Common Species of
Mold
Aspergillus
Stachybotrys
Cladosporium
Fusarium
Penicillium
Mycotoxins
Note: Different mold species can have
varying health effects, but it is important to remember that
any excessive mold growth needs to be taken care of,
regardless of the species. Any excessive mold growth can lead
to increased allergies, toxicity, and house/building structural
problems.
Aspergillus
spp
Aspergillus
is the most common genus of fungi in our environment with more
than 160 different species of
mold. Sixteen of
these species have been documented as causing human disease.
Aspergillosis is now the 2nd most common
fungal infection requiring hospitalization in the United States
.
Aspergillus
fumigatus. The
most encountered species causing infection. It is seen abundantly in decomposing organic material,
such as self-heating compost piles, since it readily grows at
temperatures up to 55 C. People
who handle contaminated material often develop
hypersensitivity to the spores of Aspergillus
and may suffer severe allergic reactions upon exposure.
Aspergillus
flavus. The 2nd
most encountered fungi in cases of Aspergillus
infection. It is
also known to produce the mycotoxin aflatoxin, one of the most
potent carcinogens known to man. In the 1960s, 100,000 turkey poults in Great Britain
died from ingesting contaminated feed.
Most countries have established levels for aflatoxin in
food. However, the
risks associated with airborne exposure are not adequately
studied and no exposure standards exist.
Aspergillus
niger.
The 3rd most common Aspergillus
fungi associated with disease and the most common of any Aspergillus species in nature due to it’s ability to grow on a
wide variety of substrates. This species may cause a
“fungal ball”, which is a condition where the
fungus actively proliferates in the human lung, forming a
ball. It does so without
invading the lung tissue.
Stachybotrys
chartarum (atra)
This group of molds can thrive on water
damaged, cellulose-rich material in buildings such as sheet
rock, paper, ceiling tiles, insulation backing, wallpaper,
etc. In the majority of
cases where Stachybotrys
is found indoors, water damage has gone unnoticed or ignored
since it requires extended periods of time with increased
levels of moisture for growth to occur.
Stachybotrys is usually black and slimy in appearance. Events of water intrusion that are addressed quickly
tends to support the growth of more xerophilic fungi such as Pencillium
and Aspergillus.
Stachybotrys
is another fungi that has the ability to produce mycotoxins,
ones that are extremely toxic, suspected carcinogens, and
immunosuppressive. Exposure
to these mycotoxins can result through inhalation, ingestion,
and dermal exposure. Symptoms
of exposure include dermatitis, cough, rhinitis, nose bleeds,
cold and flu-like symptoms, headache, general malaise, and
fever.
Cladosporium
spp.
These
genera of mold are pigmented dark green to black in the front,
and black on the reverse with a velvety to powdery texture.
One of the most commonly isolated from indoor and
outdoor air, Cladosporium spp. are found on decaying plants, woody plants, food,
straw, soil, paint, textiles, and the surface of fiberglass
duct liner in the interior of supply ducts.
There are over 30 species in the Cladosporium
genus. The most common
are C. elatum, C. herbarum, C. sphaerospermum, and C. cladosporioides. These
fungi are the causative agents of skin lesions, keratitis,
nail fungus, sinusitis, asthma, and pulmonary infections.
Acute symptoms of exposure to Cladosporium
are edema and bronchiospasms, and chronic exposure may lead to
pulmonary emphysema.
Fusarium
spp.
A
common soil fungus and inhabitant on a wide array of plants,
this fungi is often found in humidifiers and has been isolated
from water-damaged carpets and a variety of other building
materials. Human
exposure may occur through ingestion of contaminated grains
and possibly through the inhalation of spores.
Fusarium spp. are frequently involved with eye, skin, and nail
infections. More
severely it can produce hemorrhagic syndrome (alimentary toxic
aleukia) in humans which is characterized by nausea, vomiting,
diarrhea, dermatitis, and extensive internal bleeding.
Several
species can produce the trichothecene toxins which target the
circulatory, alimentary, skin, and nervous systems.
