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Diatomaceous earth: safe to use for chickens or a health hazard?

Using diatomaceous earth causes people in the chicken world great angst. Is it the best thing ever, or a liability that can harm your flock's health?

Diatomaceous Earth - pin for later.

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I'm not going to presume to tell you what to do.

As with many things in life, you must examine the facts and make a decision for yourself about what's best in your own situation. 

That decision will not be the same for everyone. It will depend on your circumstances and your point of view.

My aim here is simply to present the facts as I know them, with proper sources as my foundation, and to tell you what I do, and why.

The rest is up to you. 

Let's start with the basics...

What is diatomaceous earth (DE)?

In terms of knowing whether it's a safe, natural substance, it helps to know how diatomaceous earth is formed.

It's made from the fossils of microscopic aquatic algae called diatoms. Over many thousands of years, diatoms collected in rivers and streams. Their skeletons are made from silica, and it's that which is mined from those areas today.

The mined substance is then ground into a fine powder.

A computer rendering of a star diatom.A computer rendering of a diatom - they're too small to be seen with the naked eye.

The fossilised diatoms are made of almost pure amorphous silicon. This is important, because it's the crystalline form of silica which can cause silicosis - a form of lung cancer(1).

So it's important when buying it to make sure the crystalline component is as low as possible. In the US, a product is considered safe if it is less than 2% crystalline silica, but that's considered high in other countries.

How does it work?

Here's a simple scientific explanation for how diatomaceous earth works for external parasites like red mite and lice:

"Diatomaceous earth causes insects to dry out and die by absorbing the oils and fats from the cuticle of the insect's exoskeleton. Its sharp edges are abrasive, speeding up the process. It remains effective as long as it is kept dry and undisturbed"(2).


Where's best to buy diatomaceous earth and what should you look for?

Food grade diatomaceous earth is generally available from food and feed stores, or online. Wherever you buy from, for use with your chickens make sure it...

  • is food grade only
  • contains less than 2% crystalline silica (and if possible, lower than that)
  • has no fillers (some contain chalk or sand)
  • is mined as locally as possible
  • comes packed in a strong, airtight bag - the last thing you want when you open a package is the dust flying everywhere.

This brand contains less than 1% crystalline silica. (It doesn't say that anywhere on the product, so I wrote to the manufacturer who confirmed). It also has a free powder duster, which we'll see the benefit of later in this article.


Is diatomaceous earth safe? The risks.

  • As long as the amorphous content of DE is high and the crystalline content low, it is considered safe. The main concern has been about the risks of breathing in the dust.
  • One study demonstrated that mice forced to breathe diatomaceous earth for one hour each day for a year had an increased incidence of lung cancers(2). So it seems that prolonged, consistent exposure may cause harm.
  • As chicken keepers, we would not have that level of exposure, and if it's given correctly, neither would our chickens. But there's no doubt that DE is a very fine, dusty powder which, unless it's handled carefully, can fly everywhere.
A measuring spoon filled with diatomaceous earth.Diatomaceous earth is a fine powder - try not to breathe it in.
  • Gail Damerow, in "The Chicken Health Handbook", suggests that particles of diatomaceous earth can stick to chickens' lungs and create respiratory problems. However, it's known that it is crystalline silica, not amorphous, which causes respiratory issues.
  • Nevertheless, we need to make sure it's applied and used in such a way as to prevent chickens breathing it in - see below for tips as to how. 
  • For us as chicken keepers to be completely safe, I would suggest wearing a mask or some other form of nose and mouth covering when using it.
  • You don't need a surgical-type mask. Something like this does very well - or even a scarf tied tightly round your face.

What are the benefits for chickens? The evidence.

There are many claims made for diatomaceous earth related to humans. I'm not covering those in this article - I'm concerned solely with its uses for chickens.

1. Use of diatomaceous earth for controlling parasites externally.

There are numerous studies (see for example 23, 4) which have demonstrated that diatomaceous earth controls parasites like red mite, northern fowl mite, fleas and lice.

2. Uses of diatomaceous earth for controlling internal parasites.

The scientific evidence for controlling internal parasites, that is parasites like worms inside the chicken's body, is much less clear - in fact, I've been able to find no conclusive evidence that it's effective for this. 

