Respiratory Disease: Dusts

Dusts can be either organic or inorganic, though most of the health issues are 
related to organic dusts.

o  Inorganic - Mineral dusts produced by tilling, harvesting, burning fields, harvesting 
    grapes and other fruit.  The primary component is silica from diatomaceous earth and 
    granite.  The health effects may include interstitial fibrosis or scarring. 
o  Organic - these dusts are made up of biologically active ingredients from plant and 
    animal material found in barns, silos, animal confinement operations, and grain 
    storage buildings and elevators. They include microorganisms and their inflammatory 
    by-products. These dusts are the primary cause of agricultural respiratory disease.



Grain dusts are an organic soup consisting of molds, bacteria endotoxins, bird and insect 
feces, pollens, mites, and pesticides.  The dusts can cause either respiratory irritation or 
allergic sensitization. Chronic low concentration exposures can eventually lead to sinus 
symptoms and chronic bronchitis.  There are a number of activities that are associated 
with the periodic release of high levels of dust with millions of mold and bacteria spores 
leading to acute respiratory symptoms including: 

     o  Silo unloading	
     o  Emptying grain bins
     o  Cleaning out old chicken coops
     o  Moving moldy grain and bedding
     o  Chopping straw or hay bales for bedding/feed
     o  Power washing inside of animal confinement buildings
     o  Loading/caging chickens and turkeys

	

The respiratory symptoms are caused by inflammation, from both endotoxins and the grain 
itself, which affects the immune system.  Farmer’s Hypersensitivity Pneumonitis results 
from sensitization to bacteria that grow in moldy straw, bedding, silage, and feed but is 
actually much less common than Organic Dust Toxic Syndrome (ODTS).  The 
clinical symptoms of the two conditions are identical and can only be determined by a 
combination of an accurate history and medical testing with pulmonary function testing, 
chest x-rays, and blood gases.  This is important because FHP is treated with steroids 
and ODTS resolves without treatment.  Over time with repeated exposures and 
symptoms, around 5% of those with ODTS, can become sensitized and develop FHP.

High levels of dust under the right conditions can also be explosive.  A recent example was 
a grain elevator explosion that occurred in southern Minnesota resulting in severe 
burns and a critically injured employee.