Respiratory Illness Caused by Mold and Dust: Farmer's Lung

by CDC

Who Needs to Know About Respiratory Illnesses?

• those working in dusty fields or buildings
• those handling moldy hay
• those working in silos
• those feeding or working with feedstuffs
• those working in corn silage
• those uncapping silos
• those cleaning grain bins
• those exposed to bird droppings or feather, hair, or fur dust
• those exposed to fish meal

Farmers account for more than 30% of adults disabled by respiratory illness, yet a large percentage of farmers are nonsmokers. If you work in any one of these situations, then you need to be aware of Farmer's Lung as well as other respiratory hazards.

Farmer's Lung is only one of the respiratory hazards for farmers, but it is a serious one. The number of farmers affected has also been increasing in recent years. This results from a growing awareness among farmers and that they have been seeing their physicians more frequently. The larger size of silos accounts for much of the increase.

What is Farmer's Lung?

Farmer's Lung is a noninfectious allergic disease caused by inhaling dust from moldy hay, straw or grain. It is a disease because the body reacts to the invading contaminants (mold spores) which the body's immune system cannot counteract.

The lungs allow oxygen to enter the bloodstream and carbon dioxide to exit the bloodstream. They are the location for a vital process for good health; but they are also the quickest and most direct route for hazardous contaminants to enter the body and the bloodstream. The results from exposure to mold spores can be so debilitating that some farmers are even forced to leave the occupation completely.

What are These Mold Spores and Why are They so Dangerous?

Mold spores are tiny bacteria less than 4 microns in size - so small that as many as 250,000 spores can fit on a pin head and a farmer can inhale as many as 750,000 of these spores per minute! They are produced by microorganisms which grow in moist hay and stored grain silage where the moisture content is high (30%) and the area is poorly ventilated.

When farmers move or work with hay and silage materials in which mold spores have grown, the mold spores attach themselves to airborne dust particles. The farmer not only inhales dust particles which may not be extremely hazardous, but he also inhales mold spores which are a serious hazard. Heavy concentrations of mold spores appear as dry, white or grey powder or clouds.

The body has natural defense filtering systems (such as mucous lining, coughing and sneezing) against dusty air which helps remove some contaminants, BUT most contaminants overpower and pass through these defenses. Mold spores not only bypass defenses because of their number, but also because they are so small.

Very fine particles, like mold spores, move into, accumulate and settle into the lower lungs. There they produce toxins. Remember that the lungs transfer oxygen to the bloodstream, and most of the actual exchange of carbon dioxide and oxygen takes place in the lower lungs. Now the lungs become a roadway for toxic materials to travel through the bloodstream with the oxygen. The body's reaction to the toxins permanently affects the lungs' ability to transfer oxygen into the bloodstream. The lung tissue becomes permanently scared and each exposure to mold spores increases the damage.

The body's last defense against these tiny invaders is to develop an allergy producing cold or pneumonia-like symptoms.

Symptoms of Lung Disease and State of Illness

The farmer will develop specific symptoms based upon the intensity of dust and spores to which he has been exposed or the intensity of his body's reaction to the dust and spores. He is also likely to develop an increased sensitivity to mold exposure, having more severe reactions with fewer exposures. In all cases, each exposure aggravates the problem.

Acute State

This is the most noticeable condition which typically begins 4 - 8 hours after exposure. Most farmers ignore the symptoms because they are so similar to a common summer cold.

Typical Symptoms:

• fatigue
• chills
• shortness of breath
• tightness in the chest

Subacute State

This is a more serious condition because symptoms will be stronger and remain longer even with no further exposure to moldy dust particles.

Typical Symptoms:

• severe shortness of breath with any exertion
• headache
• irritating cough

Chronic State This is the most serious condition because of its gradual onset and its long-lasting debilitation. At the chronic state, the disease becomes irreversible.

Typical Symptoms:

• chronic coughing
• progressively increasing and severe shortness of breath with even the slightest exertion
• physical weakness
• occasional fever and sweating at night
• appetite depression
• general aches and pains

Typically farmers develop chronic Farmer's Lung slowly over time after repeated exposure to mold spores because they continue to ignore the symptoms of acute attacks. However, it is possible to develop Chronic Farmer's Lung even after one acute attack.

A delay in seeking medical help damages the farmer most. Often, by the time a farmer sees a physician, there is already serious, permanent damage. And in some cases scar tissue (pulmonary fibrosis) develops, further interfering with the normal functions of the lungs.

About the Author

www.cdc.gov
The Centers for Disease Control and Prevention (CDC) is one of the 13 major operating components of the Department of Health and Human Services (HHS), which is the principal agency in the United States government for protecting the health and safety of all Americans and for providing essential human services, especially for those people who are least able to help themselves.