FROM SEWAGE SLUDGE DISPOSAL
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P.O. Box 2448, 1500 East Main Street, Room 124
Richmond, Virginia 23218 (804)786-1763


Bioaerosols include microbial cells (microorganisms), their reproductive units, and associated
metabolites that are volatile or small enough to sufficiently achieve aerial dispersion.
Categories of bioaerosols include viruses, bacteria, fungi, algae, and protozoa and
their products
(Burge, 1990a).

These microorganisms and their byproducts are naturally occurring and are considered to be
ubiquitous. Under certain environmental conditions, many bioaerosols can cause varying
symptoms, disorders, and diseases in humans, and they can survive for extended periods.
Microorganisms are a normal and essential component of the earth’s terrestrial and aquatic
ecosystems. Bacteria and fungi break down the complex molecules found in dead organic
materials from animals and plants, and recycle minerals and carbon to simple substances such
as carbon dioxide and nitrates. Microorganisms such as saprophytic bacteria and fungi, which
derive nutrients from non-living materials in the environment, are commonly found in the soil and
the atmosphere (Morey and Feeley, 1990).

Many of the medical symptoms of bioaerosol exposure are accentuated in indoor environments
due to the accumulation of the specific bioaerosol(s) as the result of poor building ventilation.
Microbial contamination in buildings can usually be tracked back to either unsanitary mechanical
equipment (e.g., growth in condensate pans, dirty filters and/or ductwork) or excess moisture (e.
g. flooding, leaks, condensation,damp filters, or elevated humidity) (Burge, 1987; Morey et al.,

Excessive mold and/or bacterial concentrations in indoor air primarily impact the health of
allergy-prone (atopic) individuals. Such persons may experience the relatively common
symptoms of allergic rhinitis or asthma shortly after initial exposure (Canadian Public Health
Association, 1987). Much less frequently, airborne microorganisms cause susceptible
individuals to develop severe hypersensitivity illnesses or opportunistic infections (Burge, 1987;
Moret et al., 1984). Two opportunistic fungal pathogens (e.g., Aspergillus niger and A.
fumigatus) can cause infection in persons with weakened immune systems (Raperand Fennell,
1965; Morey and Feeley. 1990).

Microorganisms may produce antigens (proteins or carbohydrates capable of stimulating an
immune response) in indoor water reservoirs which can aerosol (≤ 1.0 µm). Antigens of
appropriately small size apparently do not reach concentrations in free outdoor air that are
sufficient to cause sensitization (Burge, 1990a).

Allergic asthma and allergic rhinitis are two diseases which are apparently less dependent on
small aerosol size than hypersensitivity pneumonitis and humidifier fever, and are triggered by
continuing exposure to ambient levels of appropriate allergens (substances that induce
allergies), whether these allergens are indoors or outdoors (Salvaggio and Aukrust, 1981). It is
possible that diverse indoor factors, such as excessive humidity, unsuspected noxious particles,
and volatile irritants released from household goods or appliances, may exacerbate asthma in
the absence of sensitizing agents (Ahmed et al., 1982).


Some examples of viral bioaerosols which infect humans and are spread by aerosols, rather
than by direct contact only, are influenza(influenza A and B), measles (rubella), mumps, and
chicken pox (Knudsen, 1980; Nada et al., 1986).


Bacterial bioaerosols are responsible for such things as tuberculosis (Mycobacterium),
Legionnaires’ disease (Legionella pneumophila),and hypersensitivity pneumonitis
(Thermoactinomyces). Airborne transmission occurs when an infected person is coughing,
sneezing, actively shedding fresh organisms into air close to susceptible individuals, or even
talking or singing (Burge, 1990b)

Approximately 200 surveys made in various parts of the world of outdoor airborne spores
indicated that Cladosporium, Alternaria, Penicillium, and Aspergillus were the genera of fungi
which accounted for the highest mean percentages. Approximately 85% of patients found to be
allergic to molds will react to one or more of these same genera in circulating air (Binnie, 1989).
Alternaria sp., Cladosporium sp., andPenicillium sp., are three fungi which have been
associated with causing asthma and rhinitis. Penicillium species with spores of 2 to 3 microns
(µm) have apparently been responsible for several hypersensitivity pneumonitis epidemics
(Kreiss and Hodgson, 1984).
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The “moldy” or “mildew” odors in some indoor environments are associated with low levels of
volatile organic compounds (VOCs) in the air produced by fungi (Kaminski et al., 1974;
Canadian Department of Health & Welfare, 1987). Health effects have not been directly
attributable to these VOCs to date, but the VOCs and/or the organisms which produce them
may be contributory factors to complaints of headache, eye and throat irritation, nausea,
dizziness, and fatigue in subjects occupying contaminated interiors (Burge, 1990a).

