Fw: Aerotech Laboratories' IAQ Tech Tip #46 - Is Indoor Mold Contamination a Threat to Health? Part 1

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> Aerotech Laboratories' IAQ Tech Tip #46 - Is Indoor Mold Contamination a

Threat to Health? Part 1 of a 2 Part Series

>

> The following article is part one of a two-part series article that was

written by Harriet M. Ammann, Ph.D., D.A.B.T. She is a senior toxicologist

for Washington State Department of Health, Office of Environmental Health

Assessments. The second half of this article will appear in IAQ Tech Tip

#47.

>

> The Fungus Among Us

> Molds, a subset of the fungi, are ubiquitous on our planet. Fungi are

found in every ecological niche, and are necessary for the recycling of

organic building blocks that allow plants and animals to live. Included in

the group " fungi " are yeasts, molds and mildews, as well as large mushrooms,

puffballs and bracket fungi that grow on dead trees. Fungi need external

organic food sources and water to be able to grow.

>

> Molds

> Molds can grow on cloth, carpets, leather, wood, sheet rock, insulation

(and on human foods) when moist conditions exist (Gravesen et al., 1999).

Because molds grow in moist or wet indoor environments, it is possible for

people to become exposed to molds and their products, either by direct

contact on surfaces, or through the air, if mold spores, fragments, or mold

products are aerosolized.

>

> Many molds reproduce by making spores, which, if they land on a moist food

source, can germinate and begin producing a branching network of cells

called hyphae. Molds have varying requirements for moisture, food,

temperature and other environmental conditions for growth. Indoor spaces

that are wet, and have organic materials that mold can use as a food source,

can and do support mold growth. Mold spores or fragments that become

airborne can expose people indoors through inhalation or skin contact.

>

> Molds can have an impact on human health, depending on the nature of the

species involved, the metabolic products being produced by these species,

the amount and duration of individual's exposure to mold parts or products,

and the specific susceptibility of those exposed.

>

> Health effects generally fall into four categories. These four categories

are allergy, infection, irritation (mucous membrane and sensory), and

toxicity.

>

> Allergy

> The most common response to mold exposure may be allergy. People who are

atopic, that is, who are genetically capable of producing an allergic

response, may develop symptoms of allergy when their respiratory system or

skin is exposed to mold or mold products to which they have become

sensitized. Sensitization can occur in atopic individuals with sufficient

exposure.

>

> Allergic reactions can range from mild, transitory responses, to severe,

chronic illnesses. The Institute of Medicine (1993) estimates that one in

five Americans suffers from allergic rhinitis, the single most common

chronic disease experienced by humans. Additionally, about 14% of the

population suffers from allergy-related sinusitis, while 10 to 12% of

Americans have allergically-related asthma. About 9% experience allergic

dermatitis. A very much smaller number, less than one percent, suffer

serious chronic allergic diseases such as allergic bronchopulmonary

aspergillosis (ABPA) and hypersensitivity pneumonitis (Institute of

Medicine, 1993). Allergic fungal sinusitis is a not uncommon illness among

atopic individuals residing or working in moldy environments. There is some

question whether this illness is solely allergic or has an infectious

component. Molds are just one of several sources of indoor allergens,

including house dust mites, cockroaches, effluvia from domestic pets (birds,

rodents, dogs, cats) and microorganisms (including molds).

>

> While there are thousands of different molds that can contaminate indoor

air, purified allergens have been recovered from only a few of them. This

means that atopic individuals may be exposed to molds found indoors and

develop sensitization, yet not be identified as having mold allergy. Allergy

tests performed by physicians involve challenge of an individual's immune

system by specific mold allergens. Since the reaction is highly specific, it

is possible that even closely related mold species may cause allergy, yet

that allergy may not be detected through challenge with the few purified

mold allergens available for allergy tests. Thus a positive mold allergy

test indicates sensitization to an antigen contained in the test allergen

(and perhaps to other fungal allergens) while a negative test does not rule

out mold allergy for atopic individuals.

>

> Infection

> Infection from molds that grow in indoor environments is not a common

occurrence, except in certain susceptible populations, such as those with

immune compromise from disease or drug treatment. A number of Aspergillus

species that can grow indoors are known to be pathogens. Aspergillus

fumigatus (A. fumigatus) is a weak pathogen that is thought to cause

infections (called aspergilloses) only in susceptible individuals. It is

known to be a source of nosocomial infections, especially among

immune-compromised patients. Such infections can affect the skin, the eyes,

the lung, or other organs and systems. A. fumigatus is also fairly commonly

implicated in ABPA and allergic fungal sinusitis. Aspergillus flavus has

also been found as a source of nosocomial infections (Gravesen et al.,

1994).

>

> There are other fungi that cause systemic infections, such as

Coccidioides, Histoplasma, and Blastomyces. These fungi grow in soil or may

be carried by bats and birds, but do not generally grow in indoor

environments. Their occurrence is linked to exposure to wind-borne or animal

borne contamination.

