Mold health issues

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

Health problems associated with high levels of airborne mold spores include^{[2][unreliable medical source?]} allergic reactions, asthma episodes, irritations of the eye, nose and throat, sinus congestion, and other respiratory problems. For example, residents of homes with mold are at an elevated risk for both respiratory infections and bronchitis.^[3] When mold spores are inhaled by an immunocompromised individual, some mold spores may begin to grow on living tissue,^[4] attaching to cells along the respiratory tract and causing further problems.^[5][6] 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 infection

Further information: Mycosis

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.^{[7] [8]} 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^[9] such as Penicillium marneffei and Aspergillus fumigatus is a common cause of illness and death among immunocompromised people, including people with HIV, AIDS, and asthma to name a few.^[10][11]

Mold-induced hypersensitivity

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.^[12] The most common effects are rhinorrhea (runny nose), watery eyes, coughing and asthma attacks. Another form of hypersensitivity is hypersensitivity pneumonitis. Exposure can occur at home, at work or in other settings. ^[13][12] It is predicted that about 5% of people have some airway symptoms due to allergic reactions to molds in their lifetimes.^[14]

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

Mycotoxin toxicity

Main article: Mycotoxin

Molds excrete toxic compounds called mycotoxins, secondary metabolites produced by fungi under certain environmental conditions. These environmental conditions affect the production of mycotoxins at the transcription level. Temperature, water activity and pH, strongly influence mycotoxin biosynthesis by increasing the level of transcription within the fungal spore. It has also been found that low levels of fungicides can boost mycotoxin synthesis.^{[15] [16]} Certain mycotoxins can be harmful or lethal to humans and animals when exposure is high enough.^[17][18]

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.

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.^[19]

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

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.

Air

Main articles: Mold growth, assessment, and remediation and Indoor air quality

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. Extensive flooding and water damage can support huge numbers of mold growth. Following hurricanes, homes with greater flood damage, especially those with more than 3 feet of indoor flooding, demonstrated higher levels of mold growth compared with homes with little or no flooding.^{[20] [21]} The aftermath of a hurricane is the worst case scenario, but the concept of water damage supporting widespread mold growth.

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.^[22] Removal of affected materials after the source of moisture has been reduced and/or eliminated may be necessary.^[23] Thus, the concept of mold growth, assessment, and remediation is essential in prevention of mold health issues.

A common issue with mold hazards in the household is the placement of furniture, and the lack of ventilation which this provides certain parts of the wall. The simplest method of avoiding mold in the home is to move the furniture in question.

Adverse respiratory health effects are associated with occupancy in buildings with moisture and mold damage.^[24] Asthma can be aggravated or even induced with exposure to certain fungal species and some fungi cause skin infections such as athletes foot or ring worm.^[22]

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.

Food

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.^[19]

Roughly 25% of the worlds food is contaminated by mycotoxins according to the World Health Organization.^[25] Grains incur considerable losses both in field and storage due to pathogens and insects. Some of the pathogens and resultant mycotoxins reduce the nutritional quality of the product. Mycotoxins are toxigenic fungal compounds that can cause cancer and suppress growth.^[26]

Mycotoxins contaminate grains and other food products across the globe and can significantly impact human health. They can be found growing on grains before harvest and in storage. When ingested, inhaled, or absorbed through skin, mycotoxins may reduce appetite and general performance, and cause sickness or death in some cases.^{[25] [27][28]}

Mold growing in or on field corn and peanuts are the ones most likely to produce aflatoxin.^[19]

Prevention of mold exposure from food is generally to not buy or to discard food that has mold growths on it.^[19] 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.^[19]

Ruminants are considered to be resistant to the toxic effects of mycotoxins, presumably due to their superior mycotoxin-degrading microbes.^[25] This suggests that since mycotoxins are difficult to digest by human microbes due to better degradation by rumen microbes as compared to mono-gastric animals like humans. The carryover of toxins in animal food may have severe consequences on human health.^[29]

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.

See also

Fungi portal

• Building biology
• Environmental health
• Occupational asthma
• Environmental engineering
• Ventilation issues in houses
• Occupational safety and health

