State of the Science on Molds and Human Health
Statement of
Stephen C. Redd, M.D.
Centers for Disease Control and Prevention
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 mold exposures in poorly maintained housing and other indoor environments and their effect om people’s health. While there remain many unresolved scientific questions, we do know that exposure to high levels of molds causes some illnesses in susceptible people. Because molds can be harmful, it is important to maintain buildings, prevent water damage and mold growth, and clean up moldy material.
Today I will briefly summarize for the committee
- CDC’s perspective on the state of the science relating to mold and heatlh effects in people;
- CDC’s efforts to evaluate health problems associated with molds,
- CDC’s collaborations with other Federal agencies related to mold and people’s health;
- CDC’s collaboration with the Institute of Medicine on mold and health; and
- CDC’s next steps regarding mold and health.
The State of the Science
Fungi are a kingdom of organisms that include muscrooms, mildews, molds 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. Molds are ubiquitous in nature and grow almost anywhere indoors and outdoors. More than 1,000 different kinds of indoor molds have been found in US homes. Molds 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,. Molds need moisture and food to grow and their growth is stimulated by warm , damp, and humid conditions.
Molds can cause illnesses in situations other than humid indoor environments. We have documented that molds cn cause infections is susceptible people, particularly in hospital settings where 9% of hopital-acquired (mosoomial) infections are caused by fungi. Respiratory infections due to inhalation of the fungus Aspergillus have been documented mostly in immunocompromised indivduals. Molds also have been associated with some cancers. Two mold-produced toxins (aflatoxins and ochratoxin A) have been classified by the National Toxicology Program as human carcinogens. 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 mold exposures. In industrial and agricultural settings, various forms or hypersensitivity pneumonitis (e.g. farmer’s lung, woodworker’s lung, malt worker’s lung), and other allergic responses and infectious repiratory diseases (e.g., aspergillosis) have been reported. Farmer’s lung is caused byThermoactinomycetes 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 mold-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 recurren acute and chronic hypersensitity pneumonitis in office workers. American Journal of Epidemiology 125:631-638)).
We also know that molds can cause illness when people are exposed to extensive mold growth indoors, It its 1993 report “Indoor Allergens,” the Institute of Medicine (IOM) concluded that airborne fungal allergens wer most often associated with allergic deseases, such as allergic rhinitis/conjuntivitis, 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 mold and exacerbations of asthma. The IOM also stated there there was inadequate evidence that molds caused people to become asthmatic.
For more information or to receive this document in its entirety, please contact Vik Ahuja, CIAQP at Vahuja@PureAirControls.com or (800) 422-7873, ext. 804.
