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Statement for the Record Before the Subcommittees on
Oversight and Investigations and Housing and Community Opportunity
Committee on Financial Services, United States House
of Representatives
State of the Science on Moulds and Human Health
Statement of
Stephen C. Redd, M.D.
Chief, Air Pollution and Respiratory Health Branch,
National Center for Environmental Health Centers for Disease Control and
Prevention, U.S. Department of Health and Human Services
Thursday, July 18, 2002, U.S.
House
Financial Services Subcommittee
Good afternoon. I am Dr. Stephen Redd, the lead CDC scientist on air
pollution and respiratory health at the Centers for Disease Control and
Prevention (CDC). Accompanying me today is Dr. Thomas Sinks, Associate
Director for Science of environmental issues at CDC. We are pleased to
appear before you today on behalf of the CDC, an agency whose mission is
to protect the health and safety of the American people. I want to thank
you for taking the time to hear about the mould exposures in poorly
maintained housing and other indoor environments and their effect on
people’s health. While there remain many unresolved scientific
questions, we do know that exposure to high levels of moulds causes some
illnesses in susceptible people. Because moulds can be harmful, it is
important to maintain buildings, prevent water damage and mould
growth, and
clean up moldy materials. Today I will briefly summarize for the
committee
· CDC’s perspective on the state
of the science relating to mould and health effects in people;
· CDC’s efforts to evaluate
health problems associated with moulds,
· CDC’s collaborations with other
Federal agencies related to mould and people’s health;
· CDC’s collaboration with the
Institute of Medicine on mould and health; and
· CDC’s next steps regarding mould
and health.
Fungi are a kingdom of organisms that include mushrooms, mildews, moulds,
and yeasts. It is estimated
that there are between 50,000 and 250,000 species of fungi, and fewer than
200 have been
described as human pathogens that can cause infections. moulds are
ubiquitous in nature and grow almost anywhere indoors and outdoors. More
than 1,000 different kinds of indoor moulds have been found in U.S. homes.
moulds spread and reproduce by making spores, which are very small and
lightweight, able to travel through air, capable of resisting dry, adverse
environmental conditions, and hence capable of surviving a long time.
moulds need moisture and food to grow, and their growth is stimulated by
warm, damp, and humid conditions.
moulds can cause illnesses in situations other than humid indoor
environments. We have documented that moulds can cause infections in
susceptible people, particularly in hospital settings where 9% of
hospital-acquired (nosocomial) infections are caused by fungi. Respiratory
infections due to inhalation of the fungus Aspergillus
have been documented mostly in immunocompromised individuals. moulds
also have been associated with some cancers. Two mould-produced toxins (aflatoxins
and ochratoxin A) have been classified by the National Toxicology Program
as human carcinogens (http://ntp-server.niehs.nih.gov/). Chronic ingestion
of these toxins from eating contaminated foods has been associated with
liver and kidney tumors in animals and people.
We also know that respiratory illnesses among workers may be attributed to
mould exposures. In industrial and agricultural settings, various forms of
hypersensitivity pneumonitis (e.g., farmer’s lung, woodworker’s lung,
malt worker’s lung), and other allergic responses and infectious
respiratory diseases (e.g., aspergillosis) have been reported. Farmer’s
lung is caused by Thermoactinomycetes
species or fungi found in moldy hay,
straw, or grain dust. Farmer’s lung has been extensively reported in
many countries including the United States, Canada, The Scandinavian
countries, France, and other European countries. Reported prevalence of
farmer’s lung ranges from 0.5% to 9.6% in farming populations.
Outbreaks of hypersensitivity pneumonitis also have been reported in
office buildings in relation to exposures to mould-contaminated humidifiers
and ventilation systems (Arnow et al. 1987. Early
detection of hypersensitivity pneumonitis in office workers, American
Journal of Medicine 64:236-242 and
Hodgson et al. 1987. An outbreak of
recurrent acute and chronic hypersensitivity pneumonitis in office
workers. American Journal of Epidemiology
125:631-638)).
We also know that moulds can cause illness when people are exposed to
extensive mould growth indoors. In its 1993 report "Indoor
Allergens," the Institute of Medicine (IOM) concluded that airborne
fungal allergens were most often associated with allergic diseases, such
as allergic rhinitis/conjunctivitis, allergic asthma, and hypersensitivity
pneumonitis. In its 2000 report "Clearing the Air: Asthma and Indoor
Air Exposures," IOM concluded that there is sufficient evidence of an
association between exposure to mould and exacerbations of asthma. The IOM
also stated that there was inadequate evidence that moulds caused people to
become asthmatic.
