Stachybotrys,spores (left) and structure (right)Mold Classes & Classes of Mold-Related Illness

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Classes of harmful or irritating mold & mold related illnesses:

This document lists classes or types of mold (harmless to toxic) and names types of common mold-related illness. We provide: definitions of cosmetic mold, allergenic mold, & pathogenic mold - three levels of concern.

Definitions of & Explanations of Mycotoxins, Mycoses, Mycotoxicoses. What's the difference between fungal mycoses & fungal mycotoxicoses & what are the usual pathways of infection? Comparing two types of Mycoses: primary pathogens vs opportunistic pathogens. Examples & Symptoms of Mycotoxicoses.

We explain the types and classes of mold or fungal related illnesses, and we provide definitions and comparisons among mold-illness terms that otherwise can lead to confusion: cosmetic mold, allergenic mold, toxic mold, toxic black mold, pathogenic mold, mycoses or mycosis, mycotoxicoses or mycotoxicosis, and primary versus opportunistic pathogens.

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

Classes or Types of Mold - by Degree of Potential Effect of Mold on Humans

Black mold under the microscope (C) Daniel FriedmanArticle Contents

Cosmetic mold

"Cosmetic mold" refers to mold genera or species which are unlikely to be a health hazard nor to cause damage to the building structure.

Photograph: typical cosmetic bluestain mold on new framing lumber, floor joists - © Daniel FriedmanA common example found on framing lumber, often from time of construction, is black mold in the Ophistomacae group including Ophistoma sp. and Ceratocystis sp. which are commonly known as "blue stain" fungi.

If these are present in the finished living space it may be appropriate to clean and coat the stained areas for cosmetic reasons.

More costly measures are unlikely to be justified.


Allergenic mold

"Allergenic mold" is not normally dangerous in small quantities, but can be a problem for people who are particularly allergic to mold or who have asthma. In large quantities it is more likely to be a problem for these individuals.

Allergenic mold can be cleaned or removed by people who are not personally mold-sensitive by using ordinary cleaning methods and while wearing appropriate respiratory protection and gloves.

People who are particularly mold sensitive should avoid working with or disturbing moldy materials which might cause a reaction or increase their sensitivity. Where large areas of this mold are involved, e.g. in excess of 30 sq.ft., professional cleaning is likely to be needed.

Common Mold-Allergic Responses

Examples of Mold Related Illnesses

Pathogenic or "Infectious" Mold - Mycoses

Mold in this group can cause infections in humans, including not only people at particular risk (such as those having a compromised immune system) but also people who are normal and healthy. In general, fungal or mold-related illnesses that are classed as mycoses result from a fungus that actually grow on or in human (or other animal) tissues.

Please also read about the difference between fungal mycoses & fungal mycotoxicoses in DEFINITIONS OF & EXPLANATIONS OF MYCOTOXINS, MYCOSES, MYCOTOXICOSES (found below).

In most general terms we often include this group in our "Toxic mold" category below, but properly it is a separate group.

Toxic Mold - distinguished from Pathogenic Mold

Toxic mold can present serious health risk to humans or animals by producing or containing chemical poisons. Unlike the pathogenic molds discussed above, Health effects from toxic mold exposure may be temporary irritation or more serious longer term illness, immunosuppression, neurological disorders, or cancer.

Mycotoxins can be produced by or are contained some fungal spores and may remain present in the fungal material (potentially also in fungal hyphae) even if the mold spores are not viable - i.e. have been "killed" by a chemical disinfectant (bleach).

When a toxic mold has been identified as contaminating a building, advice from a mold professional is appropriate. The average homeowner should not attempt to clean up this type of contamination.

The Toxic Black Mold Mistake - inaccurate reports, misspending, building cleaning mistakes

Black mold on drywall (C) Daniel Friedman

Watch out: What is misleading, in fact in our opinion downright dangerous about the term "toxic black mold" is that people may be misled to believe that only black mold is harmful.

