Farm Safety Association, Inc.
Farmer's
lung is an allergy caused by dust from moldy hay, straw and
grain. In early stages of the disease, it can seem like nothing
worse than a nagging winter cold. If ignored, the allergic
reaction can cause permanent lung damage. The victim may be
forced to give up farming and -- in some cases -- may suffer
from permanent disability or even death.
Early
diagnosis is crucial if lasting damage is to be prevented.
Because farmer's lung is characterized by cold or flu-like
symptoms, early detection is difficult. Many victims won't
even bother to visit a doctor despite persistent symptoms.
When they do, the exposure to moldy crop material is rarely
mentioned to the physician. This can be disastrous, because
each exposure increases the damage. Farmers who don't
seek medical help could saddle their families with an invalid.
When
crops are stored without sufficient drying, they begin to
heat. Many kinds of mold grow in such environments. When a
farmer works with such material -- for example, when a bale
of hay is broken open -- the mold is released as part of a
very fine dust. A farmer who is working indoors can inhale
a large amount of this dust in a very short time.
Because
the dust is so fine, it gets past defense systems in the nose
and throat. When the dust reaches the inner parts of the lungs
(called the alveoli), the lungs' internal defense system takes
over. In most cases, the dust is removed without damage. However,
an allergy to the material develops in a few individuals.
In other words, the body 'assumes' that the mold is more dangerous
than is really the case, and prepares to combat the intruders.
The first
exposure in sensitive individuals only creates the allergy.
Every subsequent exposure triggers an allergic reaction. The
body's immune system goes to work against the mold, producing
symptoms which may resemble anything from a cold to pneumonia.
Scar tissue (fibrosis) forms within the lungs. While cold-like
symptoms may clear up, the fibrosis is permanent.
Lung
damage may be too slight to notice in the early stages of
farmer's lung. However, each subsequent exposure increases
tissue damage. A victim will soon begin to notice that they
are short of breath. At first, this makes strenuous work more
difficult. Even routine tasks become too much after frequent,
repeated exposure. Eventually, the victim may find it a struggle
to even get out of a chair.
The allergic
reactions of farmer's lung are usually divided into either
acute or chronic attacks. Acute reactions are most noticeable
but, by being ignored, the chronic form can do more long-term
damage.
Acute
reactions occur when a farmer is especially sensitive and/or
when there is very heavy exposure to moldy dust. Symptoms
of an acute attack develop four to eight hours after exposure.
They resemble flu or even pneumonia -- in extreme cases, the
victim may go into shock and die!
Symptoms
of acute farmer's lung include:
- Fever
- Chills
- A
dripping nose
- An
irritating and harassing cough
- Blood-streaked
sputum
- Laboured
or difficult breathing, with a feeling of tightness in the
chest.
- Crackling
breathing
- Muscular
pain
- Depression
It is
easy to see why these symptoms could be mistaken for a case
of the flu. That's why milder attacks are often left to "run
their course", without a visit to a doctor. In the more extreme
cases, the need for hospital care becomes obvious.
Symptoms
of an acute farmer's lung attack usually decrease after 12
hours, but may linger for up to two weeks. Severe attacks
can last as long as 12 weeks.
Working
with dusty feed can produce another respiratory affliction,
called Toxic Organic Dust Syndrome (TODS). It, too, is caused
by exposure to very large amounts of dust. TODS symptoms are
identical to those resulting from an acute farmer's lung attack.
However, TODS is not and allergic reaction. While anyone
can get TODS (and can become very sick from this condition),
most people recover completely. Having TODS does not damage
your lungs, and does not increase the risk of getting ODS
again.
While
acute attacks are most noticeable, the chronic form of farmer's
lung is more common. Gradual development often leads victims
to dismiss the chronic form as something minor, like a nagging
chest cold. This makes chronic farmer's lung especially
dangerous. By the time an affected farmer goes to the
doctor and the disease is diagnosed, there can already be
serious damage.
Chronic
farmer's lung results from repeated exposure to moldy dust.
The quantities of dust may be so small that the farmer is
hardly aware of them.
Chronic
farmer's lung has several symptoms:
- Occasional
fever and sweating at night
- Progressively
increasing shortness of breath
- Chronic
cough
- Generalized
aches and pains
- Appetite
depression and weight loss
- Weakness,
loss of energy
- Depression
Because
the shortness of breath develops gradually, a victim may not
even be aware of the change. Also, the last three symptoms
-- weight loss, lack of energy and depression -- tend to push
the other symptoms into the background.
The risks
of becoming a victim of farmer's lung are fairly small. Studies
suggest that fewer than 10 percent of farmers -- perhaps less
than five percent -- are at risk of developing this condition.
However, there is no way of finding out in advance whether
or not you are immune.
