of Indoor Mold
By
Leonard V. Zumpano
Alabama Association of Realtors® Chair of Real Estate,
Executive Director, The Alabama Real Estate Research and Education Center,
and Professor of Finance
and
Suzanna Hartley
Resource Specialist
The Alabama Real Estate Research and Education Center
The College of Commerce and Business Administration
The University of Alabama
Submitted to
The Research Division of The National Association of Realtors®
February 25, 2002
1
2
Table of Contents
Section
Page
I
Introduction
1
II
What is Mold?
2
III
The Health Effects of Molds.
3
IV
How Serious is the Health Threat from Mold?
5
V
The Causes of Indoor Mold Growth
How Widespread is the Mold Problem?
8
9
10
VI
Mold and Structural Integrity Issues
16
VII
Remedial Action
18
19
22
24
mold: A New Problem?
Inspections
Remediation
Summary
VIII
Mold Prevention
General Prevention Recommendations
Building Code Considerations
Mold Disclosure
25
25
28
30
IX
Insurance Issues
33
X
Summary and Conclusions
36
Appendix A Specific Illnesses Associated with Exposure to Mold.
Allergies
Infection
Mucous Membrane and Trigeminal Nerve Irritation
Adverse Reaction to Odor
Toxicity
Aspergillus
Stachybotrys chartarum (atra)
37
37
37
38
39
39
41
42
Limitations in Sampling Methodology, Toxicology, and Epidemiology of
Toxic Mold Exposure
Appendix B
Bibliography
3
Controlling Mold Growth in the Home
44
46
54
A Proactive Approach to the Problem of Indoor Mold
I. Introduction
Over the last few years a new problem has arisen that may have very important
consequences for both current and future homeowners, government regulators, and real
estate industry professionals. The problem is indoor mold. Although this subject is
gaining increasing national media attention and has become the subject of a growing
number of lawsuits, little is really known about the extent and significance of the mold
problem. How widespread is the incidence of mold? Under what conditions and in what
locations is it most likely to occur? What and how serious are the health problems linked
to mold exposure? What can be done to combat and prevent mold infiltration into homes,
apartments, and the workplace? Should health and building codes be modified to help
solve the problem? These and other questions have yet to be satisfactorily addressed.
One of the primary goals of this study is to try and provide some definitive answers to the
above questions as they relate to the real estate industry. In doing so this research will
help industry leaders formulate proactive policy initiatives that will best serve the real
estate industry, as well as educate real estate professionals about how to deal with the
problem of indoor mold. This, in turn, will allow them to better serve theirs customers
and clients, while reducing their exposure to legal liability.
This study is based upon an extensive review of the existing literature and source
material on the subject of problems with indoor mold. Our goal was to seek out the most
authoritative sources of information. It includes reviews of materials from the EPA, the
CDC, state and municipal agencies, major research universities, the home building,
1
insurance, and inspection industries, medical studies, and newspaper articles. The
Internet proved an invaluable source of information. Individuals identified in the
literature as having expertise in this field were also contacted. One of the problems
encountered in this study is that to date, despite considerable scientific and medical
evidence, there is still no consensus on just how serious a health threat indoor mold
represents. Nor have standards yet been developed for safe exposure levels for the
various types and strains of mold encountered in homes, schools, and at the work place.
This research synthesizes the information collected for this study and provides a
consensus of opinion on the mold related issues identified in the text. Although this
review has been extensive, it is simply not possible to read and assess all the information
that is out there on mold, a lot of which proved to be redundant. Consequently, we were
forced to exercise editorial judgment as to which sources to include and cite in this study.
Studies, articles, and reports that were largely opinions, contained statements or claims
that had no supporting documentation, or were not based upon scientific evidence, were
excluded from this report. We believe what follows is an objective assessment of the
most important and reliable information currently available on the subject of mold.
II. What is Mold?
Mold is but one type of fungi or plant that exists in virtually every location across
the globe. The fungi family also includes mildews, yeasts, and mushrooms. While some
types of mold can cause serious health problems, other, like those found in some cheese,
antibiotics, and those that break down organic material, are beneficial.
2
Molds reproduce by releasing spores that are commonly spread through the air
and find their way into homes via windows, open doorways, and air conditioning,
ventilation, and heating systems. Spores also can gain entry into homes by attaching
themselves to pets, people, clothing, and shoes. Some can also be ingested.
In the U.S. there are approximately 1,000 types of mold, of which only 24 are
considered potentially hazardous to people.1 Unfortunately, identifying harmful mold is
made more problematic because individual mold type may have many different strains or
species, some of which are more harmful than others, while other strains of the same type
of mold are relatively innocuous.
Toxic molds generally refer to molds that release mycotoxins; poisonous
substances found on or within mold spores that protect the spore from other types of
spores and other forms of vegetation. However, there is no one agreed upon definition of
what constitutes toxic mold, and many scientists view the term as alarmist, popularized
most commonly by the news media and lawyers. Public health experts also point out that
we should be just as concerned with mold species that release allergens. Some molds
also release harmful substances known as microbial volatile organic compounds
(mVOCs) that are produced by primary or secondary metabolism and become airborne.
For the purposes of this study harmful mold is defined to include any mold type or strain
that has been linked to health problems in humans and or structural damage to buildings
and their contents.
See “Black Mold, Mildew and Spores, Oh My!” by Judson Fambrough in Tierra Grande. Vol. 8, No. 4,
October, 2001 and “Black Mold: Between Hype and Hysteria” by David Jones, Real Estate Center News
Release, No. 4, September, 2001, recenter.tamu.edu/news/4-0901.
1
3
III. The Health Effects of Molds
Mold has been linked to a wide variety of illnesses, from bloody noses, nausea,
diarrhea, hay fever like allergic symptoms, skin and throat irritation, respiratory problems
such as asthma, hemorrhaging, neurological disorders such as headaches, memory loss,
and even cancer.
Allergies are probably the most common reaction to contact with molds.
Individuals who are exposed to mold, mold spores, or mold byproducts may display
allergic reactions once they become vulnerable or sensitized to a particular mold. The
allergic reactions can range from very mild and temporary to acute, chronic illnesses.
While there are many other causes of allergies such as dust mites and effluvia from pets,
mold in the home and workplace is becoming increasingly suspect as a major source of
many common allergic reactions. It has been reported2 that about 10 percent of the
population is severely allergic to mold.
According to the Centers for Disease Control and Prevention (CDC) the types of
mold most commonly found in households are Cladosporium, Penicillium, Aspergillus,
and Alternaria, and less commonly, Stachybotrys chartarum.3 The specific types of
problems associated with mold are largely a function of the type of mold encountered, the
degree, concentration, and length of exposure, and the susceptibility of the victim. People
with chronic respiratory disease or weakened or compromised immune systems are more
vulnerable to mold toxins and infections.
Stachybotrys chartarum, sometimes called stachybotrys atra, or black mold has
garnered the most media attention. It is a greenish-black fungus that is found throughout
2
3
Ibid.
See www.cdc.gov/nceh/asthma/factsheets/molds/default.htm
4
the world and is typically wet and slimy to the touch. It is associated with a whole host
of symptoms, but the most serious are respiratory illnesses such as idiopathic pulmonary
hemorrhage, which can prove fatal in infants. However, Aflatoxin B1, a mycotoxin
produced by two strains of Aspergillus, flavus and parasiticus, is one of the most potent
carcinogens known. Here too, however, you need to avoid media hype and undue
hysteria. Neither of these species of the Aspergillus mold is commonly found on building
materials or in indoor environments. So far, more than 200 mycotoxins have been found
in molds and many more remain to be identified.
IV. How Serious is the Health Threat From Mold?
The answer depends upon whom you ask. Although there have been a number of
reported cases that certain molds found inside homes can cause serious illnesses, the
CDC has yet to find a causal link between the presence of “toxic mold” and specific
health symptoms. Many of the problems associated with mold have been based upon
animal studies and do not have strong links to human health problems. To date, the CDC
reports that a possible association between acute idiopathic pulmonary hemorrhage
among infants and Stachybotry chartarum (atra) has not been proven.4 The California
Department of Health Services also points out that there is, as yet, no laboratory tests of
blood, urine, or other bodily components that can determine even whether a person has
been exposed to mycotoxins.5
Most health experts acknowledge that certain strains of mold can trigger allergic
reactions, asthma, and other respiratory illnesses, and that species of the Aspergillus
4
This refers a cluster of cases of pulmonary hemorrhage and hemosiderosis in infants which occurred in
Cleveland, Ohio between 1993 and 1994. One of the findings was that all the homes of these infants had
high levels of S. charatarum mold. JAMA, Vol. 283, No.15, April 19, 2000
5
mold can cause cancer. While researchers and physicians at the Mayo Clinic have
concluded that mold causes most chronic sinus infections6, skeptics point out that it has
proven much more difficult to link neurological symptoms such as memory loss,
headache, and learning problems to the presence of mold.
Still the growing weight of medical evidence indicating a strong association
between certain types of mold and serious health problems and recent media attention has
heightened awareness about the harmful effects of mold.7 Since CBS aired a “48 Hours”
feature about mold last March, newspaper accounts across the country have picked up the
story. In June of 2001 a Texas jury awarded a home owner $32 million in a case
involving an insurance company’s delay in repairing damage caused by a plumbing leak,
which in turn, caused extensive mold damage to the structure and health problems for the
occupants.8 Homeowners, not surprisingly, have sought out home inspectors, and when
mold is found, have made claims on their homeowners insurance. State Farm Insurance
reports that the number of mold related claims in Texas alone has increased by 65% since
January 2001.9 The Austin Business Journal (October 15, 2001) reported that mold
related claims in Texas have risen by 135% since 1999. Over the last three years
approximately 10,000 mold-related suits have been filed in the U.S. and Canada.10
The federal government, the courts, and state legislatures are also acting. Time
Magazine reported that The Department of Housing and Urban Development has already
5
See www.sacbee.com/content/home/real_estate/story/1497496p-1574225c.html CDHS Study reference ?