Not only is this not at all the case, but in many building mold investigation cases dark colored molds (which may be black, dark brown, or other dark colors) are selected for sampling, resulting in important errors when assessing the risk of building mold contamination:

Black mold under the microscope (C) Daniel Friedman

Aspergillus mold under the microscope (C) Daniel Friedman

Clear Definitions of & Explanations of Mycotoxins, Mycoses, Mycotoxicoses

What's the difference between fungal mycoses & fungal mycotoxicoses & what are the usual pathways of infection?

Actually our use of the prefix "fungal" is redundant as both mycoses and mycotoxicoses originate in the fungal kingdom.

Mycoses are pathogens that attack healthy or weakened individuals, as we distinguish in a moment, and in seriousness range from an irritating skin fungal infection to potentially fatal invasion of bodily tissues in the lung (aspergillosis) or even the head and brain.

What characterizes fungal mycosis is that the fungus is actually growing on or in the tissues or organs of the person or animal affected. (Both athlete's foot (tinea) and aspergillosis involve such fungal growth on or in a person's tissues - a foot or a lung for example).

The usual path of infection for mycoses is from breathing in spores or by skin contact.

Mycotoxicoses are examples of “poisoning by natural means” and thus are analogous to the pathologies caused by exposure to pesticides or heavy metal residues.

In other words, unlike a mycosis (fungus growing in an organ), a mycotoxicosis acts on a person other animal by producing a chemical that itself is a poison. [1]

The usual path of infection for mycotoxicoses are eating contaminated food but breathing in spores or skin contact infections also occur.

Comparing two types of mycoses: primary pathogens vs opportunistic pathogens

A more accurate characterization of the Fifth Kingdom (molds) with respect to mold related illness (mycoses) start by dividing the causing pathogenic fungi into two categories

Examples & Symptoms of Mycotoxicoses

The most important mycotoxins that may affect humans or other animals are aflatoxin, citrinin, ergot akaloids, fumonisins, ochratoxin A, patulin, trichothecenes, and zearalenone.

These poisons may enter the body by eating contaminated food (most common means) but also by inhalation or skin contact (such as some of our clients who report severe and some protracted medical symptoms that ensued after unusually high exposure to Stachybotrys chartarum or Memnoniella echinata [the author] during moldy building demolition or cleanup.) [1]

The symptoms of a mycotoxicosis depend on the type of mycotoxin; the amount and duration of the exposure; the age, health, and sex of the exposed individual; and many poorly understood synergistic effects involving genetics, dietary status, and interactions with other toxic insults.

Thus, the severity of mycotoxin poisoning can be compounded by factors such as vitamin deficiency, caloric deprivation, alcohol abuse, and infectious disease status. In turn, mycotoxicoses can heighten vulnerability to microbial diseases, worsen the effects of malnutrition, and interact synergistically with other toxins. [1] J.W. Bennett and M. Klich

Definition of mycotoxin

A mycotoxin is a poison produced by a fungus. "Poison" as used here is properly understood to cause illness or death to a human or
other animal.

Mycotoxins are made by fungi and are toxic to vertebrates and other animal groups in low concentrations. [1

Quoting from Bennett and Kilch in Clinical Microbiology in an authoritative article that itself cites 290 expert sources:

Mycotoxins are secondary metabolites produced by microfungi that are capable of causing disease and death in humans and other animals.

Because of their pharmacological activity, some mycotoxins or mycotoxin derivatives have found use as antibiotics, growth promotants, and other kinds of drugs; still others have been implicated as chemical warfare agents. ...

While all mycotoxins are of fungal origin, not all toxic compounds produced by fungi are called mycotoxins. The target and the concentration of the metabolite are both important. Fungal products that are mainly toxic to bacteria (such as penicillin) are usually called antibiotics.

