History
In the 1930s, mold was identified as the cause behind the mysterious deaths of farm animals in Russia and other countries. Stachybotrys chartarum was found growing on wet grain used for animal feed. The illnesses and deaths also occurred in humans when starving peasants ate large quantities of rotten food grains and cereals that were heavily overgrown with the Stachybotrys mold.
In the 1970s, building construction techniques changed in response to the changing economic realities including the energy crisis. As a result, homes and buildings became more airtight. Also, cheaper materials such as drywall came into common use. The newer building materials reduced the drying potential of the structures making moisture problems more prevalent. This combination of increased moisture and suitable substrates contributed to increased mold growth inside buildings.
Today, the US Food and Drug Administration and the agriculture industry closely monitor mold and mycotoxin levels in grains and foodstuffs in order to keep the contamination of animal feed and human food supplies below specific levels. In 2005 Diamond Pet Foods, a US pet food manufacturer, experienced a significant rise in the number of corn shipments containing elevated levels of aflatoxin. This mold toxin eventually made it into the pet food supply, and dozens of dogs and cats died before the company was forced to recall affected products.
Health issues and symptoms
See also: Category:Fungal diseases
Some specific molds and/or their mycotoxins can exacerbate or cause illnesses, including allergenic or irritant effects, or infection.
Exposure to fungi in indoor air in some occupational settings may present a significant threat to health, but this has not been demonstrated with any confidence in residential environments.
Molds can be allergenic, causing irritations of eye, nose, throat, and lungs. In response to this, environmental health research has yielded tests such as the MELISA test, which can determine whether a person is allergic to a specific mold.
Molds may excrete liquids or low-volatility gases, but the concentrations are so low that frequently they cannot be detected even with sensitive analytical sampling techniques. Sometimes these by-products are detectable by odor, in which case they are referred to as "ergonomic odors" meaning the odors are detectable, but do not indicate toxicologically significant exposures.
It is thought[citation needed] that all molds may produce mycotoxins and thus all molds may be potentially toxic if large enough quantities are ingested, or the human becomes exposed to extreme quantities of mold. Mycotoxins are not produced all the time, but only under specific growing conditions. Mycotoxins are harmful or lethal to humans and animals only when exposure is high enough. Some of the most deadly chemicals on the planet are similarly harmless at the concentrations normally encountered in ambient air.
Mycotoxins can be found on the mold spore and mold fragments, and therefore they can also be found on the substrate upon which the mold grows. Routes of entry for these insults can include ingestion, dermal exposure and inhalation.
Dermatophytes are the parasitic fungi that cause skin infections such as athlete's foot and tinea cruris. Most dermataphyte fungi take the form of a mold, as opposed to a yeast, with appearance (when cultured) that is similar to other molds.
Opportunistic infection by molds such as Penicillium marneffei and Aspergillus fumigatus is a common cause of illness and death among immunocompromised people, including people with AIDS.
Environmental illnesses can be difficult for healthcare practitioners to diagnose. People living in houses contaminated with mold are often aware of the fact due to the appearance of molds.[citation needed]
Mold spores
See also: spores, allergy, allergens, bioaerosol, and allergic bronchopulmonary aspergillosis
Health problems associated with high levels of airborne mold spores include allergic reactions, asthma episodes, irritations of the eye, nose and throat, infections, sinus congestion, and other respiratory problems. When inhaled by an immunocompromised individual, some mold spores may begin to grow on living tissue, attaching to cells along the respiratory tract and causing further problems. Generally, when this occurs, the illness is an epiphenomenon and not the primary pathology.
A serious health threat from mold exposure for immunocompromised individuals is systemic fungal infection. Immunocompromised individuals exposed to high levels of mold, or individuals with chronic exposure may become infected.[citation needed] Sinuses and digestive tract infections are most common; lung and skin infections are also possible. Mycotoxins may or may not be produced by the invading mold.
The most common form of hypersensitivity is caused by the direct exposure to inhaled mold spores that can be dead or alive or hyphal fragments which can lead to allergic asthma or allergic rhinitis. The most common effects are rhinorrhea (runny nose), watery eyes, coughing and asthma attacks. Another form of hypersensitivity is hypersensitivity pneumonitis. This is usually the direct result of inhaled spores or fragments in an occupational setting. It is predicted that about 5% of people have some airway symptoms due to allergic reactions to molds in their lifetimes.
