Inhalational Health Effects of Mold

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A Spreading Concern: Inhalational Health Effects of Mold

by Environmental Health Perspectives*

http://www.ehponline.org/members/2007/115-6/EHP115pa300PDF.PDF

The issue of mold contamination has drawn the national and

international spotlight on the heels of publicity about prominent

situations, such as a hotly contended link between mold and severe

illness—and one death—in 10 Ohio infants in 1993 and 1994; a major

2001 insurance battle over the moldy Dripping Springs, Texas, house

of Melinda Ballard and her family; the mushrooming mold infestations

indoors and out along the Gulf Coast after Hurricanes Katrina and

Rita slammed ashore in 2005; and the mold infestation that helped

spur the February 2007 outcry over the treatment given to

recuperating soldiers at Walter Army Medical Center. As

recently as 25 years ago, inhaled mold was considered primarily a

nuisance, not a serious health threat. But the growing scientific

and medical evidence suggests the threat is widespread and, for some

people, quite serious.

In the 9 June 2006 report Mold Prevention Strategies and Possible

Health Effects in the Aftermath of Hurricanes and Major Floods, the

CDC concluded that " excessive exposure to mold-contaminated

materials can cause adverse health effects in susceptible persons

regardless of the type of mold or the extent of contamination. " The

CDC based some of its findings on a landmark 2004 report, Damp

Indoor Spaces and Health, by the Institute of Medicine (IOM) of the

National Academies. Relying on the IOM report, and dozens of studies

and reports that have been published since, many organizations and

individuals that must deal regularly with mold problems have begun

to take steps to reduce the threat.

But many of the puzzle pieces—exactly who is vulnerable, to what

extent, and under what conditions—are still missing. The vast

information gaps that remain continue to feed significant

controversy in the legal, insurance, political, scientific, medical,

public health, and building design, construction, management, and

maintenance arenas.

Growing Suspicion

Of the 100,000 or so known fungal species found on the planet, about

500 species are currently thought to be harmful to people, according

to the CDC. Some of those that pose ingestion threats (such as

Aspergillus, via contaminated grains and nuts) or skin infection

threats (such as Trichophyton, which causes athlete's foot) have

been either well-recognized or strongly suspected for years, even

centuries. As for inhalational threats, although molds such as

Stachybotrys and Aspergillus have received perhaps the most popular

attention, scientists are not yet sure which species may be the

worst for human health.

A few threats from inhaled molds have been perceived for a long

time. Since the 1890s, outdoor settings in the U.S. Southwest have

been linked with coccidioidomycosis, caused by a fungus in the soil.

At least 50 years ago, there were some indications of mold-related

health problems in agricultural and certain occupational settings,

causing illnesses such as pneumomycotoxicosis. In areas near rivers

in the central United States, a fungus has been known for at least

30 years to cause blastomycosis. By about 25 years ago, there was

some initial evidence that damp indoor spaces were linked with

health problems such as bronchitis, asthma, cough, wheeze, and

shortness of breath. But there has been little specific knowledge

until recently.

Wherever they grow, molds must have some source of water and food.

The accumulating evidence has shown that problems with mold can

surface anywhere in the world after just one or two days of moisture

exposure, in settings wet or dry, hot or cold, north or south. The

same conditions that give rise to mold growth also support many

bacteria. Many components and emissions from these fungi and

bacteria are known or suspected to harm human health. Mycotoxins,

which are secondary fungal metabolites, have been one primary focus,

and more than 180 have already been identified. Other components of

fungi or bacteria in damp spaces that are known or suspected to pose

a threat include volatile organic compounds, live or dead spores,

fragments such as beta glucans, and numerous allergens.

Mycotoxins have often been the main point of contention in recent

insurance claims and lawsuits over suspected harm from moldy

buildings. In the 2004 EPA-funded report Guidance for Clinicians on

the Recognition and Management of Health Effects Related to Mold

Exposure and Moisture Indoors, researchers at the Center for Indoor

Environments and Health at the University of Connecticut Health

Center wrote that mycotoxins can elicit responses in almost anyone

they come in contact with, that the health effects are worrisome,

and that infants, at least, should be removed from suspect settings.

After reviewing the evidence available by 2004, the IOM concluded

there are moderately strong or at least limited links between damp

indoor spaces and a handful of health problems, such as asthma,

cough, wheeze, hypersensitivity pneumonitis, and a range of other

upper and lower respiratory problems. For other health problems

under suspicion based on many anecdotal accounts and limited

scientific and medical evidence, such as headache, memory loss,

nausea, diarrhea, diabetes, fatigue, and fever, the lack of

incontrovertible evidence was typically due to a lack of rigorous

research, not because of studies that conclusively disproved a

connection.

