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Mold Health Article
Respiratory Hazards: Molds and Fungi
Fact Sheet no. 7
Revised and Reprinted August 1999
Farmers are exposed to many respiratory irritants as they perform their
work and therefore are at risk for lung diseases. Damp grains, straw and
hay provide ideal growing conditions for molds and fungi in stored grain
and livestock feeds. Information on molds and fungi may be found under
such terms as mycotoxins, aflatoxins, ochratoxins, thermophilic
actinomycetes and estrogenic compounds. Some effects caused of exposure
to the mold or fungi and some effects are caused by endotoxins (poisons)
produced by these organisms.
Conditions for Growth
Many molds and fungi occur naturally in the soil. Fungal spores can be
carried attached to grain dust along with bacteria, insect parts and
wastes, rodent hair and wastes, and pollen. During harvest these
particles may be picked up and deposited in storage facilities along
with the grains. Grain stored with a moisture content of greater than
14% increases the likelihood of mold and fungi growth. Mold growth
occurs between 20-30°C but fungi can grow in temperatures as low as 5°C.
Large bales create conditions favourable for mold growth. Molds and
fungi typically produce a white, sharp smelling dust. Heavy
concentrations of mold spores have also been described as dry, white or
grey powder or clouds.
Activities
Closed environments, such as bins and barns, may have increased
concentrations of molds and fungi. Activities that take place in these
closed environments may increase the farmer's exposure to mold-laden
dusts potentially resulting in illness. Up to 75% of cases in studies
have developed some symptoms after extreme exposure to dust while
handling grain.
Examples of work tasks that have produced symptoms include:
- cleaning moldy grain out of bins
- cleaning out moldy grain to dry it
- exposure to moldy silage
- cleaning out harvest equipment (including grain
dryers) in preparation for the next year's harvest.
Routes of Entry
Most of the information that is available on health effects of molds and
fungi is related to breathing in these organisms carried along with
dust. The extremely small size of mold and fungal spores allows them to
enter deep into the lungs by bypassing the body's normal defences such
as the lining of those nose, coughing and sneezing. Molds and fungi can
be carried accidentally to the mouth from hands and other exposed skin
and be absorbed through the stomach and intestines.
Health Effects
Inhaling molds and fungi in dust can cause a variety of (immediate) and
(long term health problems. Immediate health effects include allergies,
skin irritation, poor appetite, headache, and vomiting. Long term health
effects can include emphysema, chronic bronchitis, lung fibrosis,
dermatitis (skin inflammation), and lung and intestinal cancers.
Medical Conditions
Exposure to molds/fungi in dust may cause a number of medical
conditions*. Following are brief descriptions of some conditions that
have been identified after exposure to these dusts.
Farm's Lung Disease (FLD)
- Symptoms may develop within 4-6 hours after
exposure to moldy hay or grain. Symptoms include weakness, chills,
cough, fever, and a general feeling of unwellness. This disease may
also have a more gradual onset with laboured breathing, weight loss
and increasing fatigue. Blood tests, x-rays, and lung tests will show
changes from normal. The lungs can be permanently damaged. This is an
allergic reaction and can be triggered by increasingly small amounts
of dusts. FLD may eventually cause death from lung fibrosis if
individual does not avoid exposure to dusts or does not wear
respiratory protection. Because this is an allergic reaction, within a
small group, one individual will usually become ill.
Organic Dust Toxic Syndrome (ODTS)
- This disease occurs when individuals are exposed
to moldy grains, hay or silage. Initial symptoms include burning in
the eyes and throat, headache and sometimes a cough. Four to twelve
hours later an exposed person may suffer with fever, chest discomfort,
weakness, muscle aching, shortness of breath, and a nonproductive
cough. There is usually no permanent lung damage. Large amounts of
dust exposure are usually necessary to trigger the syndrome. Small
groups of exposed individuals may become ill.
Silo Filler's Disease
- This is an immediate reaction with the
individual experiencing shortness of breath. It is an inflammatory
reaction in the lung caused by nitrogen gas from silos. It may result
in problems with oxygen being absorbed into the body. X-ray shows lung
changes.
Asthma
- Many people who have been diagnosed with asthma
are very sensitive to molds and fungi. Exposure to molds and fungi may
cause a worsening of symptoms. These individuals are advised to wear a
protective device such as an airstream helmet or avoid exposure.
Other
- Some illnesses related to molds and fungi appear
less commonly. Examples of this are mycosis and mycotoxicosis.
Mycosis
- It is an effect on the body caused by the fungi
itself. Some fungi can lodge in the airways or in a distant part of
the lung and grow until a "fungus ball" is formed.
Mycotosicosis
- It is a poisoning of the body caused by the
toxins/wastes produced by a fungi. Symptoms include chills; fever; dry
irritating cough; abnormal blood results and x-ray. This illness does
not recur.
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*It is important to note that these illnesses can only be
distinguished by medical examination and testing. |
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ORGANIC DUST TOXIC SYNDROME |
FARMER'S LUNG DISEASE |
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TIME TO ONSET OF ILLNESS |
4-12 hours lasting 24-72 hours |
4-6 hours lasting about 12-24 hours |
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SYMPTOMS |
Burning eyes,throat, headache or cough when exposed followed by:
High fever, chest disconfort, weakness, non-productive cough |
Weakness, chills, cough, fever, malaise, shortness of breath, mucle
aches or Gradual onsed of labored breathing, weight loss, increasing
fatigue |
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EFFECTS |
Not known to cause permanent damage |
Reaction worsens with each exposure; permanent damage to lungs;
death may result |
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TRIGGERS |
Large amounts of dust. In small groups more than one individual may
become ill |
Increasingly smaller amounts of dust. Allergic reaction; usually
within a small group only one person becomes ill |
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DIAGNOSIS |
White blood count is raised |
Blood tests, x-rays and lung testing show abnormal results |
Preventing Mold Growth and Human Contact
- Avoid crop rotations that favour fungal
infection
- Prevent initial infection in grain by:
- drying to <13.5% moisture content
- storing at low temperatures
- Work outside when possible if bales and grain
appear moldy
- Use ventilation (fans, exhaust blowers, filters)
if you must work in an enclosed area.
- Wet down moldy materials to reduce dust
- Use mechanized systems to distance yourself
while handling moldy materials
- Use caution when harvesting crops that have
overwintered in the field. They provide ideal conditions for mold
growth
- Wear personal protective equipment if you must
handle moldy grain or feeds.
- Use caution when using bale-grinders or feed
mixers
Safety Equipment and Measures
- A disposable dust mask with two straps and a
mouldable metal strip or a respirator with dust filter cartridges (NIOSH
approved)
- Wear coveralls over work clothes
- Remove coveralls outside and wash exposed skin
(hands, face, neck) well before meals to remove mold/fungi, preventing
accidental ingestion while eating.
- Change air filters frequently on harvesting
equipment
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Although every
care had been taken in providing this information, the authors
accept no responsibility or liability for any consequences arising
from the use of such information. Reference list available
upon request. ©Centre for Agricultural Medicine, University
of Saskatchewan, 1999.
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