ALL ABOUT MOLD
From
Wikipedia, the free encyclopedia
Toxic
mold
Molds
are ubiquitous in nature, and mold
spores are a common component of household dust.
The term toxic mold is sometimes used to refer to mold-related
indoor air quality problems.
Molds excrete liquids or gases as defecatory matter; not all can be
detected by smell. Some molds generate toxic liquid or gaseous
compounds, called mycotoxins. Of
these molds, some only produce mycotoxins under specific growing
conditions. Mycotoxins are harmful or lethal to humans and animals
when exposure is high enough. Exposure to significant quantities of
mold spores can cause toxic/allergic reactions.
Although
this home suffered only minor
exterior damage from
Hurricane Katrina,
small leaks and inadequate air flow
permitted this mold infestation.
Growing conditions
For
significant mold growth to occur, there must be a source of water
(which could be invisible humidity), a source of food, and a substrate capable of
sustaining growth. Common building materials, such as plywood,
drywall, furring strips, carpets, and carpet padding are food for
molds. In carpet, invisible dust is the food source
(dust
mites). After a single
incident of water damage occurs in a building, molds grow inside
walls and then become dormant until a subsequent incident of high
humidity; this illustrates how mold can appear to be a sudden
problem, long after a previous flood or water incident that did not
produce a mold-related problem. The right conditions re-activate
mold. Studies also show that mycotoxin levels are perceptibly
higher in buildings that have once had a water incident (source
CMHC).
The house dust
mite; its feces and
chitin are
common allergens around the home
History
Since
Biblical times it has been known that indoor mold growth can be a
health hazard. (See Leviticus 14:39-47.) 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.
In the 1970s, building construction techniques changed in response to the
energy
crises. As a result, homes and
buildings became more air-tight. Also, cheaper materials such
as drywall came
into common use. This combination of increased moisture and
suitable substrates contributed to increased mold growth inside
buildings.
Today, the agriculture industry keeps a close eye on mold and
mycotoxin levels in grains in order to prevent the contamination of
animal feed and human food supplies. 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 died before the food
could be recalled.
Causes
Because common building materials are capable of
sustaining mold growth, and mold spores are ubiquitous, mold growth
in an indoor environment is typically related to an indoor water or
moisture problem. Leaky roofs, building maintenance problems, or
indoor plumbing problems can lead to mold growth inside homes,
schools, or office buildings. Another common source of mold growth
is flooding.
Common molds
- Aspergillus
- Cephalosporium
- Cladosporium
- Cryptococcus
- Fusarium
- Harposporium
- Mucro
- Ostracoderma
- Penicillium
- Rhodotorula
- Trichoderma
Symptoms
Human bodies can tolerate mycotoxins in small quantities. At what point they constitute a health hazard depends on each individual. Immune system reactions vary; the health effects of mycotoxin exposure include chronic fatigue and irritability, flu-like symptoms, respiratory problems, headaches, cognitive problems, and skin problems. A stressed immune system results in a weakened individual.
Another serious health threat from mold exposure is systemic fungal infection. Immunocompromised individuals exposed to high levels of mold, or individuals with chronic exposure paired with mycotoxin exposure may become infected. Sinuses and digestive tract infections are most common; lung and skin infections are also possible. Alcohol and mycotoxin production may result from the fungal growth, leading to myriad symptoms. Sudden food allergies and digestive problems can mislead diagnosis. Treatment can be long-term (many years). Systemic infection may be of the environmental mold itself, or by other common food-related molds consumed under a weakened immune system. A weakened immune system may also give rise to opportunistic infections, for example bacterial infection.
Environmental illnesses can be difficult for healthcare practitioners to diagnose. Those who are living in houses contaminated by the mold may not be able to smell any odor and may be unaware that the problem exists.
Remedies
The first step in solving an indoor mold problem is stopping the source of moisture. Next is to remove the mold growth. Common remedies for small occurrences of mold include:
- Sunlight
- Ventilation
- Non-porous building materials
- Household cleansers
Mold
growing on carpet
2006-03-13.
Same
mold as above on carpet, 4 months later -
2006-07-09.
Mold
on a liquid surface
Mold
colonies are commonly seen in damp areas such as basements and
bathrooms, and can also grow inside building structures. Growth is
fostered by moisture, especially following floods and water leaks.
Mold may produce an identifiable smell. However, the main problem
with the presence of mold in buildings is the inhalation of
mycotoxins. After a flood or major leak, mycotoxin levels are
higher in the building even after it has dried out (source:
CMHC).
Food sources for molds in buildings include
cellulose-based
materials, such as wood, cardboard, and the paper facing on both
sides of drywall, and all other kinds of
organic matter,
such as soap and dust. Carpet contains dust and other organic
matter.
Indoor Mold needs four things to grow:
(1)
Spores: Both
our indoor and outdoor environment have mold spores present. There
is no such thing as a mold free environment.
(2) Nutrients: The
Spores need food, and in the indoor environment these are normally
cellulose materials (wood, dust, fabrics, cardboard, paper,
etc.)
(3) Moisture Moisture
is required to begin the decaying process of the cellulose material
by the mold.
(4) Time: Mold
growth typically begins between 24 hours and 10 days from the
provision of the growing conditions. There is no way to date
mold.
If
a house has excessive mold, there is usually too much moisture in
the house, possibly from the basement, a leaking roof, or leaks
from plumbing pipes behind the walls. Insufficient ventilation can
also enable moisture build-up. The more people in a space, the more
humidity builds up. This is from normal breathing and perspiring.
Mold colonies often form where ventilation is poorest, and on
perimeter walls, because they are coolest, thus closest to
the
dew
point.
If there are mold problems in a house only during certain times of
the year, then it is probably either too air-tight, or too drafty.
Mold problems occur in airtight homes more frequently in the warmer
months (when humidity reaches high levels inside the house, and
moisture is trapped), and occur in drafty homes more frequently in
the colder months (when warm air escapes from the living area into
unconditioned space, and condenses). If a house is humidified
artificially during the winter, this can create conditions
favorable to mold. Moving air may prevent mold from growing since
it has the same desiccating effect as lowering humidity.
There are many ways to prevent mold growth; see
ventilation issues in houses.
In extreme cases of mold growth in buildings, it may be easier to
condemn the building rather than clean the mold to safe
levels.