?/
6
As reported by Time Magazine on Time.Com on January 24, 2001 and “The Diagnosis and Incidence of
Allergic fungal Sinusitis” The Mayo Foundation for Medical Education and Research, 1999
7
See Appendix A of this study for a review of this medical evidence.
8
This suit was brought by Melinda Ballard against Farmers Insurance Group.
9
Source ?
10
Source: toxlaw.com
6
paid out approximately $5 million to clean up mold problems in low-income homes.11
HUD’s Healthy Home Initiative has set aside $10 million targeting housing related
childhood diseases, including asthma and mold related illnesses. In California, as will be
pointed out in more detail in a subsequent section of this study, the state legislature has
recently mandated seller disclosure of known mold problems within residences.
What everyone agrees is that more research is needed to determine just how
serious a health threat is presented by mold. The Institute of Medicine is conducting a
comprehensive review of the scientific literature on the association between damp indoor
environments and respiratory, allergic, and related health problems. Funded by the U.S.
Department of Health and Human Services, the project should take 15 months to
complete.12 On October 7 the California legislature passed the Toxic Mold Protection
Act of 2001. Among other things, the Act directs the California Department of Health
Services to consider adopting, if scientifically feasible, permissible exposure limits
(PELs) for exposure to molds.
Until more is known about its harmful effects, mold must be treated as a potential
health threat and dealt with accordingly. We can at least identify those people most at
risk and can link, if only tentatively, specific symptoms with specific types of mold.
Because the categorization of mold types and species and the conditions they may cause
is relatively technical, this discussion can be found in the appendix to this study.
Although anyone can be adversely affected by exposure to mold, the following
population segments appear to be at higher risk for adverse health effects of mold:
1. Persons with allergies to mold or asthma may react to the presence of any mold.
11
12
Source ?
See www4.nas.edu, project identification number HPDP-H-00-06-A.
7
2. Anyone may react to toxigenic molds or high levels of other molds. There is
insufficient evidence at this time to establish “safe” exposure levels for the
toxigenic molds.
3. Infants and young children, individuals with reduced immune function (people
with HIV infection, cancer chemotherapy, liver disease, etc.), those with preexisting lung disorders, or multiple chemical sensitivity may have a more severe
reaction to infectious and toxigenic molds.
4. Maintenance and construction workers in buildings are at risk if moldy materials
or bird or bat droppings are disturbed without appropriate precautions.
5. The elderly.
6. Pregnant women.
V. The Causes of Indoor Mold Growth
What causes mold to grow indoors? Although there are some uncertainties
regarding all the harmful consequences of mold, there is no question as to the causes of
mold growth in the home or workplace. For mold to thrive three conditions are required:
moisture, a source of nutrients, and appropriate temperatures.
Without water mold cannot grow. Water intrusion into structures can result from
leaks in plumbing systems, condensation from HVAC systems, wind driven rain that
penetrates a building’s exterior envelope, or high humidity. A humidity level greater
than 50% is considered to a water source.
8
Any form of organic matter is a food source for mold. Common nutrients found
within structures include drywall, wallpaper, ceiling tiles, plaster, insulation, wood,
carpeting, books, and even clothing.
The temperature range for mold growth is quite wide, ranging from 40°F to
100°F, but it grows best between 68°F and 86°F. While the Southern states are prime
targets for mold infestation, mold’s ability to tolerate relatively cool temperatures means
mold can be found virtually everywhere in the U.S. Even in cold climates, summertime
temperatures are often high enough to support mold growth.
A related factor is light. Most mold types prefer darkness or low light. This
explains why mold is typically found inside walls, within building cavities, in attics, and
basements, and much less commonly in primary living areas where there is generally
more light.
Mold: A New Problem?
If mold has been with us since biblical times, as many researchers are fond of
pointing out (see Leviticus 14:33 to 45), why has it been the subject of so much recent
attention and concern? Although somewhat speculative, we can offer the following
considerations by way of explanation.
Newer homes are more energy efficient than older structures. Because they are
more tightly “wrapped” they allow less air ventilation and exchange of air between the
inside and outdoor environment. As a result water takes more time to evaporate in these
structures. Most homes now use central heat and air conditioning systems; mold
infecting HVAC systems can spread mold throughout a structure. Newer building
technologies that employ synthetic stucco or foam backed vinyl siding exterior cladding
9
systems have been linked to mold growth because they trap moisture within structures.13
Some claim that part of the problem is due to the use of cheaper building materials such
as plywood and plasterboard.
Lifestyle changes may also play a role in the public’s greater exposure to mold.
Home computers and video games have become ubiquitous and families are spending
more time indoors than before.14
There have been a number of highly visible mold infiltration cases and mold
related lawsuits that have resulted in very sizeable jury awards.15 The resulting increased
media attention and reporting of the potentially serious health problems mold represents
for occupants have raised the public’s concern over the problem. Homeowners and
building maintenance people, now that they have alerted to the problem, are actively
inspecting for mold infestation.
How Widespread is the Mold Problem?
A 1999 Mayo Clinic study linked nearly all the chronic sinus infections that
trouble approximately 37 million Americans to mold.16 Recent studies have also linked
mold to the tripling of the asthma rate over the past 20 years.17 A 1994 Harvard
University School of Public Health study18 of 10,000 homes in the U.S. and Canada
found that over half had water damage and mold. The presence of mold was, in turn,
associated with a substantially higher level of respiratory problems. A brochure
prepared by the American Lung Association and the U.S. Consumer Products Safety
“Insurers Blanch at Proliferation of Mold Claims”, The Wall Street Journal, May, 6, 2001. Cite study.
For example, the Texas Department of Health reports that Texans spend about 90% of their time indoors.
Fambrough, p. 25.
15
Source ?
16
“The Diagnosis and Incidence of Allergic fungal Sinusitis” The Mayo Foundation for Medical Education
and Research, 1999.
17
Source ?
13
14
10
Commission estimated that one third to one half of all structures within the U.S. have
damp conditions that can encourage mold growth.19
Another way to assess the scope of the mold problem is to look at the number of
mold related lawsuits. This may provide us with a geographic sense of how pervasive the
problem is and where, geographically, it appears to be most severe.
The Policy Holders of America tracks lawsuits involving homeowners and their
insurers. Between 1987 and January 2002, 16,059 cases reported have been reported to
this organization.20 Lawsuits have been filed in every state within the U.S. with at least 8
claims reported in each state. West Virginia and the District of Columbia have the fewest
cases, while Texas, California, and Florida have the highest number of first party
insurance cases. Table 1 lists the number of suits by state; this data is also displayed
geographically on the accompanying maps.
As can be seen from the map, although the total number of cases is greatest in the
Southern part of the country, the mold problem is much more widespread geographically
than it first appears when displayed the basis of total claims. When cases are mapped per
100,000 people and per 100,000 households, Western and even Northern states, such as
North Dakota and Alaska, appear to have serious mold related problems.
These results have to be interpreted with care for a number of reasons. The
claims only include cases against insurance companies by homeowners. Claims against
builders and home sellers are not included in the database. Over the last three years, at
18
www.bbjchem.com/news, December 3, 1999; usaweekend.com/99_issues/991205/991205mold
For a list of sources on mold related studies see the EPA’s website,
www.epa.gov/iap/pubs/moldresources.html. Cite ALA or USCPSC material
20
Source ?
19
11
least 1,000 cases have been brought against former owners, 2,000 against builders, and
2,000 against homeowner associations for improper maintenance.21
21
Source: Toxlaw.com
12
Table 1
Mold Claims
State by State Breakdown
First Party Insurance Claims Only
Alabama
Alaska
Arizona
Arkansas
California
Colorado
Connecticut
Delaware
District of Columbia
Florida
Georgia
Hawaii
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Louisiana
Maine
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
36
42
661
126
3087
98
122
48
8
1384
187
12
29
76
135
54
159
81
117
36
41
101
168
82
129
213
Montana
Nebraska
Nevada
New Hampshire
New Jersey
New Mexico
New York
North Carolina
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont
Virginia
Washington
West Virginia
Wisconsin
Wyoming
36
47
114
49
215
32
398
513
64
363
624
366
404
36
377
97
562
4097
164
38
95
115
8
24
19
Source: Policy Holders of America ___ 20??, pp. ?? - ??
13
Map 1
14
Map 2
15
Map 3
16
Mold is obviously not confined to the U.S. or North America.22 A recent study
conducted by the National Public Health Institute of Finland reported that in a random
sample of 310 homes, a moisture problem was observed in 52% of the homes and 27%
had a mold problem. Exposure to moisture and mold was significantly associated with
colds, sinusitis, bronchitis, and difficulties in concentration.
A study of homes in the Taipei areas by the College of Public Health at the
National Taiwan University also found moisture problems. Almost 37% of the homes
were classified with some type of dampness or water problem. The prevalence of
respiratory symptoms was consistently higher in homes that experienced mold or
moisture problems.
The previous discussion obviously shows that the mold infestation problem is real
and pervasive and affects people across the globe. While the health effects to humans
have already been documented, there are also structural problems caused by mold.
