Respiratory Health with Dusty & Moldy Grain
By:
John Shutske, Damon Smith, Steve Kirkhorn, and Paul Esker
(Author
affiliations at end of article)
If you produce corn, soybeans, or other crops in the
Midwest, being exposed to dust while you are working is inevitable. Breathing grain dust
can affect the health and overall comfort for grain producers and others who
work in the grain industry. Exposures can occur:
- In the
combine
- While
unloading
- During
drying and processing
- In
bins
- While
grinding/mixing grain and other feed products (including hay and silage)
Grain dust is a complex soup made up of both organic and
inorganic particles. Some particles can be inhaled easily, and depending on
their size, dust can find its way deep into the respiratory system and cause a
range of negative health effects. Smaller particles are generally more harmful because they can find their way more deeply into the lungs. Grain
dust is biologically active, and is made up of:
- Plant
material
- Mold
and mold spores
- Insect
parts and excreta
- Bacteria
- Endotoxins
(toxins contained in the cell walls of some bacteria)
- Soil
Exposure to Small
Concentrations During Normal Work
Most people will have some reaction to dusty conditions
during harvest. Often, this will be a nuisance reaction (like a runny nose) or irritation, but
in some cases, bigger health problems are possible. Even in the cab of a
combine, there is some dust (1 to 15 mg of dust per cubic meter). Also endotoxins (even
with a sealed cab and proper air filtration) can reach limits that cause symptoms
for some individuals. At low dust levels that a healthy person might routinely encounter
during harvest operations, developing a cough is common. This might be an intermittent
cough, often producing more phlegm when actual work is happening around dust. Other
common symptoms are:
- Chest
tightness and/or wheezing
- Sore/irritated
throat
- Nasal
and eye irritation
- Feeling
of being stuffed-up and congested
Chronic or acute bronchitis is common for those who
handle grain as the main lung passages get inflamed. Grain dust can also be a
significant and limiting problem for those with asthma.
Exposure to Higher Concentrations of
Grain Dust
Higher concentrations of dust exposure like you might
encounter close to a combine in operation, in a bin, or while unloading or
processing grain are a concern especially in years where there are higher
levels of mold present or when you have lower quality grain that might be more
dusty and prone to damage.
Moldy, damaged, dusty grain can cause significant health issues
for people. For many individuals, a heavy dose of dust even for a short time
period can lead to symptoms that occur a few (2 to 6) hours after exposure and may
noticeable after they’ve gone home at night. These symptoms from a heavy dose
of grain dust exposure can include:
- Cough
- Chest
tightness
- Malaise-general
feeling of discomfort, illness, or feeling “ill-at-ease”
- Headache
- Muscle
aches
- Fever
Why People React This Way to a “Massive”
Exposure to Moldy Grain
Most people who have worked around grain will occasionally
find themselves in the midst of a space that is obviously very dusty. This
“massive” exposure to a cloud of dust for several minutes or hours is something
that should be avoided. Though, total avoidance might not always be possible or
practical. A massive exposure to moldy, dusty grain even for a short period of
time can result in two distinct medical conditions. These conditions are also
common when exposed to dusty or moldy hay and silage. The two common conditions
look VERY similar and have the same cluster of symptoms outlined above (cough,
chest tightness, etc.) but they are actually quite medically different. These
two conditions are “Farmer’s Lung” or Farmer’s Hypersensitivity Pneumonitis (FHP) and Organic Dust Toxic
Syndrome (ODTS).
“Farmer’s Lung” or Farmer’s Hypersensitivity
Pneumonitis (FHP) is relatively less common and generally
affects about 1 in 20 exposed individuals. Many times farmers tell their health
provider about their symptoms and the reaction sometimes gets mislabeled as FHP.
However, FHP is a delayed allergic reaction caused when highly
sensitive people breathe in grain dusts causing their bodies to produce
“antibodies” as a reaction to the dust. Since FHP is an allergic reaction and
involves the body’s immune system, repeated exposures and bouts with FHP often get
worse with each exposure. Some individuals may become physically unable to work
in dusty areas and can develop permanent lung damage through repeated exposures.
Farmer’s Hypersensitivity Pneumonitis is most often brought on or made
worse by dust that contains mold, mold spores, and bacteria that had developed under
warm/hot storage conditions. These heat-loving organisms are actually more
likely to grow in stored hay or sometimes in the top layers of stored silage as
compared to grain that was standing out in the field, though exposures that
lead to FHP can occur from grain including stored grain. If you’ve been
diagnosed with FHP before, and get sick in the future while working around
grain (or hay/silage), it is a good idea to see your family doctor.
“Organic Dust Toxic Syndrome” or ODTS, as the name
suggests, is a toxic reaction as compared to the allergic
reaction that causes FHP. The respiratory system can get inflamed from the
dust, molds, bacteria, and endotoxins in grain dust. With ODTS, people develop
a set of symptoms that look very similar to FHP even though the actual reaction
by the body that causes the symptoms is quite different. People who develop
ODTS will usually recover in a few days. Permanent lung damage from ODTS is not
likely to occur with a single exposure, but the person might feel fairly sick
(fever, fatigue, cough, chest tightness, etc.) for a few days after exposure. Again,
your family doctor or other health professional should be consulted if you
develop this type of reaction. It is possible that repeated occurrences of ODTS
can lead to FHP and other allergic reactions in some people, so prevention is
important.