>

> Mucous Membrane and Trigeminal Nerve Irritation

> A third group of possible health effects from fungal exposure derives from

the volatile compounds (VOC) produced through fungal primary or secondary

metabolism, and released into indoor air. Some of these volatile compounds

are produced continually as the fungus consumes its energy source during

primary metabolic processes. (Primary metabolic processes are those

necessary to sustain an individual organism's life, including energy

extraction from foods, and the syntheses of structural and functional

molecules such as proteins, nucleic acids and lipids). Depending on

available oxygen, fungi may engage in aerobic or anaerobic metabolism. They

may produce alcohols or aldehydes and acidic molecules. Such compounds in

low but sufficient aggregate concentration can irritate the mucous membranes

of the eyes and respiratory system.

>

> Just as occurs with human food consumption, the nature of the food source

on which a fungus grows may result in particularly pungent or unpleasant

primary metabolic products. Certain fungi can release highly toxic gases

from the substrate on which they grow. For instance, one fungus growing on

wallpaper released the highly toxic gas arsine from arsenic containing

pigments (Gravesen, et al., 1994).

>

> Fungi can also produce secondary metabolites as needed. These are not

produced at all times since they require extra energy from the organism.

Such secondary metabolites are the compounds that are frequently identified

with typically " moldy " or " musty " smells associated with the presence of

growing mold. However, compounds such as pinene and limonene that are used

as solvents and cleaning agents can also have a fungal source. Depending on

concentration, these compounds are considered to have a pleasant or " clean "

odor by some people. Fungal volatile secondary metabolites also impart

flavors and odors to food. Some of these, as in certain cheeses, are deemed

desirable, while others may be associated with food spoilage. There is

little information about the advantage that the production of volatile

secondary metabolites imparts to the fungal organism. The production of some

compounds is closely related to sporulation of the organism. " Off " tastes

may be of selective advantage to the survival of the fungus, if not to the

consumer.

>

> In addition to mucous membrane irritation, 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 (and to a

lesser extent the vagus nerve). This mixed (sensory and motor) nerve

responds to pungency, not odor, by initiating avoidance reactions, including

breath holding, discomfort, or paresthesias, or odd 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. Decreased attention, disorientation,

diminished reflex time, dizziness and other effects can also result from

such exposures (Otto et al., 1989)

>

> It is difficult to determine whether the level of volatile compounds

produced by fungi influence the total concentration of common VOCs found

indoors to any great extent. A mold-contaminated building may have a

significant contribution derived from its fungal contaminants that is added

to those VOCs emitted by building materials, paints, plastics and cleaners.

and co-workers (1988) measured a total VOC concentration approaching

the levels at which Otto et al., (1989) found trigeminal nerve effects.

>

> At higher exposure levels, VOCs from any source are mucous membrane

irritants, and can have an effect on the central nervous system, producing

such symptoms as headache, attention deficit, inability to concentrate or

dizziness.

>

> Adverse Reactions to Odor

> Odors produced by molds may also adversely affect some individuals.

Ability to perceive odors and respond to them is highly variable among

people. Some individuals can detect extremely low concentrations of volatile

compounds, while others require high levels for perception. An analogy to

music may give perspective to odor response. What is beautiful music to one

individual is unbearable noise to another. Some people derive enjoyment from

odors of all kinds. Others may respond with headache, nasal stuffiness,

nausea or even vomiting to certain odors including various perfumes,

cigarette smoke, diesel exhaust or moldy odors. It is not know whether such

responses are learned, or are time-dependent sensitization of portions of

the brain, perhaps mediated through the olfactory sense (Bell, et al.,

1993a; Bell et al., 1993b), or whether they serve a protective function.

Asthmatics may respond to odors with symptoms.

>

> (IAQ Tech Tip #47 will have the second part to this article.)

>

> Author

> Harriet M. Ammann is a senior toxicologist for Washington State Department

of Health, Office of Environmental Health Assessments. She provides support

to a variety of environmental health programs including ambient and indoor

air programs. She has participated in evaluations of schools and public

buildings with air quality problems, and has presented on toxic effects from

air contaminants, indoors and out, effect on sensitive populations, and

other health issues throughout the state. Through her work, she has

developed an interest in the toxicology of mold as an indoor air

contaminant, and has published and presented on mold toxicity relating to

human health.

>

> References for this article are located at:

> http://www.doh.wa.gov/ehp/oehas/mold.html

> __________________

> IAQ NEWS & EVENTS

> ^^^^^^^^^^^^^^^^^^

> Microbial Fact #1: Campylobacter jejuni is one of the leading causes of

bacterial diarrhea in the United States.

>

> Fungal Fact #1: The presence of fungi in the bloodstream is known as

Fungemia. The condition is becoming increasingly important due to the

number of individuals with weakened immune systems.

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