VI. Mold and Structural Integrity Issues
Can mold cause structural damage to buildings? In most cases, mold is not the
immediate cause of the property damage. It is moisture intrusion that is the principal
cause of structural damage, whether it is due to undetected leakages or wind driven rains,
as is common in hurricanes and tornadoes. When moisture problems go undetected or
are not repaired quickly, the result is usually mold. Most mold related property damage
is to drywall, flooring, carpeting, clothing, and books. However, if mold infestation is
prolonged and extensive, remediation may involve removal and replacement of large
17
parts of the structure. Some of the mold related lawsuits have resulted in judgments for
repairs well in excess of $1 million.23
Mold appears to be an equal opportunity infiltrator and has been found in homes,
apartments, schools, churches, and commercial buildings. Since the presence of moisture
is a prerequisite for mold growth, structures that are more prone to water intrusion, and in
particular, trapping moisture once inside, are more likely to have mold problems. Homes
clad in synthetic stucco (EIFS) or foam backed vinyl siding have been cited by a number
of sources24 as being more susceptible to mold problems since such siding can trap
moisture inside buildings. Although no hard evidence is available to support such claims,
given the close association of mold and moisture intrusion problems, such a linkage
would not be surprising.
There is a mold related problem, however, that may have more far reaching
consequences with respect to the structural integrity of homes. Although not generally
included under the rubric of toxic or harmful mold, there are other types of fungi that
attack wood that can threaten the soundness of dwellings. There are several types of
fungi that feed on the cellulose in wood, which if left unchecked, can ultimately destroy a
building. Brown Rot, sometimes incorrectly called “dry rot”, will cause wood to lose its
strength, crack, and when dry, turn to powder.25 Another fungal variety, White Rot, will
cause wood to shrink, become spongy, and when severely degraded, collapse. What
these fungi and molds have in common is that they all need moisture to grow.
22
Source: The National Library of Medicine
We need a source for this or delete statement.
24
http:// money.cnn.com/2000/03/24/home; www.bbjchem.com/new, 12/03/99;
http://fly.hiwaay.net/bayless/vinyl
25
Old infestations of brown rot which have dried out are commonly referred to as dry rot.
23
18
Most wood decaying fungi can only grow on moist wood and cannot attack
nearby wood structures if they remain dry. However, certain types of brown rot,
sometimes called water-conducting fungi can also attack dry wood, and, therefore, cause
much more extensive damage. It differs from other types of wood destroying fungi
because it can conduct water over large areas through root-like structures called
rhizomorphs, thereby supporting additional decay. As long as a supply of moisture is
available, this type of fungus can spread to an entire structure. The North Carolina State
University’s Department of Entomology reports such fungi can cause extensive damage
within 2 to three years.26
The most common form of water-conducting fungus in meruliaporia incrassate,
known more simply as “Poria.” While this fungus is largely contained to the Southern
and the Gulf States, it has also been found in parts of California.27 Interestingly, it is
found most commonly in new or remodeled houses and sometimes mistaken as
subterranean termite damage. Experts have speculated that the soils used in landscaping
or under room additions may have originated in forests which contain poria where it
naturally helps in the decomposition process.28 There may also be a link between EIFS
homes and wood destroying fungus.29 Fortunately, as will be seen in the next section of
this report, wood destroying fungi can be eliminated in the same way that mold can be
destroyed.
VII. Remedial Action
Insect Note ENT/rsc-23 (2000). See also “Decay Fungi” at www.pestproducts.com/decayfungi.htm
Cite NC study
27
See www.moldremoval.com/html/Fungi/meruliaporia_incrasata.htm
28
Wayne Wilcox, UC Berkeley Professor of Forestry stated he found that in many houses the onset of poria
occurred within 2 years of major landscaping work. See the website in footnote 3.
29
See Richard Thompson’s article “How to Fight Dryrot in Homes, Condos and Co-ops” in Realty Times
at realtytimes.com/rtnrews/rtcpages/20010103_dryrot.htm.
26
19
The specific actions that should be taken when dealing with mold largely depend
upon the type of mold, the source(s) of the mold, and how large an area has been
infiltrated by the mold. Wet mold requires different remediation techniques than if the
problem is mold spores or mycotoxins. Once the source(s) of the mold infiltration is
ascertained, then its removal can begin. The next question is much more difficult to
answer. Once a mold problem is discovered, how much remediation is necessary? Stated
differently, are there safe levels of mold? Unfortunately, as yet no scientifically
determined standards or safe tolerance levels have been established for exposure to
molds. Neither the CDC nor the EPA has announced safe threshold levels for airborne
mold, nor do specific federal government guidelines exist for evaluating the potential
health risks of mold. Recent legislation enacted in California, the Toxic Mold Disclosure
Act of 2001, directs the California Department of Health Services to consider adopting, if
feasible, exposure limits for toxic mold and remediation guidelines. Until such standards
are established, whether in California by the CDHS or otherwise, it may be very difficult
to know how much remediation is necessary or when the job is done. Unfortunately, the
CDHS is not due to make a progress report until July 1, 2003.
Testing recommendations run the gamut from simple visual inspections and
cleanup procedures to the use of certified environmental inspectors and laboratory testing
of mold samples, while remediation can involve sealing off contaminated areas,
evacuation of the premises, and the actual destruction of the contaminated property.
Because of all the media attention, there is a heightened sense of awareness among the
general public, which has sometimes resulted in an over-reaction to mold related
problems, and the consequent use of unnecessary and excessively expensive remedial
20
procedures. On the other hand, people, especially those with compromised immune
systems, should not underestimate the potential health hazards associated with mold. The
goal of this section of the report is to develop a reasonable approach to both inspection
and fungal remediation that is based upon accepted scientific evidence and procedures.
Inspections
The remediation process generally starts when evidence of mold is discovered,
either as a result of a physical inspection of the property, a musty odor is detected, or
when residents or workers exhibit mold related symptoms. Since most mold problems
involve the presence of moisture, mold is most often discovered by occupants, repairmen,
or insurance adjusters when the property sustains water damage. In some cases, mold
growth is not obvious or detectable through a casual inspection of the property. Mold can
be growing on hidden surfaces or locations such the backside of drywall, behind
wallpaper, under ceiling and floor tiles, under carpets or in the sub-flooring of a structure.
Ventilation systems should also be visually inspected for damp conditions, with special
attention given to system filters.
If the mold is visible and the area infected is small and occupants are not suffering
from health problems, a properly trained insurance adjuster and a remediation contractor
can generally solve the problem quickly. Here we are not talking about very small clean
up problems associated with mildew, other common household fungi, or even infestations
of Stachybotrys, which can easily be eliminated by homeowners with a mixture of bleach
21
and water or a household fungicide.30 Generally, mold does not present a serious clean up
problem until it reaches approximately 2 square feet in size.31
Neither the California Department of Health Services nor the Minnesota
Department of Health recommend testing to determine the type or strain of mold, at least
as a first step in determining whether you have a mold problem. The Minnesota
Department of Health states that testing should never take the place of visual inspection
and should not use up resources needed to correct the moisture problem and remove the
mold. If mold is visible or you detect a musty odor, you probably have a mold problem.
The first step is to kill the mold. However, if occupants or residents are experiencing
physical or neurological symptoms which may be related to fungal exposure, it may be
necessary to determine what type and species of mold are present and whether they are
harmful. Generally, this means hiring an environmental professional, such as a certified
industrial hygienist (CIH)32, or testing lab to test the mold. Such testing, depending on
the methods used, can be very costly as well as time consuming and many insurance
companies may not cover the cost.33 Such testing can often be conducted concurrently
with the clean up, as time is an important factor when it comes to mold remediation.
Once moisture is present, it doesn’t take long for mold to begin growing, usually within
24 to 48 hours. Here, however, it is important to make sure that such repairs are
approved by the property insurer and do not void the policy. This issue will be addressed
in more detail in a later section of this study.
30
In many cases homeowners never realize that toxic mold is present because they clean up before the
mold has a chance to grow large enough to present a hazard.
31
“Truth Told on Toxic Mold” by John Wagner. See www.todayshomeowner.com/repair/10080211.digest1
32
For more information about certified industrial hygienists visit the website of the American Board of
Industrial Hygiene at www.abih.org. In Texas, the state department of health maintains a list of certified
indoor air consultants. See the website, www.tdh.state.tx.us/beh/iaq/.
22
Testing a structure for mold generally involve taking swabs, air samples and tape
lifts of the mold which are then sent to a lab where samples can be cultured and the type
of mold identified. In some cases contaminated portions of the structure will have to be
removed (bulk sampling) and sent to a lab for testing. Where the source of the mold
cannot be determined or when multiple sources of mold may be present, wall cavity
samples may have to be taken. This involves employing a moisture meter to locate
possible areas of high moisture or water intrusion. Holes will then be drilled into the
walls at these locations and air samples taken from behind the walls. A boroscope can be
used to view spaces inside ductwork and behind walls. The critical part of the inspection
and testing process is to make sure that other parts of the structure are not contaminated.
When mold is detected it is also very important that the testing procedures allow for the
determination of which species of mold is present, as some forms of a given mold can be
more harmful than other strains of the same mold.
As the New York City remediation guidelines34 point out, air sampling for fungi
should not be part of a routine inspection unless occupants have been diagnosed with
an illness that is associated with fungal exposure. Air monitoring may be called for,
however, in cases where mold is suspected, but cannot be identified by visual or bulk
sampling methods. Air sampling may also be necessary if there is evidence that the
building’s ventilation systems may be contaminated.
When air sampling is conducted, both indoor and outdoor samples must be
performed so a baseline can be determined. In general, the levels and types of fungi
33
It is even possible to buy a self-testing kit (www.moldtestkit.com) with which you can take samples
which are then sent off to a lab for testing. See www.homehealthscience.com for more information.
