Compexity of The Indoor Environment from Water Intrusion

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An Abstract of:

The Complexity of Damp Indoor Environments and Human Health1

Jack D. Thrasher, Ph.D., Kaye H. Kilburn, M.D., Crawley,

M.ED., LADC

Water intrusion into homes and buildings leads to the growth

of microorganisms. The microorganisms consist of filamentous fungi

(molds) and bacteria. The result is a complex indoor environment

that has not received adequate scientific/medical research. We as

Environmental scientists and physicians need to speak out on this

issue. We will briefly review the complexity of this environment

along with known health problems consistent with exposure to multiple

toxins.

Fungi and bacteria and their by-products cause human

illness. These include infections; fungal and bacterial sinusitis;

respiratory diseases, skin disease, immunotoxic and neurotoxic

effects. Let us now look briefly at each of the components and their

known health effects.

Molds: Molds begin growing by 48 hours following water

intrusion. It is estimated that 50 % of the mold growth is hidden,

e.g. wall cavities. The signal molds are S. chartarum; Aspergillus

(11 species); Penicillium (10 species); Fusarium; Chaetomium,

Epicoccum, and Memnoniella. Certain species of these genera are in

higher concentrations in the indoor environment as compared to the

outdoors.

Bacteria: Both gram negative and gram positive bacteria are

present. The predominant gram negative organisms are several species

of the Actinomycetes (several species of Streptomyces) as well as

other genera, Mycobacteria and Nocardia spp. Human pathogens occur

in these groups and in addition Streptomyces and Nocardia isolated

from indoor environments are known to produce toxins that can affect

human health. The gram negative bacteria include a variety of genera

that do release endotoxins into the air and dust of an infested

facility. Finally, the toxins produced by S. californicus were shown

to act synergistically with trichothecenes in vitro

Particulates: Colonies of molds and bacteria shed

particulates ranging from <0.2 to 9 microns. The particulates can be

divided into two general fractions: large and fine. The large

particulates consist of spores and hyphae fragments usually collected

2 micron filters. These contain mycotoxins, various secreted enzymes

as well as siderophores and hemolysins. The fine particulate matter

is less than 2 microns and ranges to nanoparticle size. This

fraction is shed at vibrations at 1-20 hertz that are set up by

normal human activity (walking, talking, TV etc.). These

particulates differ from the larger fraction in that they are up to

320 times more numerous than large particulates and are inhaled deep

into alveolar spaces with simple diffusion into the blood. The fine

particulates also contain the mycotoxins and other mold/bacterial by-

products. In addition, the spores of Streptomyces californicus and

other actinobacter are in this fraction.

Mycotoxins: Mycotoxins are present in the indoor

environment. The trichothecenes are present in the large and fine

particulate matter. Sterigmatocystin, chaetoglobosins, trichodrmin,

trichodermol, spirocyclic drimanes, ochratoxin A, penicillic acid,

verrucosidins, griseofulvin, roquefortine C and others have been

demonstrated in bulk and dust samples of homes and office buildings.

A recent paper reported trichothecenes and sterigmatocystin in 45 of

62 building material samples. If present, tremorgens are capable of

interfering with synaptic transmissions involving glutamate,

aspartate, GABA, serotonin) and block complex sphingolipids via

inhibition of ceramide synthetase.

Volatile Organic Compounds (VOCS): Molds and bacteria release VOCS

that include alcohols, aldehydes, organo-sulfides, ammonia and

amines. These add to other sources from indoor furnishings, cleaning

agents and from outdoor sources. The human health effects have

received very little attention..

Extra Cellular Proteins: Molds secrete enzymes that allow the

organism to digest the substrate upon which they grow. These

include lipases, proteinases, metalloproteinases, fibrinolytic

enzymes, galactosidases, siderophores, and hemolysins among others.

This occurs on building materials as well as in the infectious

state. These proteins can act as antigens and/or inflammatory agents

producing lung disease and the release of proinflammatory cytokines.

Hemolysins have been implicated in pulmonary hemosiderosis with

reference to S. chartarum. However, eleven species of Aspergillus

and 10 species of Penicillium found in contaminated homes in

Cleveland, Ohio also produce hemolysins. Thus, it is critical to

identify all species within a contaminated structure in order to

identify potential causes of upper and lower respiratory bleeding in

both children and adults.

Extra Cellular Polysaccacharides (EPS): The cell wall of is a

complex structure consisting of polypeptide polysaccharides (EPS),

lipids and proteins. Some of the cell wall components are directly

associated with tissue colonization and damage, e.g. aspergillosis.

Two EPS compounds released into the environment in vivo and in vitro

are the 1, 3-beta-D-glucans and galactomannans. Both are considered

biomarkers of exposure to and infection by molds, e.g. Aspergillus

and Candida spp. The glucans are present in the indoor air and dust

and promote airway inflammation as shown by bronchoalveolar lavage in

exposed humans and animals.

Endotoxins: Endotoxins released by gram negative bacteria have also

been identified in the indoor air and dust of contaminated homes.

They can cause: fever; leukopenia, hypoglycemia; hypotension;

decreased organ perfusion (brain, ears, kidneys, etc.); activation of

C3 complement; bleeding; intravascular coagulation, death and late

inflammatory responses (endotoxemia). They act by binding to TLR4

(Toll-like receptors), inhibiting IgE mechanisms and initiating

proinflammatory responses. In animals models of neurological disease

endotoxins are known to cause the expression of proinflammatory

markers of microglia as well as injury to oligodenrocytes.

Conclusions: It is obvious that the indoor environment resulting

from water intrusion is complex with several different interactions

occurring simultaneously. Although attempts have been made to

determine the health effects of exposure to molds and bacteria,

additional work is sorely needed.

1This article can be obtained in its entirety with over 100

references by contacting Dr. Thrasher. E- mail -

toxicologist1@...

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