We do not know whether moulds cause other adverse health effects, such as
pulmonary hemorrhage, memory loss, or lethargy. We also do not know if the
occurrence of mould-related illnesses
is increasing. Other than surveillance for hospital-acquired infections,
there is no system to
track the public’s exposure to and the possible health effects of mould.
Exposure to mould does not always result in a health problem. However,
routine measures should be taken to prevent mould growth indoors because
some people are, or may become, allergic to it. For people who are
allergic to mould, common effects include hay-fever-like allergic
symptoms. Certain individuals with chronic respiratory disease (chronic
obstructive pulmonary disease or asthma) may experience difficulty
breathing when exposed to mould. Also, people with immune suppression or
underlying lung disease are more susceptible to fungal infections.
CDC efforts to evaluate the health
problems associated with moulds
CDC has conducted several activities related to mould in wet indoor
environments and its effect on people’s health.
·In 1994, CDC conducted two epidemiologic investigations of reported
clusters of the acute onset of bleeding from the lungs of very young
children (pulmonary hemorrhage or idiopathic pulmonary hemosiderosis). In
one investigation a possible association was reported between exposure to
the mould Stachybotrys
atra (S.
atra) and disease. This association was not reported in the second
investigation. In a further review of our first investigation, CDC
reviewers and an external panel of experts determined that there was
insufficient evidence of any association between exposure to S. atra or
other toxic fungi and idiopathic pulmonary hemosiderosis in infants. CDC
has plans to further evaluate the relationship between pulmonary
hemorrhage and S.
atra through state-based surveillance,
further investigations of identified disease clusters, and focused
research studies.
·In July 2001, following flooding in North Dakota, CDC investigated
Turtle Mountain Reservation residents’ concerns that mould contaminating
their homes might be contributing to an increase in illness among tribal
members. CDC assessed both the physical and environmental condition of the
homes to identify any environmental hazards, including the presence of
mould, and collected information on health conditions of the individuals
living in the homes. An interim report identified several existing hazards
unrelated to mould and made recommendations to address these hazards. The
final report is expected in October 2002. In addition to working with the
Indian Health Service and the Federal Emergency Management Agency (FEMA)
on this project,
·CDC also worked with the U.S. Department of Housing and Urban
Development (HUD) to identify procedures that might be implemented to
assess conditions of HUD homes that would help to prevent mould.
· CDC responded to a request from the State of Texas and the City of
Houston in the summer of 2001, after the city experienced significant
flooding, to assess the conditions of the buildings and provide advice on
cleanup and repair of affected buildings. The emphasis of this technical
assistance was cleanup and prevention of further mould growth and
prevention of unnecessary exposure.
· In 1999, CDC’s occupational health experts began a 5-year initiative
on work-related asthma in offices
and schools, with an emphasis on moisture and mould exposures. We have a
targeted research
program regarding work-related asthma that includes evaluations of
workplaces, intervention studies, and recommendations for reducing the
risk of respiratory disease, and provision of information to management,
employees and environmental health and safety professionals. The research
aims are to be achieved utilizing problem buildings identified through the
CDC’s occupational Health Hazard Evaluation program. Specific objectives
include methods development and testing, specifically with regard to
state-of-the-art techniques for assessing indoor air quality-related
exposures; quantification of objective medical indices related to asthma
and other lung diseases; and planned case-control, cross-sectional, and
intervention studies directed towards risk factor identification and
assessment.
So far, the results include the following:
· there were significant relationships between reports of work-related
respiratory disease and visual assessment of water and mould-damage in two
studies;
· there were significant relationships between endotoxin and ultra-fine
particles in air and work-related respiratory symptoms; and
· there were significant relationships between indicators of mould in
chair and floor dust and work-related respiratory symptoms.
· CDC is planning an occupational and environmental research project
regarding bioaerosols in
schools to address children’s and
teacher’s health issues.
· CDC is working to address indoor air quality issues, including mould, in
partnership with stakeholders through the National Occupational Research
Agenda (NORA). NORA efforts have resulted in development of the research
priorities paper, "Improving the Health of Workers in Indoor
Environments: Priority Research Needs for a National Occupational Research
Agenda," which
identifies important areas for future research. The paper has been
accepted for publicationin the American Journal of Public Health (AJPH).
CDC’s collaborations with other
Federal agencies
CDC is working with federal, state, local, and tribal governments to
investigate and respond to mould-related problems. I have already mentioned
that we work with HUD, FEMA, and the Indian Health Service on mould issues.