Protozoa (i.e. amoebae, ciliates, etc.) can grow in indoor water reservoirs. A few of these
protozoa can cause severe infections (Manniset al., 1986), but most produce either antigenic or
toxic metabolic products which aerosol and may contribute to syndromes such as
hypersensitivity pneumonitis and humidifier fever (Edwards et al., 1976).

There are no practical identification methods for a number of fungal spores, algae,
actinomycetes, bacteria, as well as certain types of biogenic debris (Nagda et al., 1986).
National standards for levels or airborne microbes in buildings are not yet available (Kay et al.,


Ahmed, T., Marchette, B., Danta, L. et al. 1982. Effect of (0.1ppm) NO2 on Bronchial Reactivity
in Normals and Subjects with Bronchial Asthma. Am. Rev. Respir. Dis., 125: 152.

Binnie, P.W.H. 1987. Airborne Microbial Flora in Florida Homes. Proc. 4th International
Conference on Indoor Air Quality, Berlin, West Germany.

Burge, H.A. 1987. Approaches to the Control of Indoor Microbial Contamination. Proceedings of
IAQ '87: Practical Control of Indoor Air Problems. Atlanta: ASHRAE, Inc.

Burge, H.A. 1990a. Bioaerosols: Prevalence and Health Effects in the Indoor Environment. J.
Allergy and Clinical Immunology, Vol. 86(5):687-701

Burge, H.A. 1990b. Risks Associated with Indoor Infectious Aerosols. Toxicol. Ind. Health 6(2):
263-274.Canadian Dept. of Health & Welfare, Working Group on Fungi and Indoor Air. 1987.
Significance of Fungi in Indoor Air. Can. J. Public Health, 78:S1-13.

Col, G.T. and Samson, R.A. 1984. In: Al-Doory, Y. and Domson, J.F., eds. Mold Allergy.
Philadelphia, PA:

Lea and Febiges.Edwards, J.H., Griffiths, A.J., and Mullins, J. 1976. Protozoa as Sources of
Antigen in Humidifer Fever. Nature, 264: 438.

Kaminske, E., Stawicki, S., and Wasowicz, E. 1974. Volatile Flavor Compounds Produced by
Molds of Aspergillus, Penicillium, and FungiImperfecti. Appl. Microbiol., 27(6): 1001.

Kay, J.G., Keller, G.E., and Miller, J.F. 1991. Indoor Air Pollution: Radon, Bioaerosols, & VOC’s.
Chelsea, Michigan: Lewis Publishers.pp.259.

Kreiss, K. and Hodgson, M.J. 1984. Building-associated Epidemics. In:

Walsh, P.J., Dudney, C.S., and Copenhaver, E.D., eds. Indoor AirQuality. Boca Raton, Fla: CRC
Press.Kundsin, R.C. 1980. Airborne Contagion. Ann. NY Acad. Sci., 353:1.

Mannis, M.J., Tamaru, R., Roth A.M., Burns, M. and Thirkill, C. 1986. Acanthamoeba
Sclerokeratitis. Arch. Ophthalmol., 104: 1313.

Morey, P.R., Hodgson, M.L., et al. 1984. Environmental Studies in Moldy Office Buildings:
Biological Agents, Sources and Preventative Measures. Ann. Am. Conf. Gov. Ind. Hyg. 10:21-34.

Morey, PR., Clere, J.L., et al. 1986. Studies on Sources of Airborne Microorganisms and on
Indoor Air Quality in a Large Office Building.
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Proceedings of the IAQ '86: Managing Indoor Air for Health and Energy Conservation. Atlanta:

Morey, PR. and Feeley, Sr., J.C. 1990. The Landlord, Tenant, and Investigator: Their Needs,
Concerns, and Viewpoints. In:

Morey, PR., Feeley, Sr., J.C., and Otten, J.A., eds. Biological Contaminants in Indoor
Environments. Philadelphia, PA: ASTM.

Nagda, N.L., Rector, H.E., and Koontz, M.D. 1986. Guidelines for Monitoring Indoor Air Quality.
Hemisphere Publishing Corporation,Washington, D.C., pp. 270.

Raper, K.B. and Fennell, D.I. 1965. The Genus Aspergillus. Baltimore:

Williams & Wilkins.Salvaggio, J. and Aukrust, L. 1981. Mold-induced Astham. J. Allergy Clin.
Immunol., 68: 327.
ANTIGENS AND ALLERGENS are a major concern for women and the elderly living near sludge
disposal sites and for people who are exposed by using sludge on their lawn and garden.
Contaminated dust may collect in their homes causing Organic Toxic Dust syndrome, .
Organic toxic dust syndrome caused by dried sewage sludge dust may result in
pulmonary fribosis and other respiratory diseases.
Canada calls it "extrinsic allergic alveolitis".= Sewage Sludge Disease
Australia also calls it extrinsic allergic alveolitis" which may be.caused by sewage sludge
contaminated with micro-organisms.