34
“Guidelines on Assessment and Redmediation of Fungi in Indoor Environments,” New York City
Department of Health, Bureau of Environmental & Occupational Disease Epidemiology, 2000.
23
found inside and outside the property should be similar for non-problem buildings. If
spore counts within a structure are appreciably higher than outdoors, the property
probably has a mold problem.35
Remediation
Once the mold is located (and typed, if necessary) remediation can proceed.
Although there are no universally acceptable standards for containment and remediation,
the most commonly relied upon are the guidelines developed by the New York City
Department of Health and the Bureau of Environmental & Occupational Disease
Epidemiology and referenced above. These guidelines establish four levels of
contamination based upon the square footage involved, which, in turn, dictates the
remediation strategy. There is an additional set of guidelines, level 5, for HVAC
systems.
Level 1 refers to small areas of isolated contamination of 10 square feet or less.
This could involve small sections of mold covered ceiling tiles or a small section of wall.
For level 1 contamination, remediation can be performed by a remediation contractor or
properly trained building maintenance staff people employed by schools, offices, and
other businesses.36 Workers should wear respirators, gloves, and eye protection.
Isolation or containment of the clean up area is usually not necessary so long as
appropriate dust suppression methods (misting) are employed. Non-porous materials
(glass, metals, and hard plastics) can be cleaned and reused. Contaminated porous
materials (wallboard, insulation) that cannot be cleaned should be removed from the
For more information on air sampling see “Bioaerosols: Assessment and Control”, by the American
Conference of Governmental Industrial Hygienists.
36
Trained employees, as referred to by the New York guidelines, refer to individuals whose training
complies with OSHA Hazard Communication Standard (29 CFR 1910.1200).
35
24
building in sealed plastic bags. Work areas used by cleanup workers should be cleaned
with a damp cloth or mop and a detergent solution.
Level 2 contamination covers mid-sized isolated areas between 10 and 30 square
feet. Insurance sources (Carpenter) indicate that the most common mold claims are for 30
square feet or less of visible contamination. In addition to the recommendations already
included for Level 1 contamination, Level 2 guidelines include two more. The work
area should be covered with plastic sheeting and sealed with tape before remediation
work begins. Second, the work area and the areas used by work crews should be cleaned
with vacuums equipped with High-Efficiency Particulate Air filters.
Not surprisingly, the greater the contamination problem, the more extensive and
costly the mold elimination procedures. Level 3 refers to large isolated areas of mold
between 30 and 100 square feet, while Level 4 refers to extensive mold contamination of
greater than 100 square feet.
With problems this severe consultation with health and safety professionals,
experienced in performing microbial investigations, is needed to determine appropriate
remediation procedures and oversee cleanup activities. Personnel trained in the removal
of hazardous material, supplied with the appropriate OSHA approved protective gear, not
building maintenance people, should be employed. At a minimum, contaminated areas
should be completely isolated, and, depending upon the level of contamination,
ventilation systems may have to be sealed, the use of exhaust fans with HEPA filters may
be needed to produce negative pressurization within the structure, and in the worst case
scenario, the property may have to be vacated by occupants during the cleanup. When
25
HVAC systems are contaminated, air monitoring will usually be necessary and biocides
may have to be introduced into HVAC system components.37
How do you know when the job is finished? As the EPA points out this is
ultimately a judgment call. The EPA does, however, offer some recommendations. First,
the moisture problem must be corrected, and as can best be determined, mold removal
must be complete; visible mold and musty odors should no longer be present. If air
samples have been taken, the types and concentrations of mold spores found in the
building should be similar to those found outside. Once the cleanup has been completed,
fungal related symptoms should not recur after the property is re-occupied. Periodic reinspection of the property should also be undertaken to insure the mold problem has not
returned.
Summary
In the absence of scientifically verified safe exposure levels, prompt remediation
and repair of damaged structural components is the best response when mold or fungal
contamination is discovered. Since mold can grow so fast, the moisture source feeding
the mold must be identified and the problem corrected as soon as possible. Once the
extent of the contamination is determined the simplest and least costly removal
techniques most appropriate to the scale of the problem should be employed. Since most
mold contamination in homes and businesses involve small, relatively isolated areas, less
than 30 square feet in size, homeowners, mold abatement contractors, and building
maintenance people can usually handle the problem at relatively low cost. Testing costs
can range from under $100 for self-testing kits to between $1,000 and $4,000 for
37
This discussion is not meant to be an exhaustive treatment of remediation procedures. See the New York
City Guidelines and “Mold Remediation in Schools and Commercial Buildings” by the EPA for more
26
industrial hygienist’s reports, including testing and lab work.38 The New York City
guideline’s estimate the removal of visible mold costs $150 per square foot.39 Relatively
small clean up jobs can usually be handled by remediation contractors. Costs will
obviously be much higher when construction flaws and structural damage are involved.
However, in cases of widespread contamination, much more expensive and extensive
testing and removal procedures are typically required. In such situations consultations
with health and safety specialists are necessary before appropriate remediation strategies
can be determined and implemented.
VIII. Mold Prevention
We already know that water or high humidity levels, nutrients, and the right
temperatures are required for mold growth. Therefore, no matter the specific and detailed
prevention recommendations, the ultimate objectives are to eliminate the conditions that
allow mold to propagate. There is no way to prevent mold and their spores from entering
structures. By maintaining a clean, dry home or workplace, dangerous molds cannot
begin to grow. That said, what, specifically, can be done to prevent mold from taking
hold in our homes, schools, and places of business? The starting point is to identify the
various ways mold can infiltrate structures.
General Prevention Recommendations
The general recommendations that follow have been taken from multiple sources,
including the EPA, the CDC, Kansas State University, the Minnesota Department of
detailed information on this subject.
38
www.homehealthscience.com; “Reinsurance Perspectives” by Harry Zimmer in Toxic Mold: A Growing
Risk? Excerpts of Seminar Presentations Made on the Subject of Mold and Mildew, Guy Carpenter and
Company, 2001.
27
Health, and the California Department of Health Services and apply to all structures,
homes, offices, and schools. Mold prevention publications and recommendations for
specific types of property can obtained from the sources cited above as well as at the EPA
website, www.epa.gov/iaq/pubs/moldresources.

Eliminate moisture sources. Fix leaks in plumbing and make sure water is not
entering the home from the outside, caused by a leaking roof, cracks in
exterior siding, or inadequate calking around windows. Keep humidity levels
within homes below 50 percent. When relative humidity levels rise above
50% it is considered a water source. Use a dehumidifier if necessary.
Humidity levels can be measured by hygrometers, which can be purchased at
local hardware stores and other retail establishments. Seal cracks in basement
walls and foundations, and use downspouts to direct water away from
structures.

Make sure the building has adequate ventilation by installing exhaust fans in
bathrooms and kitchens, if not already present. Install ceiling fans. Open
doors between rooms. Move furniture away from walls and corners to
promote air circulation. Put a plastic cover over dirt in crawlspaces and make
sure they are well ventilated.

Keep drip pans in air conditioners, refrigerators, and dehumidifiers clean and
dry.

Do not carpet bathrooms and kitchens or other areas where water or high
levels of humidity are often present.
39
Guidelines on Remediation of Fungi in Indoor Environments.
28

If a water leak or flooding does occur, dry the effected areas as soon as
possible. It may be necessary to remove and replace water-damaged
carpeting. In some cases, hardwood floors and sub-flooring may have to be
replaced.

Clean bathrooms with fungicides or mold killing products.

When building materials need to be replaced, use non-cellulose and low
nitrogen replacement materials when possible. Doing so will remove food
sources from the structure.

Keep landscape sprinklers from soaking building exteriors and foundations.

Decrease the likelihood of moisture build up through condensation by raising
the temperature of cold surfaces by adding insulation and installing storm or
double-paned windows.

Add mold inhibitors or fungicides to paint.
Some recent reports contend that some of the mold problems now being
encountered may be related to the way homes are being built and the materials used in
construction.40 As noted earlier, vinyl siding, exterior insulation and finish systems, also
known as EIFS or synthetic stucco, and certain types of laminate sidings have been cited
as contributing to the mold problems now being increasingly encountered by
homeowners.
If EIFS is not installed properly, water can become trapped behind the siding.
Since EIFS is impermeable to moisture, once water breaches the building envelope, it
does not evaporate. Similar moisture problems have been noted with vinyl siding that
40
Source ?
29
use a foam backing. Not only can this lead to serious structural damage, but it also
creates an environment particularly conducive to mold infiltration and growth. All
sources of water entry must be identified, repaired, taped or caulked, and moisture must
be directed away from likely entry sites with flashing.
Vinyl wallpaper has been blamed for trapping moisture in the home, while the
glues used to affix wallpaper have been mentioned as nutrients supporting mold growth.
Even air conditioning, if oversized for the job at hand, can contribute to mold formation;
they quickly lower inside temperatures, but do not operate long enough to extract much
moisture from the air.
Building Code Considerations
As this report has repeatedly pointed out, moisture is the essential requirement for
mold growth. Add a warm climate and a food source and the result is mold. If, as the
previous discussion has pointed out, building methods and the construction materials can
contribute to the problem, serious consideration should be given to modifying building
codes to better withstand mold infiltration. Building code organizations, manufacturers,
insurance companies, state insurance commissions and legislatures are all paying
increasing attention to this issue.
Currently, there are three model building codes – the Uniform Building Code, the
Southern Standard Building Code, and the International Building Code. All three codes
are moving to one universally accepted code called the International Residential Code.
This code was recently adopted by the Texas legislature, which had earlier adopted the
Texas Windstorm Insurance Association Building Code in 1993.
