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Aspergillus fumigatus 01

Light micrograph of the hyphae and spores of the human pathogen Aspergillus fumigatus

Mold health issues are potentially harmful effects of molds.

Molds (also spelled "moulds") are ubiquitous in the biosphere, and mold spores are a common component of household and workplace dust. However, when mold spores are present in abnormally high quantities, they can present a health hazard to humans, potentially causing allergic reactions, producing mycotoxins,[1] or causing fungal infection (mycosis).

Mold-associated conditions Edit

Health problems associated with high levels of airborne mold spores include[2] 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. Also, mold may produce mycotoxins, either before or after exposure to humans, potentially causing toxicity.

Fungal infectionEdit

A serious health threat from mold exposure for immunocompromised individuals is systemic fungal infection (systemic mycosis). 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.

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.

Mold-induced hypersensitivityEdit

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.[3] 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.[3] It is predicted that about 5% of people have some airway symptoms due to allergic reactions to molds in their lifetimes.[4]

The MELISA test (Memory Lymphocyte Immunostimulation Assay), can determine whether a person is allergic to a specific mold.

Hypersensitivity may also be a reaction toward an established fungal infection in allergic bronchopulmonary aspergillosis.

Mycotoxin toxicityEdit

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.[5][6]

Extreme exposure to very high levels of mycotoxins can lead to neurological problems and in some cases death; fortunately, such exposures rarely to never occur in normal exposure scenarios, even in residences with serious mold problems. Prolonged exposure, e.g. daily workplace exposure, can be particularly harmful.

However, not all mycotoxins are harmful, and some are even beneficial to humans, e.g. penicillin.

The health hazards produced by mold have been associated with sick building syndrome, but no validated studies have been able to demonstrate that normal indoor exposures to these common organisms pose a significant threat.

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.

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.

Aflatoxin is an example of a mycotoxin. It is a cancer-causing poison produced by certain fungi in or on foods and feeds, especially in field corn and peanuts.[7]

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 1993–94 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]

Exposure sources and prevention Edit

The main sources of mold exposure are from the indoor air in buildings with substantial mold growth, and from ingestion of food with mold growths.

AirEdit

Main article: Mold growth, assessment, and remediation

Prevention of mold exposure and ensuing health issues include prevention of mold growth in the first place by avoiding a mold-supporting environment such as humid air. It is useful to perform an assessment of the location and extent of the mold hazard in a structure. Various practices of remediation can be followed to mitigate mold issues in buildings, the most important of which is to reduce moisture levels. Removal of affected materials after the source of moisture has been reduced and/or eliminated may be necessary. Thus, the concept of mold growth, assessment, and remediation is essential in prevention of mold health issues.

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.

FoodEdit

Moldy nectarines

Moldy nectarines that were in a refrigerator. The nectarine with black mold is also affecting the nectarine underneath.

Molds that are most often found on meat and poultry are Alternaria, Aspergillus, Botrytis, Cladosporium, Fusarium, Geotrichum, Monilia, Manoscus, Mortierella, Mucor, Neurospora, Oidium, Oosproa, Penicillium, Rhizopus and Thamnidium.[7]

Mold growing in or on field corn and peanuts are the ones most likely to produce aflatoxin.[7]

Prevention of mold exposure from food is generally to not buy or to discard food that has mold growths on it.[7] Also, mold growth in the first place can be prevented by the same concept of mold growth, assessment, and remediation that prevents air exposure. In addition, it is especially useful to clean the inside of the refrigerator, and having clean dishcloths, towels, sponges and mops.[7]

History Edit

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.

See also Edit

NotesEdit

  1. Indoor Environmental Quality: Dampness and Mold in Buildings. National Institute for Occupational Safety and Health. August 1, 2008.
  2. "Mold: A Health Hazard (Release #1605-096)". FEMA. November 8, 2005. http://www.fema.gov/news/newsrelease.fema?id=20379. Retrieved 25 September 2007. 
  3. 3.0 3.1 Indian Health Service: Bemidji Area Office of Environmental Health and Engineering Environmental Health Services Section “Guideline on the Assessment and Remediation of Fungi in Indoor Environments”
  4. 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): 470–8. PMID 12762072.  edit
  5. Ryan KJ; Ray CG (editors) (2004). Sherris Medical Microbiology (4th ed. ed.). McGraw Hill. pp. 633–8. ISBN 0838585299. 
  6. Etzel RA, Montaña 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.
  7. 7.0 7.1 7.2 7.3 7.4 United States Food Safety and Inspection Service > Molds On Food: Are They Dangerous? Last Modified: March 4, 2010

ReferencesEdit

External linksEdit


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