Molds are but one type of
fungi that exist in nearly every location across the globe.
The purpose of fungi is to break down organic material and recycle
them for future use by plants and animals. The family of fungi includes
mildews, yeasts, large mushrooms, and mold. Fungi require organic
materials in order to form and expand.
When damp conditions are present,
mold is able to grow on such diverse materials as wood, carpet,
insulation, cloth, and all types of food. Mold thrives in damp,
moist, or wet surroundings, frequently in areas where humans exist.
Molds typically reproduce through their spores that are released
into the air and land on moist, organic materials. The spores then
germinate and began expanding out in elaborate networks. The factors
that determine the rate of this growth include amount of moisture,
type of food or organic material, temperature, and many others.
Humans often come in contact with
molds in moist areas in or around their homes or when mold spores
become airborne. These airborne mold spores can come into contact
with humans either through the skin or when ingested.
If the mold spores are "toxic",
they can adversely affect the health of humans. The effect on humans
will depend on the type of mold involved, the metabolic byproduct
of the mold, as well as how much contact there is and the length
of exposure, as well as the level of susceptibility of the human
victim. This last factor is important for children who can be affected
much more easily than adults.
The ill effects of molds generally
break down into 4 categories that include allergies, infections,
irritations, and toxicities.
Allergies are probably the most common reaction to contact with
molds. Atopic individuals (those who experience allergic reactions
that is often hereditary) who are exposed to mold, mold spores,
or mold byproducts may manifest allergic reactions once they become
vulnerable (sensitized) to the particular mold. The reactions can
run the spectrum, from very mild and temporary reactions to acute,
chronic illness. Of course, molds are simply one of the causes of
indoor allergens. Other common causes include dust mites, cockroaches,
effluvia from domestic pets and other microorganisms (molds are
included in this category).
However, according to The Institute
- 1 in 5 Americans suffer from allergic
rhinitis, the most common chronic disease in humans.
- 1 in 9 Americans suffer from allergy-related
- 1 in 10 Americans have allergic-related
- 1 in 11 Americans experience allergic
- Less than 1 in 100 Americans suffer
from serious chronic allergic diseases.
These statistics indicate that allergic
reactions are extremely common in humans. Often times, the specific
cause of the allergies is in question. Recently, the existence of
mold in homes and workplaces has cropped up as a very real possibility
as the cause of some of these allergic reactions.
Many different types of molds can
put their spores and byproducts into the air, but only a few purified
mold allergens are available for allergy tests. Atopic individuals
can become sensitized to certain molds, but this may not always
be cited by a health care professional as a mold-related allergy.
A positive mold allergy test indicates that an individual is susceptible
to a specific allergen, but testing negative doesn't necessarily
rule out mold allergy for atopic individuals.
This type of reaction from indoor mold is fairly rare, occurring
primarily in those individuals who are susceptible. Aspergillus
types of mold have been known to be pathogenic (a disease producing
microorganism) For instance, Aspergillus fumigatus (A.
fumigatus) is a fairly weak pathogen thought to cause infections
in vulnerable individuals. A. fumigatus is also fairly commonly
implicated in ABPA and allergic fungal sinusitis.
Other fungi that cause infection
include Coccidioides, Histoplasma, and Blastomyces. However,
these fungi are rarely found indoors, growing instead in soil and
dirt. Human contact is usually due to contact with animals.
Fungal exposure can also come from any volatile compounds (VOCs)
that a fungi/mold creates through primary or secondary metabolism
that then becomes airborne. (Primary metabolic processes are those
necessary to sustain the life of an organism.) These volatile compounds
may be constantly created as the fungus consumes its food source
during the primary metabolic process. VOCs can irritate the mucous
membranes of the eyes and respiratory system.
Fungi that consume certain organic
sources can release highly toxic gases. For instance, a fungus that
grows on wallpaper often releases toxic gas arsine directly from
the wallpaper that contains arsenic pigments. Thus, fungi and molds
can release dangerous materials when they break down the host material.
This can cause mucous membrane irritation in sensitized individuals.