30
Although primarily concerned with limiting damage from hurricanes along the
Texas coast, construction requirements that deter water intrusion and limit damage from
high winds can also make it more difficult for mold to get a foothold within buildings.
To satisfy these stricter standards shingles must be fastened with a minimum of 6 nails as
compared to 4 nails as is common practice, heavier felt under roofs, additional roofing
cement, and corrosion resistant fasteners must be used.
Although we have not been able to find any cost-benefit comparisons it seems
reasonable that the use of mold prevention materials and building techniques during
construction may prove more cost effective than remediation after a moisture problem is
discovered. Some recommendations41 that have been suggested include:

The use of vapor or moisture wraps that help seal the joints of structural wall
sheathing and the intersection points of the roof and walls.

Adhesive-backed moisture barrier tape to seal the edges of window frames and
doors to limit water intrusion from wind driven rain.

The use of “weep holes” with brick veneer to assist in dissipating moisture that
can collect between exterior and interior walls.

The use of corrosion resistant screws instead of nails to provide better anchorage,
when fastening roof decking and sheathing to rafters.
The Kansas State University Agricultural Experiment Station and Cooperative
Extension Service have developed an extremely useful guide to both mold remediation
and prevention. Entitled “Controlling Mold Growth in the Home”, it details specific
41
These recommendations have been taken from written excerpts of a Guy Carpenter & Co. seminar
presentation by Alexis Dick, Deputy Commissioner of Inspections of the Texas Department of Insurance.
31
recommendations for specific parts of the home and home components, including
clothing, and books. It is reproduced in the appendix to this study.
While many of these recommendations have to be assessed from a cost-effectiveness
perspective, and some of the above-mentioned methodologies are currently being tested,
enforcement of existing building codes can also improve moisture management.
Mold Disclosure
One obvious way to prevent mold is to avoid buying or renting a home or
building that already has a potential mold problem. Prospective buyers and tenants must
be on the alert for the presence of mold in the properties they are considering buying or
leasing. This is easier said than done. The problem here is that unless buyers know
about the harmful effects of mold they will not know to look for it. If mold is
subsequently discovered, insurance claims and lawsuits result. The substantial increase
in the number of lawsuits filed by homeowners and tenants relating to mold problems
discovered after occupancy bears witness to the scale of the problem.42
As the general public has become more aware of the harmful effects of mold,
there have been increasing demands placed upon the home and building inspection
industry to include mold as part of the inspection process. Unfortunately, the demand for
mold inspections appears to exceed the supply of professional inspectors trained to detect
mold in buildings. Thus, the earlier admonition for potential homebuyers and tenants to
be on guard against mold remains true even as the home inspection industry expands and
fields more operatives.
Greater concern over the mold problem is also putting greater pressure on home
and property sellers, landlords, and property managers. Failure by property owners and
32
property managers to disclose the presence of known mold problems leaves them open to
lawsuits by buyers and tenants. Real estate brokers may also be exposed to legal liability
when assisting in the purchase or sale of such properties. Since mold would constitute a
material fact, failure to disclose such information, if known by a real estate licensee,
could put the licensee in legal jeopardy. So far, we have found only two mold cases, one
in Arizona and the other in Pennsylvania, involving real estate licensees. 43 Both cases
have not yet been settled.
In the Arizona case, a homebuyer is suing a listing agent after discovering mold in
a newly purchased home. Prior to closing the seller offered to provide the buyer with an
inspection report paid for by the previous owner. Interestingly, the buyer was
represented by her own agent who did not recommend a new inspection. When the
insurance company denied her claim she sued the listing agent.
In the Pennsylvania case, the homebuyers are suing the sellers and the listing
agent for $660,000 for failure to disclose a water problem. The lawsuit alleges that mold
from the water damage caused the buyers to suffer severe allergic reactions that required
hospitalization. In their defense the sellers claim that the buyers declined an
environmental inspection.
While the vast majority of mold related lawsuits do not involve real estate
salespeople, the staggering increase in the number of mold cases and the magnitude of
some of the judgments and jury awards should give real estate professionals pause.
So far only one state, California, has mandated disclosure for mold problems.
The California State legislature, with the approval of the California Association of
42
We need a source for this or delete statement.
33
Realtors, has adopted two pieces of legislation, Senate Bill 732 and the Assembly Bill
284.
Assembly bill 284 directs the California Research Bureau to study fungal
contamination and remediation methods and report its finding by January 1, 2003. The
more important legislation is Senate Bill 372, called the Toxic Mold Protection Act of
2001. As mentioned earlier in this study, this bill directs the California Department of
Health Services to consider adopting, if feasible, standards for assessing the health risks
posed by indoor mold and establish permissible exposure limits for toxic mold. The
CDHS must provide the legislature with a progress report by July 1, 2003A new section
addressing mold was also added to the state’s existing environmental hazards booklet,
“Environmental Hazards: A Guide for Homeowners, Homebuyers, Landlords, and
Tenants.”
Equally important, Senate Bill 732 creates additional disclosure requirements for
sellers and lessors of real estate that include, in addition to other hazards, mold.44 These
disclosure requirements are directed primarily at the residential market, as they are
limited to residential properties and cooperatives of one to four dwelling units. However,
if the CDHS adopts permissible mold exposure limits, residential, commercial, and
industrial landlords will be required to provide current and prospective tenants with
written mold disclosure statements.
Although not legally mandated, the legislation does encourage real estate brokers
and salespeople to give prospective buyers and tenants the newly revised environmental
See the article “Mold in the Home: How it Affects Realtors” by Jill Freudenwald at
www.realtor.org/gapublic.nsf/pages/moldpapers, February, 2002.
44
The new law amends the Real Estate Transfer Disclosure Statement to specifically include mold. See
CAR’s Legal Q&A, “Mold and its Impact on Real Estate Transactions>”
43
34
hazards booklet. The statute provides that doing so constitutes adequate disclosure by
real estate professionals of those conditions described in the booklet, which now include
mold. In addition, as noted, the seller disclosure form that must be used in California was
revised as of January 1, 2002, to include a question about mold.
The California Association of Realtors publishes a booklet entitled “Buyer’s
Inspection Advisory” that states the agents do not have expertise in hazardous substances
and advises buyers to inspect the properties they are purchasing for, among other things,
environmental hazards such as mold. This document is attached to all purchase
agreements published by C.A.R.
Many other states have also passed mandatory seller disclosure statutes, while
Realtor associations in other locations have developed uniform seller disclosure forms
that, though not mandatory, encourage home sellers to complete and sign. To the best of
our knowledge, however, no other state has yet followed California’s lead by specifically
including mold in their seller disclosure forms.
IX. Insurance Issues
The very recent, but incredible proliferation of insurance claims related to indoor
mold problems represents a serious, and possibly catastrophic, problem for casualty
companies. Farmers Insurance, with 7% of the U.S. homeowner’s insurance market,
estimates that mold claims in 2001 will cost the company $85 million.45 It has been
45
Source ?
35
estimated that investigating a mold claim, covering living expenses of displaced owners,
and paying for cleanup and mold remediation costs an average of $30,000 per claim.46
The response by the insurance industry is to try and limit coverage by eliminating
mold coverage from the basic homeowner’s policy. Because of the staggering increase in
claims in Texas, the state’s largest insurers, Allstate, Farmers, and State Farm, have
stopped selling comprehensive policies.47 In November 2001 the Texas State Insurance
Commissioner sharply restricted mold coverage for Texas homeowners.
The order limits coverage for the removal of mold to cases of “sudden and
accidental discharge, leakage or overflow of water” so long as water damage is otherwise
covered in the policy. “Sudden and accidental” is defined to include a physical loss that
is hidden or concealed for a period of time until it is detectable. A hidden loss must be
reported to the insurance company within 30 days of the date that the homeowner detects
or should have detected the loss.
This suggests, for example, that if mold damage results from a roof damaged
during a storm and the damage is reported in a timely manner to the insurer, the
policyholder is covered. However, if the leak is caused by normal wear and tear, or if the
homeowner knows about the leak and does nothing about repairs, the policy will not
cover the resulting loss.
The order also eliminates coverage for testing, treating, containing, or disposing
of mold beyond what is necessary to repair or replace the property that is physically
damaged by water. Homeowners who want more comprehensive mold coverage will
have to pay higher premiums.
46
47
Source: The Texas Department of Insurance as reported in Tierra Grande, Vol. 8, No. 4, October 2001.
Source ?
36
The Texas State Insurance Commission is in the difficult position of trying to
preserve mold coverage for consumers at a reasonable cost and at the same time not
bankrupt the insurance industry. It has been estimated that comprehensive mold
coverage could raise insurance premiums by as much as 40 percent.48
Certainly a case can be made that insurance policies are not maintenance
agreements, and policyholders should not be forced to subsidize homeowners who do not
maintain their homes. However, policyholders are left in an ambiguous position with
respect to what constitutes a “sudden and accidental” and “detectable” loss and faced
with higher insurance premiums for more extensive mold coverage.
These are issues that insurance commissions and legislatures in other states are
now or will soon have to deal with. It may well be the case that the true limits of mold
coverage will ultimately have to be determined by the courts.
What should homeowners do when a water or mold problem is discovered? It is
obviously important to notify the insurance carrier immediately so that cleanup can begin
as soon as possible. As already pointed out, the longer a moisture problem exists the
greater the likelihood and severity of mold infestation. The insurance company, for its
part, must send an adjuster as soon as possible once notified about the problem, and begin
repairs as soon as possible. Failure to do so could constitute a breach of faith with the
insured and result in litigation. The $32 million jury award to Melinda Ballard was based
upon the charge that the insurance company delayed repairs, thereby creating an even
greater mold problem and endangering the health of the occupants.49
48
49
Ibid.