Among the weaknesses the IOM notes in many current studies is a

tendency to use self-reported visual or odor presence of mold,

instead of actual measurments of some kind, and little consideration

of multiple exposures, including additive or synergistic effects. In

addition, the committee noted that its findings did not address

people with compromised immune systems.

Why Now?

It is likely that building dampness and mold have caused widespread

but largely unrecognized adverse respiratory health effects for

centuries, says Fisk, acting division director for the

Environmental Energy Technology Division at the Lawrence Berkeley

National Laboratory. But the increasing immune-compromised

population around the world may be one reason why health problems

from inhaled mold and bacteria appear to be on the rise recently.

Population growth, higher percentage of elderly, emerging diseases

such as HIV, and increases in smoking and in many chronic illnesses

(often for unknown reasons) are only a few of the reasons that,

compared to just a century ago, there are hundreds of millions more

peoplewith weak or stressed immune systems. The CDC has identified

many immunocompromised subpopulations, as well as pregnant women, as

being potentially more vulnerable to exposures in damp indoor

spaces.

In addition, the dramatic increase in the percentage of people

living in urban areas may be playing a part. Researchers at Hospital

General Universitario Gregorio Maranon in Spain reported in the June

2006 issue of Medical Mycology that Aspergillus spores in outdoor

air are more common in urban than rural settings in the province of

Madrid. Worldwide population increases have also pushed more people

into wetter settings, such as coastal and riparian floodplains,

other bottomlands, and hurricane-prone areas.

Other risk factors arise from modern building practices,

conveniences, and shortcuts. Poorly built flat roofs cannot shed

rainwater, while venting clothes dryers indoors can direct moist air

to vulnerable interior surfaces. Tighter building envelopes in

modern homes slow the escape of water vapor associated with bathing,

cooking, and even breathing; newer homes also have insulation-filled

cavities that dry slowly after the inevitable small leaks. Further,

the tight seal on newer housing may exacerbate problems during the

heating of buildings, when humid indoor air contacts cold walls or

windows (although the reverse is true for an air-conditioned

building when it is hot outdoors). Also, there are many anecdotal

reports that molds grow more readily on the paper-coated surfaces of

modern wallboard than on older plaster walls. A few companies have

introduced wallboard products they say are more resistant to mold

growth, but some critics say these products still may support mold

in settings that routinely get wet, such as kitchens, bathrooms, or

areas with leaks of some type.

The substantial increase in air conditioning all over the world is

another potential culprit, with more than fifteen studies

consistently indicating a strong link with numerous respiratory

symptoms, says Fisk. Microbes thriving in air conditioning systems,

including fungi and bacteria, likely contribute to that link, he

says.

Buildings have often been constructed without sufficient attention

paid to indoor water problems. In an assessment of health and

economic impacts of dampness and mold published in the June 2007

issue of Indoor Air, Fisk and EPA indoor environment specialist

Mudarri found that approximately 47% of U.S. homes have

dampness or mold problems. Their review of other studies led them to

conclude that schools, offices, and institutional buildings have

similar problems. The EPA Building Assessment Survey and Evaluation

Study of 100 randomly selected U.S. office buildings supports that

conclusion, with its finding, reported at the 2002 9th International

Conference on Indoor Air Quality and Climate, that 45% had ongoing

water damage problems. University of Cincinnati environmental health

professor Tiina Reponen and her colleagues noted in a May 2006 study

in the Journal of Occupational and Environmental Hygiene that the

percentage of buildings of all types that have mold contamination is

likely much higher in tropical and subtropical settings.

Cracking the Mold Code

Many new studies have provided additional evidence that mold likely

deserves serious attention. Fisk and Mudarri demonstrated in their

June 2007 assessment that 21% of current U.S. asthma cases may be

attributable to dampness and mold in homes, with schools, offices,

and institutional buildings playing a similar unhealthy role. In a

companion meta-analysis of 33 studies also published in the June

2007 issue of Indoor Air, Fisk and Berkeley Laboratory colleagues

found that dampness and mold exposures increase the occurrence of a

range of respiratory problems by 30–50%.

Many other examples of potentially significant findings have been

published in the past three years. In the May 2004 issue of EHP,

Kati Huttunen ofthe Finnish National Public Health Institute and

colleagues demonstrated synergism between various indoor fungi and

the bacterium Streptomyces californicus, includingincreases in

production of tumor necrosis factor–á and interleukin-6 in various

circumstances. In the February 2006 issue of Toxicology and Applied

Pharmacology, a Michigan State University team described exacerbated

damage when exposure to a mycotoxin was preceded by exposure to a

bacterial fragment, in this case the endotoxin component

lipopolysaccharide. More detailed knowledge of the wide-ranging

olfactory system damage that a mycotoxin can wreak appeared in the

July 2006 issue of EHP, and in the following month's issue, Case

Western Reserve University researchers described how they identified

potential biomarkers of mycotoxin exposure. An article in the 3 June

2007 issue of Toxicology addresses elucidation by a second Finnish

team of specific accelerated genotoxic and cytotoxic damage by a

cultivated fungus–bacterium mixture.