Notes

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. ^{[unreliable medical source?]}
3. ^ Fisk, W., Eliseeva, E., & Mendell M. (2010). "Association of residential dampness and mold with respiratory tract infections and bronchitis: a meta-analysis." Environmental Health 9(72).
4. ^ Muller F, Seidler M , “Characteristics of pathogenic fungi and antifungal therapy in cystic fibrosis.” Expert review of anti-infective therapy, 2010, Vol. 8, Issue 8, p. 957-964.
5. ^ Simicic S, Matos T, “Microbiological diagnosis of invasive aspergillosis.” Zdravnisji vestnik-slovanian medical journal. 2010, Vol. 79, Issue 10, p. 716-725.
6. ^ Erol S , Nosocomial aspergillosis: epidemiology and control.” Mikrobiyoloji Bulteni, 2010, Vol. 44, Issue 2, p. 323-338.
7. ^ M Nucci & E Anaissie,"Fusarium Infections in Immunocompromised Patients." Clinical microbiology reviews, October 2007, Vol. 20, Issue 4, p. 695-704.
8. ^ J. Milton Gaviria, Jo‐Anne H. van Burik, David C. Dale, Richard K. Root, and W. Conrad Liles, “Comparison of Interferon‐γ, Granulocyte Colony‐Stimulating Factor, and Granulocyte‐Macrophage Colony‐Stimulating Factor for Priming Leukocyte‐Mediated Hyphal Damage of Opportunistic Fungal Pathogens.” The Journal of Infectious Diseases, 1999, Issue 179, p. 1038–1041.
9. ^ McCormick, A; Loeffler, J; Ebel, F, “Aspergillus fumigatus: contours of an opportunistic human pathogen.” Cellular Microbiology, 2010, Vol. 12, Issue 11, p. 1535-1543.
10. ^ Ben-Ami, R; Lewis, RE; Kontoyiannis, DP, “Enemy of the (immunosuppressed) state: an update on the pathogenesis of Aspergillus fumigatus infection.” British journal of Haematology, 2010, Vol. 150, Issue 4, p. 406-417.
11. ^ Shang, ST; Lin, JC; Ho, SJ, “The Emerging Life-threatening Opportunistic Fungal Pathogen Kodamaea ohmeri: Optimal Treatment and Literature Review.” Journal of microbiology immunology and infection, 2010, Vol. 43, Issue 3, p. 200-206.
12. ^ ^{a b} 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”
13. ^ http://www.nhlbi.nih.gov/health/dci/Diseases/hp/hp_summary.html
14. ^ Hardin, B. D.; Kelman, B. J.; 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): 470–478. PMID 12762072.  edit
15. ^ Reverberi M, Ricelli A, Zjalic S, Fabbri A, Fanelli C, "Natural functions of mycotoxins and control of their biosynthesis in fungi." Appl Microbiol Biotechnology, 2010, Vol. 87, p. 899-911.
16. ^ Bohnert M, Wackler B, and Hoffmeister D, “Spotlights on advances in mycotoxin research.” Applied Microbiology and Biotechnology, 2010, Vol. 87, Issue 1, p.1-7.
17. ^ Ryan KJ; Ray CG (editors) (2004). Sherris Medical Microbiology (4th ed. ed.). McGraw Hill. pp. 633–8. ISBN 0838585299. 
18. ^ 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.
19. ^ ^{a b c d e} United States Food Safety and Inspection Service > Molds On Food: Are They Dangerous? Last Modified: March 4, 2010
20. ^ Barbeau D, Grimsley L, White L, El-Dahr J, Litchtveld M, "Mold Exposure and Health Effects Following Hurricanes Katrina and Rita." Annual Review of Public Health, 2010, Vol. 31, p. 165-178.
21. ^ Shoemaker R & House D, “Sick building syndrome (SBS) and exposure to water-damaged buildings: Time series study, clinical trial and mechanisms.” Neurotoxicology and teratology, 2006, Vol. 28, Issue 5, p. 573-588.
22. ^ ^{a b} Kumar, Manisha Verma, and Rajesh K, “Fungi diversity, their effects on building materials, occupants and control– a brief review.” Journal of Scientific and industrial Research, 2010, Vol. 69, Issue 9, p. 657-661.
23. ^ Wilson S, Holder W, Easterwood K, Hubbard G, Johnson R, Cooley J, and Straus D. “Identification, remediation, and monitoring processes used in a mold-contaminated high school.” Advances in applied microbiology, 2004, Vol. 55, p.409-423.
24. ^ Krieger J, Jacobs D, Ashley P, Baeder A, Chew G, and Dearborn D, “Housing interventions and control of asthma-related indoor biologic agents: a review of the evidence.” Journal of public health management and practice, 2010, Vol. 16, Issue 5, p. S11-S20.
25. ^ ^{a b c} Upadhaya S, Park M, and Ha J, “Mycotoxins and their biotransformation in the rumen: a review.” Asian -Australasian Journal of Animal Sciences, 2010, Vol. 23, Issue 9, p. 1250-1259.
26. ^ Kankolongo M, Hell K, and Nawa I, “Assessment for fungal, mycotoxin and insect spoilage in maize stored for human consumption in Zambia.” Journal of the science of food and agriculture, 2009, Vol. 89, Issue 8, p. 1366-1375.
27. ^ Reddy K, Salleh B, Saad B, Abbas H, Abel C, and Shier W, "An overview of mycotoxin contamination in foods and its implications for human health." Toxin Reviews, 2010, Vol. 29, Issue 1, p. 3-26.
28. ^ He J & Zhou T, “Patented techniques for detoxification of mycotoxins in feeds and food matrices.”Recent patents on food, nutrition & agriculture, 2010, Vol. 2, Issue 2, p. 96-104.
29. ^ Tanuma, Hiramatsu, Mukai, Abe, Kume, Nishiyama and Katsuoka “Case Report. A case of chromoblastomycosis effectively treated with terbinafine. Characteristics of chromoblastomycosis in the Kitasato region, Japan.” 2000, Vol. 43, Issue 1, p. 79-83.

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. Archived from the original on 28 August 2005. http://web.archive.org/web/20050828033934/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
• 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