Source ?
37
One of the problems encountered by homeowners filing claims is that repairing a
water intrusion problem before the insurance company signs off on the repair may void
the claim. There have been reports that some insurance companies have been slow to
respond to mold claims. In part, this may be do to the fact that claims of mold infestation
are a relatively recent phenomenon and insurance do not as yet have enough trained
adjusters to handle the work load. Whatever, the reason, it is incumbent upon both the
homeowner and the insurance company to act responsibly and quickly when a mold
problem is discovered.
In light of all these actual and potential changes taking place within the insurance
industry it is very important that homeowners, whether in Texas or elsewhere, look
carefully at their insurance policies to make sure that mold damage coverage is not
specifically excluded. With some insurance policies the issue is whether or not the
damage was caused by mold or the mold was the result of another cause that is covered
by the policy. If a covered peril is the proximate cause of the mold, the resulting damage
is covered. Stated differently, the deciding issue is whether the mold is a cause or an
effect.
Because of the ambiguity surrounding this issue some carriers are attempting to
include fungus exclusionary provisions in their policies that deny mold damage claims
whether they occur naturally or because of an otherwise covered peril. Consumers must,
therefore, compare and scrutinize homeowner policies closely to make sure they do not
contain unwanted mold exclusions or other provisions that could limit the coverage they
seek in the event of moisture and mold damage.
38
X. Summary and Conclusions
As this study has tried to document, the problem of mold, even though we still
do not know for certain just how pervasive, how hazardous, or how costly it may
become, requires our immediate attention. Failure to address this problem now only
puts home and property owners, and the people and institutions that serve them at even
greater risk for loss in the future. Insurance companies, real estate brokers, landlords
and property managers, home inspection services, consumers, and virtually all other
real estate market participants need to be proactive when dealing with mold related
problems. The best defense is prevention.
The first step involves learning about the nature of the mold problem and its
causes. The information presented in this report strongly suggests that mold is
responsible for most allergies, asthma, and other respiratory illnesses, and has been
linked to even more serious health problems. Homeowners must undertake regular
home maintenance inspections and be on guard against water leaks, musty odors, and
other telltale signs of mold infestation. When indoor mold is detected, appropriate
cleanup should begin immediately. Insurance companies must respond quickly to
claims of water intrusion and correct the problem before mold has a chance to gain a
foothold, thereby avoiding even more serious and costly damage. Real estate brokers
and salespeople must alert homebuyers and sellers to the risks and causes of mold,
recommending moisture and mold inspections as a prerequisite to a purchase.
Government officials, at both the state and national levels, also have roles to play.
Mandatory seller disclosure that includes mold is already in place in California, and it
39
would not be surprising to see other states follow California’s example. Various federal
government agencies such as the CDC and the EPA have issued mold prevention and
remediation guidelines as well as consumer information booklets. The U.S Department
of Health and Human Services is currently sponsoring a study seeking to link damp
indoor environments with specific health problems.
If and when mold is discovered, following the remediation guidelines described in
this study will help determine the most cost effective clean up and repair modalities. For
the real estate professional, learning more about the nature and causes of mold will help
them better service the consumer and implement appropriate risk reduction procedures.
40
Appendix A
Specific Illnesses That Appear To Be Associated With Exposure To Mold
By
Suzanna Hartley
Resource Specialist
The Alabama Real Estate Research and Education Center
Allergies
The most common response to mold exposure may be allergy. People who are
genetically capable of producing an allergic response (atopic) may develop symptoms of
allergy when their respiratory system or skin is exposed to mold or mold products to
which they become sensitized.
Allergic reactions can range from mold, transitory responses, to severe chronic illnesses.
The Institute of Medicine (1993) estimates that one in five Americans suffers from
allergic rhinitis, the single most common chronic disease experienced by humans. About
14% of the U.S. population suffers from allergy-related sinusitis and 10-12% have
allergy-related asthma. About 9% of the U.S. population suffers from allergic dermatitis
and less than 1% suffer from serious chronic allergic diseases such as allergic
bronchopulmonary aspergillosis (ABPA) and hypersensitivity pnueumonitis (Institute of
Medicine, 1993). Allergic fungal sinusitis is a common illness among atopic individuals
living and working in moldy environments. There is a question as to whether this illness
is solely allergic or has an infection component. Molds are just one source of indoor
allergens, including dust mites, effluvia from domestic pets, cockroaches, and
microorganisms (including molds).
Thousands of different molds can contaminate indoor air, but purified allergens have
been recovered from just a few of them. This means that those people who are atopic
may be exposed to indoor molds and develop sensitization, yet may not be diagnosed as
having a mold allergy. Allergy tests performed by physicians involve the confrontation
between and individual’s immune system and the introduction of mold allergens.
Because the reaction is highly specific, it is possible that even closely related mold
species may cause allergy, yet that allergy may not be detected through challenge with
the few purified mold allergens available for allergy tests (Ammann, 2001). A positive
mold allergy test indicates sensitization to an antigen contained in the test allergen while
a negative test does not rule out mold allergy for atopic individuals.
Infection
41
Infection from molds that grow indoors is not a common occurrence, except in specific
susceptible populations, such as those with compromised immune systems from disease
or drug treatments. A number of Aspergillus species that can grow indoors are known to
be a specific cause of disease or pathogen. Aspergillus fumigatus (A. fumigatus) is a
weak pathogen that is thought to cause infections called aspergilloses in susceptible
individuals. It is known to be a source of nosocomial infections among immune
compromised individuals. These infections affect the skin, eyes, lungs, and other organs
and systems. A. fumigatus is fairly commonly implicated in ABPA and allergic fungal
sinusitis. Aspergillus flavus has also been found as a source of nosocomial infections
(Gravesen et al., 1994). There are also other fungi that cause systemic infections such as
Coccodiodes, Histoplasma, and Blastomyces. These fungi grow in soils and can also be
transported by birds and bats, and do not typically grow in indoor environments. Their
occurrence is connected to exposure by wind-born or animal-born contamination.
Mucous Membrane and Trigeminal Nerve Irritation
A third group of potential health effects from fungal exposure comes from the volatile
compounds (VOC) produced through fungal primary or secondary metabolism, and
released into the indoor air. Some of these volatile compounds are produced continually
as the fungus consumes more and more of its food source during primary metabolic
processes (Primary metabolic processes are those necessary to sustain an individual
organism’s life, including energy extraction from foods, and the syntheses of structural
and functional molecules such as proteins, nucleic acids and lipids) (Ammann, 2001).
Depending on the available oxygen, fungi may engage in wither aerobic or anaerobic
metabolism. They may produce alcohols or aldehydes and acidic molecules. Such
compounds in low but sufficient aggregate concentration can irritate the mucous
membranes of the eyes and respiratory system.
The nature of the food source on which a fungus grows can result in particularly pungent
or unpleasant primary metabolic products. Certain fungi can release highly toxic gases
from the substrate on which they grow. For instance, one fungus growing on wallpaper
released the highly toxic gas arsine from arsenic containing pigments (Gravesen, et al.,
1994).
Fungi can also produce secondary metabolites as needed. These are not produced all the
time because they require extra energy from the organism. These secondary metabolites
are the compounds that are typically referred to as a “moldy” or “musty” odor associated
with growing mold. However, compounds such as piene and limonene that are used as
solvents and cleaning agents can also have a fungal source. Depending on the
concentration of this fungus, these compounds are considered to have a “clean” or
“pleasant” odor by some individuals. Fungal volatile secondary metabolites are give
flavors and odors to many foods. Some of these are found in cheese. The production of
some compounds is closely related to sporulation of the organism. “Off” tastes may be
correlated to selective advantage to the survival of the fungus if not to the consumer.
42
In addition to mucous membrane irritation, fungal volatile compounds may affect the
“common chemical sense” which senses pungency and responds to it. This sense is
primarily associated with the trigeminal nerve (and to a lesser extent the vagus nerve).
This mixed (sensory and motor) nerve responds to pungency, not odor, by initiating
avoidance reactions, including breath holding, discomfort, or odd sensations, such as
itching, burning, and skin crawling. Changes in sensation, swelling of mucous
membranes, constriction of respiratory smooth muscle, or dilation of surface blood
vessels may be part of fight or flight reactions in response to trigeminal nerve stimulation
(Ammann, 2001). Decreased attention, disorientation, diminished reflex time, dizziness
and other effects can also result from such exposures (Otto et al., 1989).
It is difficult to determine whether the level of volatile compounds produced by fungi
influence the total concentration of commons VOCs found indoors to any great extent. A
mold-contaminated building may have a significant contribution derived from its fungal
contaminants that is added to those VOCs emitted by building materials, paints, plastics,
and cleaners (Ammann, 2001). Miller and co-workers (1988) measured total VOC
concentration approaching the levels at which Otto et al., (1989) found in trigeminal
nerve effects.
At greater exposure levels, VOCs from any source are mucous membrane irritants, and
can have an effect on the central nervous system and produce such symptoms as
headache, attention deficit, inability to concentrate or dizziness.
Adverse Reactions to Odor
Odor produced by molds may also adversely affect some people. The ability to perceive
and respond to odors varies according to the individual. Some people can detect
extremely low concentrations of volatile compounds, while others need high levels for
awareness. Some people may respond to these odors with headaches, nausea or
vomiting. It is not known whether such responses are learned, or are time-dependent
sensitization of portions of the brain, perhaps mediated through the olfactory sense (Bell,
et all 1993a; Bell et al., 199b), or whether they serve a protection function. Asthmatics
may respond to odors with symptoms.
