What Is Mold?

                               

Molds are organisms that are found indoors and outdoors. They are part of the natural environment and play an important role in our ecological system by breaking down and digesting organic material.  Molds are neither plants nor animals.  They are part of the kingdom Fungi.  

Mold is Fungi

The diagram demonstrates the role of fungi in relation to other living organisms.  Fungi are not plants or animals.  Fungi belong to a taxonomic classification, or kingdom, of their own.  Plants convert carbon dioxide directly into carbohydrates for food.  Animals and fungi must find complex carbon in the environment for food.  While animals ingest the food and degrade it internally, fungi excrete chemicals (enzymes) into the environment that degrade the complex carbon into soluble form.

Fungi do not make their own food the way that green plants do.  Fungi get nourishment from other living organisms.  The main role of fungi in the ecosystem is to break down dead materials, such as fallen leaves, trees, insects and animals carcasses.  The same enzymes that assist fungi in breaking down dead materials are what help fungi to damage wooden components in a building.  Molds can damage food, stored goods, and building materials of houses.  

Yeast, mold, mildew and mushrooms are common forms of fungi.  Mold is essentially a description of fungi that grows on surfaces, such as the black substance on a moldy shower wall.  Mold and mildew often refer to the same type of fungi.  All mold is fungi, but not all fungi is mold.

   
Molds grow in many colors, including white. "Black mold" is not a species or specific kind of mold, and neither is "toxic mold."  Sometimes, the news media use the terms "toxic mold" and "black mold" to refer to molds that may produce mycotoxins, or for a specific mold known as Stachybotrys chartarum.  Molds that produce mycotoxins are often referred to as toxigenic fungi.

Molds can multiply by producing microscopic spores (2 to 100 microns [μm] in diameter) similar to the seeds produced by plants.  Many spores are so small, they easily float through the air and can be carried for great distances by even the gentlest breeze.  The number of mold spores suspended in indoor and outdoor air fluctuates from season to season, day to day, and even hour to hour.

No one knows how many species of fungi exist, but estimates range from the tens of thousands to perhaps 300,000 or more.   Some of the more common indoor molds are Penicillium, Aspergillus, Cladosporium and Alternaria.

                                          

        a) Penicillium                b) Stachybotrys                     c) Alternaria              d) Cladosporium

Mold is Everywhere

Mold spores are ubiquitous; they are found both indoors and outdoors. Mold spores cannot be eliminated from indoor environments. Some mold spores will be found floating through the air and on settled dust; however, they will not grow if moisture is not present.

Why Be Concerned?

Mold is not usually a problem indoors—unless mold spores land on a wet or damp spot and begin growing.  As molds grow, they digest whatever they are growing on. Unchecked mold growth can damage buildings and furnishings; molds can rot wood, damage drywall, and eventually cause structural damage to buildings.  Mold can cause cosmetic damage, such as stains, to furnishings. The potential human health effects of mold are also a concern. It is important, therefore, to prevent mold from growing indoors.

Discovering fungi in the indoor environment raises three major concerns:

1)    the potential health effects of exposure to fungi and their byproducts;

2)    the effects of fungal contamination on the structural integrity of a building; and

3)    the negative aesthetic effects fungi can produce both visually and on the human olfactory
       system.

Although the issue of whether exposure to indoor fungi causes adverse health effects is controversial, there is no doubt that a seriously mold-contaminated building can suffer structural damage, and that a foul-smelling, fungus-filled building is aesthetically unpleasing.  Controversies about health effects aside, the latter two reasons are sufficient to merit a Complete Mold Inspection and remediation when an environment is found to have fungal contamination. 

People who have concerns about structural damage or the aesthetic effects of indoor fungi should seek the services of a certified mold inspector.  People who have concerns about health effects of mold exposure should seek the advice of a healthcare professional.

 

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 Negative Health Effects and Mold

 Topics Covered in this Section:

•    Symptoms
•    Infections
•    Mycotoxins
•    ODTS and HP
•    PPE
•    Contaminants

Inhalation exposure to mold indoors can cause negative health effects in some people. Molds produce allergens (substances that can cause allergic reactions), irritants and, in some cases, potentially toxic substances (mycotoxins). Inhaling or touching mold or mold spores may cause allergic reactions in sensitive individuals. Mold does not have to be alive to cause an allergic reaction in some people.

There are some specific groups of people who are potentially more easily or severely affected by mold than the average individual with no sensitivities to mold.  They include infants, children, elderly people, individuals with respiratory conditions (such as allergies and asthma), and people with weakened immune systems (people with HIV/AIDS, chemotherapy patients, and organ transplant recipients).

Sensitive people should avoid areas that are likely to have mold, such as compost piles, cut grass and wooded areas. 

Allergic reactions to mold in buildings do occur for many sensitive people.  However, there is no conclusive evidence that proves that mold in a building directly causes human illnesses.  More research is needed, and mold research has been continuous.  Mold-related exposure and its effects on human health is a complex and emerging science.

Symptoms of Mold Exposure

There are many symptoms of mold exposure.  Current evidence indicates that allergies are the type of diseases most often associated with molds.   An allergic reaction is the most common symptom that could include wheezing and difficulty breathing.

Inhalation of fungal spores, fragments (parts), or metabolites (mycotoxins and volatile organic compounds) from a wide variety of fungi may lead to or exacerbate immunologic (allergic) reactions, cause toxic effects, or cause infections. 