A difficult problem is that since Farmer’s Lung (FHP)
and Organic Dust Toxic Syndrome (ODTS) have such similar
symptoms, it is hard even for health professionals to recognize and know the
difference. Additional medical testing will be needed to tell the two
apart. Medical treatment is also different. References cited at the end of this
article might be helpful for your physician if you visit your doctor’s office
with serious problems that you think might be connected to harvesting or
handling dusty and moldy grain.
Another concern in the late fall is that respiratory
symptoms that result from grain dust exposure can look much like seasonal influenza.
If you’ve been working in dusty conditions and end up with a “flu-like
illness,” make sure you let your healthcare provider know you’ve had
significant dust exposures. Influenza is a viral illness and is treated in a
different manner from either FHP or ODTS.
Controlling Exposure Risks
Grain dust exposure and the associated problems and health
symptoms are complex. Here are some specific things you can do to control your
risk:
- Have
the correct and clean air filter in place when operating a grain combine. Use
the appropriate setting on the blower in the cab whether you are using the
heater or the A/C. This will minimize dust concentrations in the cab by
creating slight pressure inside the operator’s station. When
replacing cab air filters, make sure gaskets are intact and installed
correctly and that the air is being well-filtered.
- Avoid
direct exposures to dust whenever possible, regardless of your
sensitivity. Stay in the cab with the door closed when unloading. If
you’re outside unloading or moving grain in other ways, use the wind to your
advantage rather that standing directly in a cloud of dust any time grain
is being moved.
- Properly
adjust your combine to minimize grain damage. This will help to
also minimize the amount of dust being generated. Properly harvested grain
will also store better and for longer periods of time with fewer mold and
insect issues.
- Wear
a NIOSH-approved and certified “N-95” dust mask (respirator) that fits your
face properly. This is
especially critical if you find yourself working in a very
dusty situation that cannot be avoided. CAUTION: Wear a respirator only if
you are free of health problems, particularly with your heart and lungs. Respirators
are only effective if you are cleanly shaven. Local health professionals
can be a great source of information and can recommend the type of
respirator that can be safely worn if a person has any underlying medical
conditions including cardiac and respiratory conditions. If you have a beard or need extra
protection, a powered air purifying respirator (PAPR) also commonly known
as an “air helmet” can be used in these situations. If you work in a
facility where worker safety regulations for respiratory protection apply
(such as a grain elevator or feed mill), there are other mandated regulatory
requirements before a dust mask or other type of respirator can be worn by
workers.
- Avoid
dust exposure if you have any chronic respiratory health issues,
including asthma, previous experience with Farmer’s Hypersensitivity
Pneumonitis, or existing respiratory infections or conditions. Individuals
who have these conditions should be alert for symptoms, even when working
in a relatively clean environment like the cab of a combine, and should
minimize their exposure to dust.
- If you
feel sick, call your health care provider. If you find yourself
working in a very dusty situation (like loading or cleaning out a bin or
getting a heavy, prolonged exposure near a combine in the field) and end
up feeling sick a few hours later, call for medical advice. Again,
your problem may be a condition like ODTS or FHP, but you may also have seasonal
influenza or another illness.
- Smoking
tends to make any type of symptoms or reaction caused by dust exposure
much worse. Realize that smoking increases the risk of developing
respiratory diseases such as emphysema and chronic bronchitis.
Authors:
Paul Esker, PhD, University of Costa Rica, San José, Science
Education, Mathematics Education, Plant Protection and Animal Health.
Steve Kirkhorn, MD, Former Medical Director, National
Farm Medicine Center – Marshfield Clinic
References:
- Kirkhorn SR. Agricultural Respiratory Health in Critical Need. Partners in Agricultural Health. Wisconsin Office of Rural Health. Available at: http://worh.org/files/AgHealth/resp.pdf
- Donham, K. J., & Thelin, A. (2006). Agricultural medicine: occupational and environmental health for the health professions. Wiley-Blackwell. (Chapter 3 contains information that can help a health professional differentiate between Farmer’s Hypersensitivity Pneumonitis and ODTS).
- Girard, M., Lacasse, Y., & Cormier, Y. (2009). Hypersensitivity pneumonitis. Allergy, 64(3), 322-334.
- Kirkhorn, S. R., & Garry, V. F. (2000). Agricultural lung diseases. Environmental health perspectives, 108(Suppl 4), 705.
- Seifert, S. A., Essen, S. V., Jacobitz, K., Crouch, R., & Lintner, C. P. (2003). Organic Dust Toxic Syndrome: A Review: REVIEW. Journal of Toxicology: Clinical Toxicology, 41(2), 185-193.