Mold-produced mycotoxins
Main article: Mycotoxin
Certain molds excrete toxic compounds called mycotoxins, usually only under specific environmental conditions. Certain mycotoxins can be harmful or lethal to humans and animals when exposure is high enough.
Some mycotoxins cause immune system responses that vary considerably, depending on the individual. The duration of exposure, the frequency of exposure and the concentration of the insult (exposure) are elements in triggering immune system response.
Originally, toxic effects from mold were thought to be the result of exposure to the mycotoxins of some mold species, such as Stachybotrys chartarum. However, studies are suggesting that the so-called toxic effects are actually the result of chronic activation of the immune system, leading to chronic inflammation.[citation needed] Studies indicate that up to 25% of the population have the genetic capability of experiencing chronic inflammation to mold exposure, but only 2% actually experience such symptoms. A 199394 case study based on cases of pulmonary hemorrhage in infants in Cleveland, Ohio originally concluded there was causal relationship between the exposure and the disease. The investigators revisited the cases and established that there was no link to the exposure to S. chartrum and the infants in their homes.[citation needed]
Causes, growing conditions, and remedies
Main articles: Mold growth, assessment, and remediation and Indoor air quality
Mold growth in buildings can lead to a variety of health issues. Various practices can be followed to mitigate mold issues in buildings, the most important of which is to reduce moisture levels that can facilitate mold growth. Removal of affected materials after the source of moisture has been reduced and/or eliminated may be necessary for remediation.
See also
Fungi portal
Building biology
Environmental health
Occupational asthma
Environmental engineering
Ventilation issues in houses
Occupational safety and health
Notes
^ Indoor Environmental Quality: Dampness and Mold in Buildings. National Institute for Occupational Safety and Health. August 1, 2008.
^ "Mold: A Health Hazard (Release #1605-096)". FEMA. November 8, 2005. http://www.fema.gov/news/newsrelease.fema?id=20379. Retrieved 25 September 2007.
^ a b Indian Health Service: Bemidji Area Office of Environmental Health and Engineering Environmental Health Services Section uideline on the Assessment and Remediation of Fungi in Indoor Environments
^ Hardin, BD; Kelman, BJ; Saxon, A (2003). "Adverse human health effects associated with molds in the indoor environment". Journal of occupational and environmental medicine / American College of Occupational and Environmental Medicine 45 (5): 4708. PMID 12762072. edit
^ Ryan KJ; Ray CG (editors) (2004). Sherris Medical Microbiology (4th ed. ed.). McGraw Hill. pp. 6338. ISBN 0838585299.
^ Etzel RA, Montaa E, Sorenson WG, Kullman GJ, Allan TM, Dearborn DG, Olson DR, Jarvis BB, Miller JD. (1998) Acute pulmonary hemorrhage in infants associated with exposure to Stachybotrys atra and other fungi. Archives of Pediatrics and Adolescent Medicine. 152(8):757-62.
References
De Chacon, Jeffrey R.. "Building Hygiene: A New Area Of Concern For Safety Professionals". Best's Safety Directory. http://www.pyramidenvironmentalsystems.com/newsclips/BestsSafetyDirectory2.htm. Retrieved 21 December 2006.
Nelson, Berlin D. "Stachybotrys chartarum: the toxic indoor mold". APSnet. American Phytological Society. http://www.apsnet.org/online/feature/stachybotrys/. Retrieved 19 September 2005.
"Questions and Answers on Stachybotrys chartarum and other molds". Air Pollution & Respiratory Health. National Center for Environmental Health. http://www.cdc.gov/mold/stachy.htm. Retrieved 19 September 2005.
External links
NIH: Environmental Health Perspectives Volume 108, Number 1, January 2000 : Mycotoxins: of Molds and Maladies
MSI Mold and Spore Information: Toxic Mold Symptoms
CDC: http://www.cdc.gov/mold/default.htm
US EPA: Mold Information - U.S. Environmental Protection Agency
US EPA: EPA Publication #402-K-02-003 "A Brief Guide to Mold, Moisture, and Your Home"
NIBS: Whole Building Design Guide: Air Decontamination
NPIC: Mold Pest Control Information - National Pesticide Information Center
Toxic Mold Research Studies
Mycotoxins in grains and the food supply:
http://www.indianacrop.org/Mycotoxin.htm
http://cropwatch.unl.edu/aflatoxin.html
http://agbiopubs.sdstate.edu/articles/FS907.pdf
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