DIATOMACEOUS EARTH (DE) THE CUT AND DRY TRUTH
Food grade diatomaceous earth (also known as DE and fossilized shell flour) is a naturally-occurring, fossilized mineral dust with microscopic, razor-sharp edges that act as a mechanical insecticide by slicing into insects’ bodies and absorbing their bodily fluids thereby dehydrating them to death. I do not use or advocate the use of food grade diatomaceous earth with backyard chickens for any reason. The assurance that DE is a “natural” product lulls users into a false sense of safety about its regular use in chickens’ environment, but arsenic and mercury are natural too- natural does not mean safe for every purpose. The presence of DE in the environment is a health hazard to humans and chickens.
Silicon dioxide, the drying element in DE, exists primarily in the amorphous form, but also contains the more dangerous, crystalline form. The Material Data Safety Sheets written by manufacturers of food grade DE caution users to avoid creating dust, avoid inhaling dust, use local exhaust ventilation, wear coveralls, use respirators and wear safety goggles. The use of DE in the coop or dust bath ensures its constant presence in the air.
DE is a respiratory hazard to chickens- it is known to create scar tissue on the lungs that impairs respiration. While chickens may live a decade or less, breathing crystalline silica regularly is known to cause cancer and chronic pulmonary disease in humans, so even if chicken DE weren’t a health hazard to chickens, the daily danger of airborne, respirable DE particles in the extremely dusty atmosphere of a chicken yard every day ought to scare the tar out of users. Yes, it’s natural, yes it’s organic, yes it’s cancer-causing when inhaled in sufficient amounts over time.
IMMUNE SYSTEM SUPPRESSANT
While we typically think of the immune system as working inside the body, skin is the largest organ of the chicken’s immune system and its first line of defense against pathogens and disease. Skin’s functions are to act as a barrier against pathogens and other potentially harmful substances, retain vital fluids and gases, and alerts chickens to the proximity of potential threats with its network of highly sensitive nerve endings. Another aspect of the immune system is the mucous membranes in the mouth, vent, eyes and ears that possess populations of beneficial microflora charged with defending ports of access into the chicken’s body from invasion by pathogens. DE dries these moist membranes, disrupting the beneficial populations of microflora, rendering the bird vulnerable to pathogens and disease. Yet another detrimental drying effect of DE on the immune system is robbing chickens of the natural oils they preen onto their feathers to maintain good condition and provide effective insulation in cold weather.
WHY DO SOME CHICKEN KEEPERS USE DE?
I think many backyard chicken keepers believe they should use DE because someone recommended it to them without understanding its dangers. A look at commonly articulated reasons for using DE with chickens reveals several things: it’s unnecessary, it’s unsafe, and it’s ineffective for the purported uses.
The primary purported benefits of food grade DE by chicken hobbyists are as a drying agent in coop litter, an insecticide and a de-wormer, but food grade DE is not approved in the US for any of those uses with chickens. DE is only approved for use as a pelleting aid, anti-caking agent and flow agent in livestock feed not to exceed 2% of the total diet. In other words, it helps pellets stick together and prevents wet feed ingredients from sticking to storage containers and machinery.1
Purported Use #1: Absorb Moisture & Neutralize Ammonia
While densely populated commercial poultry houses are expected to have difficulty controlling moisture and ammonia fumes in the litter, backyard chicken keepers should not. There is no excuse for a backyard chicken coop to be so wet or so dirty that it smells like ammonia. If your chicken coop smells like ammonia, the coop should be cleaned, ventilation improved, and an alternate litter type used that will keep the coop dry. DE does not neutralize ammonia.
Purported Use #2: Insecticide
We would never fathom taking antibiotics daily as a preventative due to fear of one day contracting a bacterial infection; similarly, chickens should not be subjected to any insecticide daily as a preventative measure due to the fear of lice or mites. It is unnatural and unnecessary to seek to eradicate every insect in the chicken yard, all day, every day with diatomaceous earth.
If it ever becomes necessary to use an insecticide, there are other much more effective, natural insecticides available that do not endanger health of chickens, humans or beneficial insects as diatomaceous earth does.
Purported Use #3: De-wormer
Because DE is an absorbent, when placed in a wet environment such as the digestive tract, it becomes ineffective. DE particles cannot dehydrate and kill worms or intestinal parasites in the gut if the particles are already full of water in the same way a sponge saturated with water cannot absorb more water. Further, the sharp edges have the capacity to inflict microscopic lacerations in the bird’s mouth, esophagus and crop- at least until they become fully saturated by bodily fluids.
Sources & further reading: See below.
Guide to Raising Chickens, Damerow, Gail. Storey Publishing, 1995.
& Internal Parasites of Poultry, Eva Wallner-Pendleton, DVM, MS,
Quarles, W. 1992. Diatomaceous earth for pest
control. The IPM practitioner. Monitoring Field Pest
Manage. 14:1–11. Quisenberry, J. H. 1967.
feed containing about 1% diatomaceous earth. US Pat. No. 3,271,161.
insecticides. J. Stored Prod. Res. 34:87–97. Kouba, M. 2003.