Toxic Mold

Molds are one type of fungi that exist practically everywhere. The purpose of fungi is to break down organic material and recycle them for future use by plants and animals. Fungi include mildews, yeasts, large mushrooms, and mold. Fungi require organic materials in order to form and expand.

Mold is able to grow in damp conditions on a variety of materials such as wood, carpet, insulation, cloth, and all types of food. Mold thrives in damp, moist, or wet surroundings. Molds typically reproduce by releasing their spores into the air and on moist, organic materials. The spores then germinate and begin expanding outwards 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. When mold spores become airborne, once airborne, mold spores can come into contact with human skin or it can be ingested.

If the mold spores are "toxic", they can adversely affect the health of humans. Different mold spores will affect humans differently depending on the type of mold involved, the metabolic byproduct of the mold, as well as the amount of contact and the length of exposure. This also depends on how susceptible the particular human is. Children tend to be affected more 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. Individuals who experience allergic reactions that is often hereditary, who are exposed to mold, mold spores, or mold byproducts may begin to show allergic reactions once they become vulnerable (sensitized) to the particular mold. The reactions can be very mild and temporary reactions or acute or 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 of Medicine:

  • 1 in 5 Americans suffer from allergic rhinitis, the most common chronic disease in humans.
  • 1 in 9 Americans suffer from allergy-related sinusitis.
  • 1 in 10 Americans have allergic-related asthma.
  • 1 in 11 Americans experience allergic dermatitis.
  • Less than 1 in 100 Americans suffer from serious chronic allergic diseases.

These statistics indicate that allergic reactions to mold are extremely common in humans. 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. 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.


This type of reaction to 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 usually found outdoors, growing in soil and dirt. Human contact is usually due to contact with animals.


Exposure to fungus 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. Causing0 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, etc.

Volatile Compounds found in or around homes can irritate mucous membranes. 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, and dizziness.

Reaction to Mold Odors

Certain individuals have extremely strong reactions to the smells given off by molds. Among humans, the ability to detect these odors varies greatly. 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 odors.


Molds also produce secondary metabolites such as antibiotics and mycotoxins (a poisonous substance produced by a fungus). 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. 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 mycotoxins-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), and disrupt various cellular structures such as membranes, they also interrupt important processes, including protein, RNA and DNA production.

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. Many types of mold produce mycotoxins, including some found indoors in contaminated homes and office buildings. A determining factor for mycotoxins that are produced by specific molds usually depends on the materials or organisms that they grow on.

In the past it was believed that dangerous molds were primarily contaminants in foods. This notion is no longer accurate. Recently, researchers have become more concerned with multiple mycotoxins associated with types of mold spores growing in moist indoor environments. Health effects from exposure 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, the following provides possible poor health effects from mycotoxin exposure to multiple molds indoors.

  • Problems with the vascular system. Increased vascular fragility, possibility of hemorrhaging into body tissues. Possible molds include aflatoxin, satratoxin, and torridness.
  • 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 crustaceous 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 weaken 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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