Molds (i.e., microfungi) make mycotoxins; mushrooms and other macroscopic fungi make mushroom poisons. The distinction between a mycotoxin and a mushroom poison is based not only on the size of the producing fungus, but also on human intention. Mycotoxin exposure is almost always accidental. In contrast, with the exception of the victims of a few mycologically accomplished murderers, mushroom poisons are usually ingested by amateur mushroom hunters who have collected, cooked, and eaten what was misidentified as a delectable species.

Mycotoxins are not only hard to define, they are also challenging to classify.

Due to their diverse chemical structures and biosynthetic origins, their myriad biological effects, and their production by a wide number of different fungal species, classification schemes tend to reflect the training of the person doing the categorizing. Clinicians often arrange them by the organ they affect.

Thus, mycotoxins can be classified as hepatotoxins, nephrotoxins, neurotoxins, immunotoxins, and so forth.

Cell biologists put them into generic groups such as teratogens, mutagens, carcinogens, and allergens.

Organic chemists have attempted to classify them by their chemical structures (e.g., lactones, coumarins); biochemists according to their biosynthetic origins (polyketides, amino acid-derived, etc.); physicians by the illnesses they cause (e.g., St. Anthony's fire, stachybotryotoxicosis), and mycologists by the fungi that produce them (e.g., Aspergillus toxins, Penicillium toxins). None of these classifications is entirely satisfactory. - [1] J.W. Bennett and M. Klich

Not all fungi produce mycotoxins and those that do don't always do so

Not all fungi produce mycotoxins, and even fungi that do produce them do not always do so - depending on growing conditions such as what particular "food" substrate the fungus is growing upon.

Interestingly, and part of our objection to "killing" mold as a mold remedy, is that some mold spores that contain mycotoxins continue to do so even after the a mold spore been rendered unable to "grow" further. Thus a "dead" mold spore can still be harmful to humans. (Fungal products that are toxic to plants are called phytotoxins.)


A More Broad Set of Categories of Building Mold

A more complete categorization that helps people understand the risk associated with all types of mold growths found in buildings on building surfaces would use the following categories, all of which are discussed in thios article: [3][4][5]





PATHOGENIC, TOXIC, OR "INFECTIOUS" MOLD - here we include both mycoses and mycotoxicoses

Attempts to "kill" mold using bleach or fungicidal disinfectants are improper

Attempts to "kill" mold, such as by using bleach, are inappropriate and ineffective since some spores can be dangerous even if they have been made not viable.

This is why simply spraying or "bleaching" a moldy surface with a disinfectant is not effective. Actual cleaning or removal of contaminated materials is the appropriate step when fungal-contamination is found indoors.

Effective mold cleanup is possible - Here's What to Do

An effective mold cleanup is entirely possible and often leaves a building cleaner than when it was originally constructed. A mold clearance test following professional remediation is used to assure that the cleanup has been effective.

But unless the original causes of mold growth are corrected (usually leaks and building water entry) the problem is likely to recur. Finally, the object of mold cleanup is not normally to produce a sterile indoor environment.

Mold is normal material found in outdoor air and is present virtually everywhere.

The cleaning objective is to clean up or "remove" problematic levels of allergenic or toxic mold and to bring the remaining level of common fungal spores in a building down to levels commonly found in buildings which have not suffered leaks, water entry, and problematic mold growth.

Reference: some of the notes from this page are paraphrased from a guest column, "Understanding the Health Effects of Mold," by Dr. Ajit S. Arora, MD, PhD, appearing in AIHA's magazine "The Synergist," September 2003,

See our main website (below) for very important additional information such as mold testing, cleanup and mold remediation guideline resources.


Continue reading at MOLD CONTAMINATION LEVELS or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.


Or see MOLD EXPOSURE STANDARDS definitions of "problematic levels" of mold.

Or see MOLD DOCTORS - ENVIRONMENTAL MEDICINE for help in finding a physician specializing in mold exposure, mold related illness, or environmental medicine.

Or see MOLD RELATED ILLNESS for a complete, detailed list of health complaints associated with mold exposure.

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