Vomitoxin is one such tricothecene mycotoxin that has
been associated with outbreaks of acute gastrointestinal
illness in humans. Zearalenone is another mycotoxin produced
by Fusarium.
It is similar in structure to the female sex hormone
estrogen and targets the reproductive organs.
Penicillium
spp.
These
fungi are commonly found in soil, food, cellulose, grains,
paint, carpet, wallpaper, interior fiberglass duct insulation,
and decaying vegetation. Penicillium
may cause hypersensitivity pneumonitis, asthma, and allergic
alveolitis in susceptible individuals.
The genus Penicillium
has several species. The most common ones include Penicillium chrysogenum, Penicillium
citrinum, Penicillium
janthinellum, Penicillium
marneffei, and Penicillium
purpurogenum.
This fungi
has been isolated from patients with keratitis, ear
infections, pneumonia, endocarditis, peritonitis, and urinary
tract infections. Penicillium infections are most commonly exhibited in
immunosuppressed individuals. For
example, P. marneffei
is a fungus abundant in
Southeast Asia
that typically infects patients with AIDS in this area.
Infection with P.marneffei
is acquired via inhalation and initially results in a
pulmonary infection and then spreads to other areas of the
body (lymphatic system, liver, spleen, and bones), and is
often fatal. An indication of infection is the appearance of
papules that resemble acne on the face, trunk, and
extremities.
Penicillim
spp. do have the ability to produce mycotoxins. The
mycotoxin known as Ochratoxin A, which is nephrotoxic and
carcinogenic, may be produced by Penicillium verrucosum. Verrucosidin
is another mycotoxin produced by this fungus that exhibits
neurotoxity. Penicillic
acid is another mycotoxin that is nephrotoxic (causes kidney
and liver damage).
Mycotoxins
During the digestion of substrates, fungi
secrete enzymes into nutrients in order to break down complex
compounds into simpler compounds that can be taken up by the
fungi and used as nutrition.
These digested nutrients produce secondary metabolic
byproducts called mycotoxins that are released to give the
fungi a competitive edge over other microorganisms and fungi.
Unfortunately, mycotoxins can also be incredibly toxic
to humans causing a variety of responses including
cold/flu-like symptoms, sore throats, headaches, nose bleeds,
fatigue, diarrhea, dermatitis, and immune suppression.
Some mycotoxins may also be carcinogenic and
teratogenic. Molds that
have been known to potentially produce these toxins are Acremonium,
Alternaria, Aspergillus, Chaetomium, Cladosporium, Fusarium,
Penicillium, and Stachybotrys.
Even though these molds may potentially
produce mycotoxins, they will not do so unless specific
environmental conditions exist.
Currently, it is unknown exactly what conditions
promote the growth of mycotoxin production and more scientific
research needs to be conducted on this topic for it to be
fully understood.
Types of Mycotoxins
Aflatoxin.
This mycotoxin is primarily produced by Aspergillus
species. It is one
of the most potent carcinogens known to man and has been
linked to a wide array of human health problems.
The FDA has established a maximum allowable level of
total aflatoxin in food commodities of 20 parts per billion
(ppb) and the
maximum level for aflatoxin in milk products is 0.5 ppb.
Ochratoxin.
This mycotoxin is primarily produced by species of Penicillium
and Aspergillus.
It can be damaging to the kidneys / liver, and it is a
suspected carcinogen. There
is also evidence supporting it’s role in impairing immune
system function.
Tricothecene.
The toxin is produced by Stachybotrys spp. and Fusarium
spp and has even been indicated as a potential agent for
use as a biological weapon. One
of the more deadly mycotoxins, if it is ingested in large
amounts it can severely damage the entire digestive tract and
cause rapid death due to internal hemorrhaging.
It has also been implicated in human disease such as
infant pulmonary hemosiderosis.
In 1986, Croft et al., with funding from the Army,
reported chronic inhalation due to mycotoxicosis from
tricothecene exposure in a household in Chicago. For information on
this subject go to: http://gcrc.meds.cwru.edu/stachy/.
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