Fungal volatile compounds may impact
the "common chemical sense" which senses pungency and responds to
it. This sense is primarily associated with the trigeminal nerve.
The sensory and motor nerves respond to pungency by trying to hold
the breath, discomfort, or through sensations such as itching, burning,
and skin crawling. Changes in sensation, swelling of mucous membranes,
constriction of respiratory smooth muscle, or dilation of surface
blood vessels may be part of fight or flight reactions in response
to trigeminal nerve stimulation. Reactions often include a reduced
attention level, general disorientation, lowered reflex time, dizziness,
Volatile Compounds found in or around
homes can be responsible for mucous membrane irritants. It is thought
that fungi can add to the already existing compounds when breaking
down certain organic substances. A mold-contaminated building may
have a significant contribution from its fungal contaminants that
is added to common VOCs---building materials, paints, plastics and
cleaners. VOCs in general can result in symptoms that
include lowered attention span, headaches, lack of concentration,
Reaction to Mold Odors
Some individuals have very strong reactions to the smells given
off by molds. Among humans, there is a high degree of variation
in ability to detect these odors. Certain individuals can detect
low levels of VOCs, while others can only detect relatively high
levels. Those individuals who are particularly susceptible to mold
odors may react with headache, nasal stuffiness, nausea or even
vomiting. Asthmatics often exhibit symptoms when exposed to certain
Molds also produce secondary metabolites such as antibiotics and
mycotoxins (a poisonous substance produced by a fungus). Sometimes
it is possible to isolate antibiotics from the molds themselves
in order to utilize some of their properties in fighting infections.
Secondary metabolisms are not necessary for maintaining the existence
of a mold---either by creating energy or synthesizing structural
components, informational molecules or enzymes. They do, however,
function to provide molds with advantages over other mold and bacteria
and are toxic to certain plant and human cells.
Toxic conditions exist when a human
has exposure to these mycotoxins---either through ingesting mycotoxin-containing
mold spores or with skin contact to mold itself. Mycotoxins are
nearly all cytotoxic (substances produced by microorganisms that
are toxic to individual cells), which disrupt various cellular structures
such as membranes, and interrupt important processes, including
protein, RNA and DNA synthesis.
Mycotoxins vary in how dangerous
they are for humans. Mycotoxins pose a threat to larger organisms
not because they are specifically targeting them, but rather because
these large organisms inadvertently come across the byproduct of
the competing molds all vying for the same ecological niche. Numerous
mold types produce mycotoxins, including some found indoors in contaminated
homes and office buildings. Another factor that determines the mycotoxins
that are produced by specific molds usually depends on the materials
or organisms that they grow on.
It used to be thought that dangerous
molds were primarily contaminants in foods. This notion is quickly
changing. Recently, researchers have become more concerned with
multiple mycotoxins that derive from many types of mold spores growing
in moist indoor environments. Health effects from exposures
to such mold mixtures can differ from those related to single mycotoxins
in controlled laboratory exposures. Although it is difficult
to predict how exposure to multiple toxigenic molds can affect an
individual (they can synergize the effects), the following provides
possible poor health effects from mycotoxin exposure to multiple
- Problems with the vascular system.
Increased vascular fragility, possibility of hemorrhaging into
body tissues. Possible molds include aflatoxin, satratoxin, roridins.
- Problems with digestive system.
Diarrhea, vomiting, intestinal hemorrhage, liver effects (such
as necrosis and fibrosis). Aflatoxin results in deleterious effects
on mucous membranes.
- Problems with respiratory system.
Including respiratory distress, and bleeding from the lungs.
- Problems with nervous system.
Tremors, lack of coordination, depression, and headaches.
- Problems with cutaneous system.
Symptoms include rash, burning sensation, and sloughing of skin.
- Problems with urinary system.
- Problems with reproductive system.
Including infertility, changes in reproductive cycles, etc.
- Many mycotoxins can produce changes
or a weakening of the immune system.
Unfortunately, not all types or species
of molds have been tested for the presence of mycotoxins. The production
of toxins varies according to the type of mold, the substrate on
which it grows, and seasons of the year.
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