Toxicity
Mycotoxins are products of secondary metabolism of molds. They are not essential to
maintaining the life (obtaining energy or synthesizing structural components) of the mold
cell. They are products whose function seems to be to give molds a competitive
advantage over other mold species and bacteria. Mycotoxins are nearly all cytoxic,
disrupting various cellular structures such as membranes, and interfering with vital
cellular processes such as protein, RNA, and DNA synthesis. It goes without saying they
are also toxic to the cells of higher plants and animals, including humans.
43
Mycotoxins vary in specificity and potency for their target cells, cell structures or
processes by species and strain of the mold that produces them. Higher organisms are not
targets for mycotoxins, but rather caught in the crossfire of biochemical warfare among
mold species and molds and bacteria vying for the same ecological niche (Ammann,
2001).
Not all molds produce mycotoxins, but numerous species do (including some found
indoors in contaminated buildings). Toxigenic molds vary in their mycotoxin
productions depending on the substrate on which they grow (Jarvis, 1990). The spores,
with which the toxins are primarily associated, are cast off in blooms that vary with the
mold’s diurnal, seasonal and life cycle stage (Burge, 1990; Yang, 1995). The presence of
competitive organisms may play a role, as some molds grown in monoculture in the
laboratory lose their toxicity potency (Jarvis, 1995). Until relatively recently, mold
poisons were regarded with concern primarily as contaminants in foods (Ammann, 2001).
In Dr. Ammann’s discussion on the toxicity of mycotoxins she states that “It has come to
the attention of many that exposure to multiple mycotoxins from a mixture of mold
spores growing in wet indoor environments can cause health effects in many people.”
These health effects from multiple mycotoxin exposure can differ from those related to
single mycotoxin exposure in a controlled laboratory exposure. Indoor exposures to
toxigenic molds resemble field exposures of animals more closely than they do controlled
experimental laboratory exposures (Ammann, 2001). Animals in these controlled
laboratory exposures are healthy, of the same age, raised under the most select
conditions, and were exposed with a known dosage of a single toxic agent via a single
exposure route. In contrast, animals used in field exposures are in various stages of
health and age, possibly living in less than optimum environmental and nutritional
environments and are exposed to a mixture of toxic agents by multiple exposure routes.
Exposures to individual toxins may be much lower than those required to elicit an
adverse reaction in a small controlled exposure group of ten animals per dose group. The
effects from exposure may therefore not fit neatly into the description given for any
single toxin, or the effects from a particular species, of mold.
Field exposures of animals to molds (in contrast to controlled laboratory exposures) show
effects on the immune system as the lowest observed adverse effect. Such immune effects
are manifested in animals as increased susceptibility to infectious diseases (). It is
important to note that almost all mycotoxins have an immunosuppressive effect, although
the exact target within the immune system may differ. Many are also cytotoxic, so that
they have route of entry effects that may be damaging to the gut, the skin or the lung.
Such cytotoxicity may affect the physical defense mechanisms of the respiratory tract,
decreasing the ability of the airways to clear particulate contaminants (including bacteria
or viruses), or damage alveolar macrophages, thus preventing clearance of contaminants
from the deeper lung. The combined result of these activities is to increase the
susceptibility of the exposed person to infectious disease, and to reduce his defense
against other contaminants. They may also increase susceptibility to cancer
44
Because indoor samples are usually comprised of a mixture of molds and their spores, it
has been suggested that a general test for cytotoxicity be applied to a total indoor sample
to assess the potential for hazard as a rough assessment (Gareis, 1995).
The following summary of toxins and their targets provided by Dr. Harriet Ammann and
is adapted from Smith and Moss (1985), with a few additions from the more recent
literature. While this assemblage of effects does not describe the effects from multiple
exposures, which could include synergistic effects, it does provide possible results of
mycotoxin exposure to multiple molds indoors.
1. Vascular system (increased vascular fragility, hemorrhage into body tissues, or
from lung, e.g., aflatoxin, satratoxin, roridins).
2. Digestive system (diarrhea, vomiting, intestinal hemorrhage, liver effects, i.e.,
necrosis, fibrosis: aflatoxin; caustic effects on mucous membranes: T-2 toxin;
anorexia: vomitoxin.
3. Respiratory system: respiratory distress, bleeding from lungs e.g., trichothecenes.
4. Nervous system, tremors, incoordination, depression, headache, e.g., tremorgens,
trichothecenes.
5. Cutaneous system : rash, burning sensation sloughing of skin, photosensitization,
e.g., trichothecenes.
6. Urinary system, nephrotoxicity, e.g. ochratoxin, citrinin.
7. Reproductive system; infertility, changes in reproductive cycles, e.g. T-2 toxin,
zearalenone.
8. Immune system: changes or suppression: many mycotoxins.
It should be noted that not all mold have been tested for toxins, nor have all species
within a genus necessarily been tested. Conditions for toxin production varies with cell
and diurnal and seasonal cycles and substrate on which the mold grows, and those
conditions created for laboratory culture may differ from those the mold encounters in its
environment.
Toxicity can arise from exposure to mycotoxins via inhalation of mycotoxin-containing
mold spores or through skin contact with the toxigenic molds (Forgacs, 1972; Croft et al.,
1986; Kemppainen et al., 1988 -1989). A number of toxigenic molds have been found
during indoor air quality investigations in different parts of the world. Among the genera
most frequently found in numbers exceeding levels reached outdoors are Aspergillus,
Penicillium, Stachybotrys, and Cladosporium (Burge, 1986; Smith et al., 1992; Hirsh and
Sosman, 1976; Verhoeff et al., 1992; Miller et al., 1988; Gravesen et al., 1999).
Penicillium, Aspergillus and Stachybotrys toxicity, especially as it relates to indoor
exposures, will be discussed briefly in the paragraphs that follow.
Aspergillus
45
Aspergillus species are also fairly prevalent in problem buildings. This genus contains
several toxigenic species, among which the most important are, A. parasiticus, A. flavus,
and A. fumigatus. Aflatoxins produced by the first two species are among the most
extensively studied mycotoxins. They are among the most toxic substances known, being
acutely toxic to the liver, brain, kidneys and heart, and with chronic exposure, potent
carcinogens of the liver. They are also teratogenic (Smith and Moss, 1985; Burge, 1986).
Symptoms of acute aflatoxicosis are fever, vomiting, coma and convulsions (Smith and
Moss, 1985). A. flavus is found indoors in tropical and subtropical regions, and
occasionally in specific environments such as flowerpots. A. fumigatus has been found in
many indoor samples. A more common aspergillus species found in wet buildings is A.
versicolor, where it has been found growing on wallpaper, wooden floors, fibreboard and
other building material. A. versicolor does not produce aflatoxins, but does produce a less
potent toxin, sterigmatocystin, an aflatoxin precursor (Gravesen et al., 1994). While
symptoms of aflatoxin exposure through ingestion are well described, symptoms of
exposure such as might occur in most moderately contaminated buildings are not know,
but are undoubtedly less severe due to reduced exposure. However, the potent toxicity of
these agents advise that prudent prevention of exposures are warranted when levels of
aspergilli indoors exceed outdoor levels by any significant amount. A. fumigatus has
been found in many indoor samples. This mold is more often associated with the
infectious disease aspergillosis, but this species does produce poisons for which only
crude toxicity tests have been done (Betina, 1989). Recent work has found a number of
tremorgenic toxins in the conidia of this species (Land et al., 1994). A. ochraceus
produces ochratoxins (also produced by some penicillia as mentioned above).
Ochratoxins damage the kidney and are carcinogenic (Smith and Moss, 1985).
Stachybotrys chartarum (atra)
Stachybotrys chartarum (atra) has been much discussed in the popular press and has been
the subject of a number of building related illness investigations. It is a mold that is not
readily measured from air samples because its spores, when wet, are sticky and not easily
aerosolized. Because it does not compete well with other molds or bacteria, it is easily
overgrown in a sample, especially since it does not grow well on standard media (Jarvis,
1990). Its inability to compete may also result in its being killed off by other organisms in
the sample mixture. Thus, even if it is physically captured, it will not be viable and will
not be identified in culture, even though it is present in the environment and those who
breathe it can have toxic exposures. This organism has a high moisture requirement, so it
grows vigorously where moisture has accumulated from roof or wall leaks, or chronically
wet areas from plumbing leaks. It is often hidden within the building envelope. When S.
chartarum is found in an air sample, it should be searched out in walls or other hidden
spaces, where it is likely to be growing in abundance. This mold has a very low nitrogen
requirement, and can grow on wet hay and straw, paper, wallpaper, ceiling tiles, carpets,
insulation material (especially cellulose-based insulation). It also grows well when wet
filter paper is used as a capturing medium.
S. chartarum has a well-known history in Russia and the Ukraine, where it has killed
thousands of horses, which seem to be especially susceptible to its toxins. These toxins
46
are macrocyclic trichothecenes. They cause lesions of the skin and gastrointestinal tract,
and interfere with blood cell formation. (Sorenson, 1993). Persons handling material
heavily contaminated with this mold describe symptoms of cough, rhinitis, burning
sensations of the mouth and nasal passages and cutaneous irritation at the point of
contact, especially in areas of heavy perspiration, such as the armpits or the scrotum
(Andrassy et al., 1979).
One case study of toxicosis associated with macrocyclic trichothecenes produced by S.
chartarum in an indoor exposure, has been published (Croft et al., 1986), and has proven
seminal in further investigations for toxic effects from molds found indoors. In this
exposure of a family in a home with water damage from a leaky roof complaints included
(variably among family members and a maid) headaches, sore throats, hair loss, flu
symptoms, diarrhea, fatigue, dermatitis, general malaise, and depression. (Croft et al,
1986; Jarvis, 1995).