We have also assisted the U.S. Environmental Protection Agency (EPA)
Indoor Environments Division in the development of a guide for mould
remediation in schools and large buildings and in the development of a
brief guide to mould for homeowners. CDC is participating in the
development of a World Health Organization guidance document on exposures
to biological agents in the indoor environment; this document should be
finalized in the year 2003. CDC also has worked with the Council of State
and Territorial Epidemiologists in the development of case definitions and
classifications for pulmonary hemorrhage in infants.
CDC’s collaboration with the
Institute of Medicine
CDC is funding the IOM to evaluate the relationship between damp or moldy
indoor environments and the manifestation of adverse health effects. Under
this project, the IOM will conduct
a comprehensive review of the scientific literature. The review will focus
on respiratory and
allergic symptoms and other non-allergic health effects. The IOM will
include recommendations or suggest guidelines for public health
interventions and future research. The IOM began the study in January 2002
and is expected to complete it in the late summer or early fall of 2003.
To date, the IOM committee conducting the study has held two meetings, the
first on March 26, 2002 and the second on June 17, 2002. A third meeting
is planned for Fall 2002. The report will be disseminated to audiences
such as relevant federal agencies, state public health and indoor air
quality officials, academic institutions and researchers, environmental
firms, and the building industry.
CDC’s Next Steps
In response to concerns about mould and the gaps in scientific knowledge,
CDC is currently developing an agenda for research, service, and education
related to moulds. The results of this effort will ultimately enable CDC to
(1) make recommendations for reducing mould contamination, (2) identify
environmental conditions that contribute to the occurrence of disease
following mould exposure, and (3) assist state and local health departments
in improving their capacity to investigate mould exposures. CDC is working
to help strengthen state and local capacity to respond to requests
regarding moulds. Because there are no quantitative standards, guidelines
or uniform recommendations for responding to mould in indoor environments,
each state or local health department responds to public inquiries based
solely on its own experience. CDC is working with the Council of State and
Territorial Epidemiologists to:
· develop an inventory of state Indoor Air Quality programs;
· determine the extent to which these programs are
coordinated to respond to issues related to indoor mould exposures;
· identify resources that states need in order to develop and implement
appropriate responses; and
· develop a coordinated public health response strategy to mould exposure.
CDC will continue to investigate and evaluate the health effects of and
quantify the risks associated with, exposure to mould and poor indoor air.
The expectation is that such studies will help to identify the
environmental factors and antecedents associated with mould contamination
and factors that determine poor health outcomes. For example, CDC is
developing a protocol for investigating the possible health effects of
exposure to mould in indoor school environments. CDC will use the
knowledge, experience and skill gained from these investigations and
evaluations to translate science-based findings into appropriate public
health interventions to reduce any health risk found to be associated with
mould exposure.
There are a number of barriers that need to be overcome in investigating
the possible effects of moulds on health. There are no accepted standards
for mould sampling in indoor environments or for analyzing and interpreting
the data in terms of human health. moulds are ubiquitous in the
environment, and can be found almost anywhere samples are taken. It is not
known, however, what quantity of mould is acceptable in indoor environments
with respect to health. Because of difficulties related to sampling for
mould, most studies have tended to be based primarily on baseline
environmental data rather than human dose-response data. For these
reasons, and because individuals have different sensitivities to moulds,
setting standards and guidelines for indoor mould exposure
levels is difficult and may not be practical. Despite the lack of
standards,
CDC concurs with EPA’s recommendation to remedy mould contamination in
indoor environments to prevent negative health effects.
Summary
We do know that people who are exposed to moulds may experience a variety
of illnesses. Fungi account for 9% of nosocomial infections, that is,
infections originating or taking place in a hospital. Ingestion of foods
contaminated with certain toxins produced by moulds is associated with
development of human cancer. Many respiratory illnesses among workers may
be attributed to mould exposures. Uncommon illnesses that collectively can
be called hypersensitivity pneumonitis are caused by chronic exposures to
high concentrations of mould and are almost exclusively limited to certain
agricultural workers in particularly moldy environments. Common illnesses
caused by moulds include allergic conditions such as hay fever and asthma.
Because moulds can be harmful, CDC concurs with the general recommendations
of agencies such as EPA and FEMA, which offer information on preventing
and cleaning up mould growth in indoor environments. Linkages between
indoor airborne exposures to moulds and other health effects, such as
bleeding from the lung, or memory loss, have not yet been scientifically
substantiated. CDC and other organizations are taking steps to fill the
gaps in our knowledge about linkages between exposure to mould and human
health.
Thank you again for the opportunity to testify. I would be happy to answer
any questions that you have.
State of the Science on moulds and
Human Health July 18, 2002
U.S. House Financial Services
Subcommittees
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