Risks
increase when crops have been stored in damp or 'tough' conditions.
Working with such material outdoors poses minimal danger,
because the moldy dust is quickly dispersed. The greatest
danger occurs during the months when moldy crops are being
handled indoors. Dairy farmers are the most common victims.
While
farmer's lung is usually associated with the handling of hay,
any moldy plant material can be responsible. The list
includes grain, straw, silage, and even tobacco. Uncapping
a silo or cleaning out a grain bin usually releases large
quantities of moldy dust.
Victims
often try to ignore the symptoms of farmer's lung. They find
it easier to dismiss their condition as just a cold or flu
that "won't go away". This is dangerous -- any delay in prevention
and treatment will increase lung damage!
If you
experience any of the following, contact your doctor immediately:
- A
sudden illness that develops a few hours after you have
handled moldy crop materials
- A
chronic cough
- A
general feeling of tiredness or depression
To help
your doctor make an accurate diagnosis, emphasize that you
have been exposed to dust from moldy crops. A series of procedures
-- which might include a blood test, a chest x-ray, and a
breathing capacity test may be used to confirm or disprove
a tentative diagnosis.
Farmer's
lung can be controlled, but it can not be cured. In
acute cases, the symptoms can be treated with bed rest and
oxygen therapy. Medication can be used to control symptoms
in chronic cases. However, this can be dangerous, because
damage to the lungs may continue without the victim's awareness.
The only
proven treatment for chronic farmer's lung victims is the
avoidance of contact with moldy crop materials. Just as there
is no way of curing the allergy once it has developed, lung
damage can not be repaired.
In milder
cases that are detected early, avoiding contact with the molds
will prevent further lung damage. In severe cases, the victim
will have to quit farming.
There
is no way of knowing in advance whether or not you are immune
to the molds that cause farmer's lung. The only way to prevent
this condition is to avoid contact with dust from moldy plant
material. While it is difficult to completely eliminate contact,
there are several measures that will minimize exposure to
the moldy dust.
- Make
sure that crops are adequately dried prior to store. This
is the key to stopping mold growth. Artificial drying systems
and preservatives can play a role in preventing mold development.
- If
possible, wet hay should be ensiled.
- Always
use a plastic sheet to cap open silos -- don't use plant material.
Hold the edges of the sheet down with heavy weights, such
as tires.
- Wet
down the top of a silo before uncapping the ensiled material.
This prevents moldy dust from becoming airborne. This should
be done even if the silage was covered with a plastic sheet,
because the top layers still tend to mold.
- Use
the same wetting techniques when cleaning out grain bins or
other areas that are likely to be dusty.
- Provide
as much ventilation as possible when working in dusty areas.
For example, make sure doors and windows are open. If practical,
construct new openings to provide more ventilation.
- Move
the work outdoors whenever possible. While this is usually
not practical in the case of feeding operations, be sure to
open bales that you know are moldy outdoors.
- Avoid
dusty work in confined areas. When constructing new farm buildings
or modifying older structures, keep facilities as open as
possible.
- When
you have to work with moldy material, try to keep your distance.
If you have to break open a moldy bale, do so with a fork,
instead of bending over and using your hands.
- Mechanize
feeding operations if economically feasible. For example,
handling large round bales with a tractor keeps an operator
away from the moldy dust.
- In
some cases, it is best to wear a respirator. Make sure
that it is an approved toxic dust respirator. You must
familiarize yourself with correct procedures for using and
maintaining the respirator. A respirator should never
be used as an excuse for skipping other precautions!
Once
a person has farmer's lung, the only way to control it is
to avoid all contact with moldy dust. This means doubling
the precautions listed above. If possible, any dusty work
should be handled by someone other than the victim. Ignoring
these precautions will lead to progressively more serious
lung damage.
If necessary,
a farmer's lung victim should quit farming, rather than becoming
permanently disabled.
Most
farmers enjoy their occupation. When they take a chance with
farmer's lung, they are gambling on being forced out of a
way of life they love. Even worse, they risk being too weak
to do work of any kind!
The simple
precautions that minimize your chances of developing farmer's
lung are mostly common sense. Clearly, the risks of ignoring
these preventive measures are not worth taking.
Disclaimer
and Reproduction Information: Information in NASD does not represent
NIOSH policy. Information included in NASD appears by permission
of the author and/or copyright holder. More
NASD Review: 04/2002
The information and recommendations contained in this publication
are believed to be reliable and representative of contemporary
expert opinion on the subject material. The Farm Safety Association
does not guarantee absolute accuracy or sufficiency of subject
material, nor can it accept responsibility for health and safety
recommendations that may have been omitted due to particular
and exceptional conditions and circumstances.
COPYRIGHT© 1990
Fact
Sheet
NO.
F-014
MARCH 1990
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