Mold health hazard



Molds are ubiquitous in nature, and mold spores are a common component of household and workplace dust. However, when mold spores are present in large quantities, they can present a health hazard to humans, typically causing allergic reactions and respiratory problems.

Some molds produce mycotoxins that can pose serious health risks to humans and animals. Exposure to high levels of mycotoxins can lead to neurological problems and in some cases death. Prolonged exposure, e.g. daily workplace exposure, can be particularly harmful. The term toxic mold refers to molds that produce mycotoxins, such as Stachybotrys chartarum, and not to all molds in general.

The health hazards produced by mold have been associated with sick building syndrome.

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.

Health issues and symptoms
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.

Mold spores
Health problems associated with high levels of airborne mold spores include allergic reactions, asthma episodes, irritations of the eye, nose and throat, infections, sinus conjestion, and other respiratory problems. When inhaled, mold spores may germinate, attaching to cells along the respiratory tract and causing further problems in those with weak immune systems.

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.

Mold-produced mycotoxins
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. Serious neurological problems can result from prelonged exposure to mycotoxins. One example of toxic mold is Stachybotrys chartarum which has been associated with sick building syndrome.

Some mycotoxins produced by molds are harmful to humans. . Other mycotoxins cause immune system responses that vary considerably, depending on the individual. The duration of exposure is a key factor in triggering immune system response. Farm animals often die or suffer from mycotoxin poisoning. Mycotoxins resist decomposition from cooking, and remain in the food chain.

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.

Causes / Growing conditions
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.

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 (see also 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).



Both our indoor and outdoor environment have mold spores present. There is no such thing as a mold free environment in the Earth's biosphere.

Spores need three things to grow into mold:


 * Nutrients: Food for spores in an indoor environment is organic matter, often cellulose.
 * Moisture: Moisture is required to begin the decaying process caused by the mold.
 * Time: Mold growth begins between 24 hours and 10 days from the provision of the growing conditions. There is no known way to date mold.

Mold colonies can grow inside building structures. The main problem with the presence of mold in buildings is the inhalation of mycotoxins. Molds may produce an identifiable smell. Growth is fostered by moisture. 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, dust and fabrics. Carpet contains dust made of organic matter such as skin cells. If a house has mold, the moisture may be from the basement or crawl space, a leaking roof, or a leak in plumbing pipes behind the walls. Insufficient ventilation can further enable moisture build-up. The more people in a space, the more humidity builds up. This is from normal breathing and perspiring. Visible mold colonies may 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.

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: Significant mold growth may require professional mold remediation and removal of affected building materials. A conservative strategy is to discard any building materials saturated by the water intrusion or having visible mold growth.
 * Sunlight
 * Ventilation
 * Non-porous building materials
 * Household cleansers - especially bleach

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; see Deutsche Bank Building.

Certain contractors are capable of repairing mold damage - usually by removing the affected areas and eliminating the cause of the excess moisture.

There are also cleaning companies that specialize in Fabric Restoration - a process by which mold and mold spores are removed from clothing to eliminate odor and prevent further mold growth and damage to the garments.