Johanning, (1996) in an epidemiological and immunological investigation, reports on the
health status of office workers after exposure to aerosols containing S. chartarum.
Intensity and duration of exposure was related to illness. Statistically significant
differences for more exposed groups were increased lower respiratory symptoms,
dermatological, eye and constitutional symptoms, chronic fatigue, and allergy history.
Duration of employment was associated with upper respiratory, skin and central nervous
system disorders. A trend for frequent upper respiratory infections, fungal or yeast
infections, and urinary tract infections was also observed. Abnormal findings for
components of the immune system were quantified, and it was concluded that higher and
longer indoor exposure to S. chartarum results in immune modulation and even slight
immune suppression, a finding that supports the observation of more frequent infections.
Three articles describing different aspects of an investigation of acute pulmonary
hemorrhage in infants, including death of one infant, have been published recently, as
well as a CDC evaluation of the investigation (Montaña et al., 1997; Etzel et al., 1998;
Jarvis et al., 1998; MMWR, 2000; CDC, 1999). The infants in the Cleveland outbreak
were reported with pulmonary hemosiderosis, a sign of an uncommon of lung disease that
involves pulmonary hemorrhage.
Stachybotrys chartarum was shown to have an association with acute pulmonary
bleeding. Additional studies are needed to confirm association and establish causality.
Animal experiments in which rats and mice were exposed intranasally and intratracheally
to toxic strains of S. chartarum demonstrated acute pulmonary hemorrhage (Nikkulin et
al. 1996). A number of case studies have been more recently published. One involving an
infant with pulmonary hemorrhage in Kansas, reported significantly elevated spore
counts of Aspergillus/Penicillium in the patient’s bedroom and in the attic of the home.
Stachybotrys spores were also found in the air of the bedroom, and the source of the
spores tested highly toxigenic (Flappan et al., 1999). In another case study in Houston,
Stachybotrys was isolated from bronchopulmonary lavage fluid of a child with
pulmonary hemorrhage. (Elidemir et al., 1999), as well as recovered from his water
damaged-home. The patient recovered upon removal and stayed well after return to a
cleaned home. Another case study reported pulmonary hemorrhage in an infant during
47
induction of general anesthesia. The infant was found to have been exposed to S.
chartarum prior to the anesthetic procedure (Tripi et al., 2000). Still another case
describes pulmonary hemorrhage in an infant whose home contained toxigenic species of
Penicillium and Trichoderma (a mold producing trichothecene poisons similar to the ones
produced by S. chartarum) as well as tobacco smoke (Novotny and Dixit, 2000).
Toxicologically, S. chartarum can produce extremely potent trichothecene poisons, as
evidenced by one-time lethal doses in mice (LD50) as low as 1.0 to 7.0 mg/kg, depending
on the toxin and the exposure route. Depression of immune response, and hemorrhage in
target organs are characteristic for animals exposed experimentally and in field exposures
(Ueno, 1980; Jakab et al., 1994).
While there are insufficient studies to establish cause and effect relationships between
Stachybotrys exposure indoors and illness, including acute pulmonary bleeding in infants,
toxic endpoints and potency for this mold are well described. What is less clear, and has
been difficult to establish, is whether exposures indoors are of sufficient magnitude to
elicit illness resulting from toxic exposure.
Some of these difficulties derive from the nature of the organisms and the toxic products
they produce and varying susceptibilities among those exposed. Others relate to problems
common to retrospective case control studies. Some of the difficulties in making the
connection between toxic mold exposures and illness are discussed below.
Limitations in Sampling Methodology, Toxicology, and Epidemiology of Toxic Mold
Exposure
Some of the difficulties and limitations encountered in establishing links between toxic
mold contaminated buildings and illness are listed here:
1. Few toxicological experiments involving mycotoxins have been performed using
inhalation, the most probable route for indoor exposures. Defenses of the
respiratory system differ from those for ingestion (the route for most mycotoxin
experiments). Experimental evidence suggests the respiratory route to produce
more severe responses than the digestive route (Cresia et al., 1987)
2. Effects from low level or chronic, low level exposures, or ingestion exposures to
mixtures of mycotoxins, have generally not been studied, and are unknown.
Effects from high level, acute sub-acute and sub-chronic ingestion exposures to
single mycotoxins have been studied for many of the mycotoxins isolated. Other
mycotoxins have only information on cytotoxicity or in vitro effects.
3. Effects of multiple exposures to mixtures of mycotoxins in air, plus other toxic air
pollutants present in all air breathed indoors, are not known.
4. Effects of other biologically active molecules, having allergic or irritant effects,
concomitantly acting with mycotoxins, are not known.
48
5. Measurement of mold spores and fragments varies, depending on instrumentation
and methodology used. Comparison of results from different investigators is
rarely, if ever, possible with current state of the art.
6. While many mycotoxins can be measured in environmental samples, it is not yet
possible to measure mycotoxins in human or animal tissues. For this reason
exposure measurements rely on circumstantial evidence such as presence of
contamination in the patient’s environment, detection of spores in air, combined
with symptomology in keeping with known experimental lesions caused by
mycotoxins, to establish an association with illness.
7. Response of individuals exposed indoors to complex aerosols varies depending on
their age, gender, state of health, and genetic make-up, as well as degree of
exposure.
8. Microbial contamination in buildings can vary greatly, depending on location of
growing organisms, and exposure pathways. Presence in a building alone does not
constitute exposure.
9. Investigations of patients’ environments generally occur after patients have
become ill, and do not necessarily reflect the exposure conditions that occurred
during development of the illness. All cases of inhalation exposure to toxic agents
suffer from this deficit. However exposures to chemicals not generated
biologically can sometimes be re-created, unlike those with active microbial
growth. Indoor environments are dynamic ecosystems that change over time as
moisture, temperature, food sources and the presence of other growing
microorganisms change. Toxin production particularly changes with age of
cultures, stage of sporulation, availability of nutrients, moisture, and the presence
of competing organisms. After-the-fact measurements of environmental
conditions will always reflect only an estimate of exposure conditions at the time
of onset of illness. However, the presence of toxigenic organisms and their toxic
products, are indicators of presumed exposure, which together with knowledge of
lesions and effects produced by toxins found, can establish association.
49
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Websites
American Academy of Allergy, Asthma & Immunology (AAAAI) http://www.aaaai.org
American College of Occupational and Environmental Medicine (ACOEM)
http://www.siouxlan.com/acoem/
American Conference of Governmental Industrial Hygienists, Inc. (ACGIH)
http://www.acgih.org
American Industrial Hygiene Association (AIHA) http://www.aiha.org
American Lung Association (ALA) http://www.lungusa.org
American Society of Heating, Refrigeration, and Air-Conditioning Engineers, Inc.
(ASHRAE) http://www.ashrae.org
Association of Occupational and Environmental Clinics (AOEC) http://www.aoec.org
Association of Specialists in Cleaning and Restoration (ASCR) http://www.ascr.org
Asthma and Allergy Foundation of America (AAFA) http://www.aafa.org
Asthma and Allergy Network/Mothers of Asthmatics, Inc. (AAN*MA)
http://www.aanma.org
Canada Mortgage and Housing Corporation (CMHC) http://www.cmhcschl.gc.ca/cmhc.html
64
Carpet and Rug Institute (CRI) http://www.carpet-rug.com
Centers for Disease Control and Prevention (CDC) http://www.cdc.gov
CDC’s National Center for Environmental Health (NCEH)
http://www.cdc.gov/nceh/airpollution/mold/stachy.htm
Energy and Environmental Building Association http://www.eeba.org
Federal Emergency Management Agency (FEMA) http://www.fema.gov/mit
Health Canada, Health Protection Branch, Laboratory Centre for Disease Control, Office
of Biosafety http://www.hc-sc.gc.ca/main/lcdc/web/biosafty/msds/index.html
Institute of Inspection, Cleaning and Restoration Certification (IICRC)
http://www.iicrc.org
International Sanitary Supply Association (ISSA) http://www.issa.com
International Society of Cleaning Technicians (ISCT) http://www.isct.com
Material Safety Data Sheets (MSDSs) – Cornell University
http://msds.pdc.cornell.edu/msdssrch.asp
MidAtlantic Environmental Hygiene Resource Center (MEHRC) http://www.mehrc.org
National Air Duct Cleaners Association (NADCA) http://www.nadca.com
National Antimicrobial Information Network (NAIN) http://nain.orst.edu
National Association of Home Builders (NAHB) ToolBase Services
http://www.toolbase.org/secondaryT.asp?TrackID=&CategoryID=1554
National Association of the Remodeling Industry (NARI) http://www.nari.org
National Institute of Allergy and Infectious Diseases (NIAID) http://www.niaid.nih.gov
National Institute of Building Sciences (NIBS) http://www.nibs.org
National Institute for Occupational Safety and Health (NIOSH) http://www.cdc.gov/niosh
National Jewish Medical and Research Center http://www.njc.org
National Pesticide Telecommunications Network (NPTN) http://ace.orst.edu/info/nptn
New York Department of Health, Bureau of Environmental and Occupational Disease
Epidemiology http://www.ci.nyc.ny.us/html/doh/html/epi/moldrp1.html
65
Occupational Safety & Health Administration (OSHA) http://www.osha.gov
Sheet Metal & Air Conditioning Contractors’ National Association (SMACNA)
http://www.smacna.org
Smithsonian Center for Materials Research and Education (SCMRE)
http://www.si.edu/scmre
University of Michigan Herbarium http://www.herb.lsa.umich.edu
University of Tulsa Indoor Air Program http://www.utulsa.edu/iaqprogram
Water Loss Institute, Association Specialists in Cleaning and Research
http://www.ascr.org/wli/
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