A single or repeated exposure to mold, mold spores, or mold fragments may cause non-sensitive individuals to become sensitive to mold, and repeated exposure has the potential to increase sensitivity. Allergic responses include “hay fever”-like symptoms, such as headache, sneezing, runny nose, irritated eyes, and skin rash (dermatitis). Molds can cause asthma attacks in people with asthma who are allergic to mold.  Fungi in buildings may cause or exacerbate symptoms of allergies, especially in persons who have a history of allergic diseases (such as asthma and rhinitis).  In addition, molds can irritate the eyes, skin, nose, throat, and lungs of individuals, whether or not they are allergic to mold. Other symptoms include nasal and sinus congestion, burning, watery and red eyes, a sore throat, a dry cough, and skin irritation.

These and other symptoms may be associated with exposure to mold. But all of these symptoms may be caused by other exposures or conditions unrelated to mold growth. Therefore, it is important not to assume that mold is the cause of such symptoms.

The effects of mold exposure can be acute or chronic.  An acute effect is an immediate, severe reaction to a large exposure.  A chronic effect may take days, months or years to manifest, and usually comes from small, repeated exposures.

If a person experiences these symptoms only when occupying a particular building, then that person may possibly be experiencing symptoms of mold exposure.

There are four important indoor allergenic molds.  They are Penicillium, Aspergillus, Cladosporium and Alternaria.  Alternaria and Cladosporium are outdoor molds that can be found indoors if the doors or windows of a building are left open and the spores are carried by air currents.

For more detailed information on mold and its health effects, consult a healthcare professional or the state or local health department.

Certified mold inspectors should not offer medical advice to clients.  People with health problems that may be related to mold should seek a physician trained in occupational, environmental or allergy medicine.  Recommend that clients may wish to consult with a healthcare provider regarding any health problems they might be experiencing.

Infections

Only a small group of fungi have been associated with infectious disease.  Aspergillosis is an infectious disease that can occur in immune-suppressed persons.   Health effects in this population can be severe.  Several species of Aspergillus are known to cause aspergillosis.  The most common is Aspergillus fumigatus.  But exposure to this common mold, even in high concentrations, is unlikely to cause infection in a healthy person.

Breathing in mold may also cause hypersensitivity pneumonitis, an uncommon disease that resembles bacterial pneumonia. In addition, mold exposure may result in opportunistic infections in persons whose immune systems are weakened or suppressed. 

There are fungal infections that can affect healthy people.  They are pathogenic fungi sometimes found inside a building:  Blastomyces (which inhabit decaying wood); Coccidioides (found in the southwestern United States); Cryptococcus (in bird droppings); and Histoplasma (in bat guano or droppings).  People without adequate personal protection equipment (PPE) who come in contact with bird or bat droppings, such as may be found in attics, could be at very high risk.  People with compromised immune systems can be seriously affected by fungal infections.

Exposure to fungi associated with bird and bat droppings (Histoplasma capsulatum and Cryptococcus neoformans) can lead to negative health effects in healthy individuals, usually in the form of transient flu-like illnesses.  Severe health effects are primarily encountered in immune-compromised persons.  People with chronic lung illnesses, such as obstructive lung disease, may develop mold infections in their lungs.

Mycotoxins

As molds grow under some conditions, some (but not all) of them may produce potentially toxic byproducts called mycotoxins.   Mycotoxins are fungal metabolites that have been identified as toxic agents.   Some of these mycotoxin-producing molds are commonly found in moisture-damaged buildings.  Exposure to mycotoxins can occur from inhalation, ingestion and/or skin contact.  More than 200 mycotoxins from common molds have been identified, and many more remain to be identified. The amount and types of mycotoxins produced by a particular mold depends on many environmental and genetic factors. 

No one can tell whether a mold is producing mycotoxins just by looking at it.

Many fungi, including species of Aspergillus, Penicillium, Fusarium, Trichoderma, Memnoniella and Stachybotrys chartarum, can produce potent mycotoxins, some of which are identical to the compounds produced by Stachybotrys chartarum.  

There are studies that suggest there is an association between Stachybotrys chartarum and pulmonary hemorrhage/hemosiderosis in infants, generally those under 6 months old.

Toxic substances (mycotoxins) can enter a human body through inhalation, ingestion or skin absorption.  The effects of the toxic substance depend on the chemical or the material, the concentration, the route of entry, and the duration of exposure.

Smoking, alcohol, medication, gender, and existing health problems are all potential factors that can influence the effects of a toxic substance entering a body.

Some mycotoxins are known to affect people, but, for many mycotoxins, little health information is available. Research on mycotoxins is ongoing.

                 
 

PPE

There have been reports linking negative health effects in office workers to offices contaminated with moldy surfaces, as well as symptoms in residents of homes contaminated with fungal growth.  Fatigue, respiratory ailments and eye irritation were typically observed in these cases.
 
Occupants and workers inside buildings can reduce their exposure by proper use of personal protective equipment (PPE), including respirators (minimum N-95), gloves, protective clothing, and goggles.  Personal hygiene and habits are important to reducing exposure for remediation workers.

Contaminants

Although mold is frequently found in damp buildings, it is not the only potential contaminant.  Biological contaminants other than mold, and non-biological contaminants, as well, are often present and may also cause negative health effects. Damp buildings may attract rodents and other pests. Damp or wet building components and furnishings may release chemicals indoors.

Potential contaminants in damp and wet buildings include bacteria, dust mites, cockroaches and other pests, as well as chemicals emitted by damp building materials and furnishings.  For more information on damp buildings and their potential health effects, refer to the Institute of Medicine's 2004 report, "Damp Indoor Spaces and Health."