EPA research biologist Vesper and colleagues have performed

a series of experiments to develop better methodology for predicting

mold exposure risk. After almost a decade and a half of work, they

have created a Relative Moldiness Index that uses quantitative

polymerase chain reaction to measure concentrations of 36 indicator

mold species present in floor dust samples taken inside a building.

This standardized analysis, described in the January 2007 issue of

the Journal of Exposure Science and Environmental Epidemiology, is

used to indicate the amount of water damage in a home, providing

more accurate exposure information that may help to predict health

problems. They expect to soon publish information about its

successor, the Environmental Relative Moldiness Index, which covers

more buildings in more geographic settings, and benefits from

improved sampling protocols and analysis of information.

As researchers explore the potential contributions of damp

conditions to human health problems, they'll need to be careful

about exactly which test animals they use. Several reports, such as

a Harvard study in the October 2006 American Journal of Respiratory

Cell and Molecular Biology, have shown that different mouse strains

vary significantly in their biological responses to a tested fungus.

In addition, scientists face the usual uncertainties inherent in

extrapolating results from any animal testing to humans.

Not Messing Around

Until very recently, building design was not widely acknowledged as

an important factor in preventing water problems. As recently as

2005, the American Institute of Architects (AIA) emphasized in an

issue brief to its members that mold problems are tied to

maintenance of a building's plumbing and ventilation systems, not

the initial building design. Just a year later, however, an article

in the 29 September 2006 edition of the AIA publication AIArchitect

emphasized that design details are critical in preventing mold

problems. Some of the points of vulnerability highlighted included

roof underlayments, concrete foundation sealants, flashing around

windows and doors, and grading around the building.

Many contractors also are paying more attention. " We've told

builders to be vigilant about moisture issues in all stages and to

treat it seriously, " says Jaffe, vice president of

construction liability and legal research with the National

Association of Home Builders. But problems still occur, he

acknowledges, citing the continuing stream of insurance claims and

lawsuits over mold concerns in both residential and nonresidential

buildings: " It's an ongoing issue. We're always looking for ways to

improve. " Other organizations, such as the American College of

Occupational and Environmental Medicine and the American College of

Medical Toxicology, remain skeptical that mold poses a serious

threat to more than a small number of people.

Doubts about mold threats, uncertainty over who should be

responsible for problems that may arise, and variable guidance on

appropriate remediation continue to play a role in political

responses to mold concerns. At least 46 states and the District of

Columbia have approved some type of insurance coverage limitation

for residential policies, and such exclusions are becoming more

common for commercial properties, says Barry, director of

media relations for the U.S. Insurance Information Institute.

According to the National Conference of State Legislatures, since

2001 at least 31 states have approved, have rejected, or continue to

consider laws that address mold problems in some way, such as

contractor liability, real estate agent or landlord liability for

disclosure, or licensing of mold inspectors, testers, and

remediators.

Given the evidence at hand, Health Canada has determined that mold

may pose a health hazard, and on 31 March 2007 released brief

recommendations for cleaning up mold in residences.The EPA is

developing guidelines for moisture control " best practices " in all

phases of design, construction, and maintenance, and may finalize

the guidelines in 2008, says Kolb, an environmental health

scientist with the agency's Indoor Environments Division.

Much more information continues to surface through research and

public health efforts around the world, and there is some

communication among various groups. But " not much has been done to

move the science forward that's applicable to broad populations, "

says Stock, a toxicologist with the CDC's National Center

for Environmental Health. One roadblock may be that there is no

concerted, coordinated national or international effort to address

the dozens of information gaps identified in the IOM report.

Given such shortcomings, " We're still quite some way from being able

to set [exposure and remediation] standards, " says Marsha Ward, a

principal investigator in the EPA Immunotoxicology Branch. In the

interim, groups such as the Restoration Industry Association are

giving it their best shot and updating remediation guidelines for

their members, targeting completion by 2008, says communications

director Harman.

Another critical area requiring attention is the very limited

repertoire of effective medical treatments to prevent illness or

treat people experiencing certain ill effects such as allergic

bronchopulmonary aspergillosis and acute idiopathic pulmonary

hemorrhage, says Lynnette Mazur, a professor of pediatrics at the

University of Texas Medical School at Houston and coauthor of a 6

December 2006 Pediatrics policy statement on noninfectious health

effects from molds. Mazur points out that with respect to allergic

rhinitis and asthma, however, there are very effective environmental

and pharmacological treatments available.

Regardless of all the remaining uncertainties, the overall

recommendations of many organizations and agencies worldwide are

reaching a common conclusion: Don't mess with mold. If you can see

or smell it—and especially if health problems are occurring—clean it

out, throw it out, or get out.