It's also important to remember that unhatched worm larvae in the gut won't be affected by DE. For that reason I personally don't use it as a wormer.

3. Physical benefits of chickens eating diatomaceous earth.

Studies have shown that free range chickens who had DE added to their food were heavier and laid more and larger eggs containing more yolk and albumen(2)

So feeding diatomaceous earth to chickens in the right amount may be beneficial to their egg production.


Uses for diatomaceous earth with chickens.

Dust bathing.

Because it's known that diatomaceous earth can help control parasites, it can be added to dust baths for chickens. Dust baths help prevent parasites but they won't deal with an existing infestation quickly enough - for that you'll need to dust it onto the bird.

I'm lucky enough to have a large run, with several different areas the chickens use for their dust baths. They generally prefer to take their dustbath spas in loose earth, and I don't add any DE to those areas - the soil and grit they use is enough to keep parasites away.

I also provide an alternative of a child's sandpit turned into a dustbath in the shade of the fig tree in their run.

Some of my chickens enjoying a dust bath in a child's sandpit.Some of my flock enjoying a spa day in a dust bath made from a child's sandpit.

Because the earth is contained, I add diatomaceous earth to this dust bath. It's mainly filled with potting compost, which they love, and some ordinary loose soil from the garden. To that, I add diatomaceous earth to make up no more than one quarter of the total.

Mix the DE in well. Having it as only small part of a dust bath means there's not enough of it for the chickens to breathe it in.

Don't leave this out in the rain - we saw earlier that DE is effective only when it's dry. When it gets wet it turns into a sloppy mess.


Applying diatomaceous earth to food.

If you want to experiment with DE in your chickens' feed, the recommendation is to sprinkle it on and then mix it in at the rate of no more than 5% of the total(3). I find it hard to estimate in percentages, so I'd use a quarter cupful to every 5 cups of feed.


Dusting - how to apply diatomaceous earth to a chicken.

If your chicken has a particularly bad infestation of parasites like mites, a dust bath won't be enough. You'll first need to get rid of the mites which are already there.

Parasites tend to gather around the chicken's vent and at the shaft - the bottom of feathers where they meet the skin. Apply the diatomaceous earth there, and wherever else you see mites or lice crawling. Using an applicator like the one that comes with this brand is helpful.

Bear in mind that it's better for both you and your chickens not to breathe it in, so...

  • Don't dust chickens while you're in an enclosed area such as inside the coop - go outside.
  • Apply it on a day when there's no breeze, so you can control where it's applied without it flying off anywhere else.
  • I tend to cover the chicken's head with a towel, while holding her under my arm. It makes her feel safer and at the same time makes sure she's very unlikely to breathe in any dust.

Using diatomaceous earth in the chicken coop.

  • It's useful to dust areas where you know mites and lice are likely to collect, such as the underneath of roosting bars
Three Light Sussex hens on a wooden roosting bar.I check my roosts every week and dust the undersides with DE - that's where mites tend to gather.
  • Make sure you do it when your chickens are outside, and use a mask to cover your face. 
  • Some people use it in nesting boxes. I don't, unless I have a specific problem with an infestation and I'm waiting for the DE to work. It can take a couple of days to be effective on parasites, as it works by dehydrating them.

Conclusion: should you use diatomaceous earth?

As I said at the start, this is a personal decision we should all make for our own situation. Diatomaceous earth can cause sometimes quite heated discussions between chicken keepers, and we must all take the available information and make a balanced judgement.

Personally, I don't use a lot of it, but I do use it in my container dust bath, to dust chickens down if they have obvious signs of parasites, and to dust those parts of the coop where I know mites collect.

So, take the information here and make your decision. Whatever it is, it will be made based on proven studies and the best available information. 


If you found this article helpful, you may like these.

7 chicken coop design ideas - link.
Dealing with chicken mites - link.
All about nest boxes - link.
5 easy ways to prevent a rodent infestation - link.
Dustbaths for chickens - link.
Free newsletter. Link.

Sources.

A lot of "facts" on the internet are often people's individual views, often based on inaccurate information repeated from poor quality sources.

The information I provide in this article and others is based not just on my own experience, but on evidenced facts from scientific, peer-reviewed research and from highly respected and experienced poultry keepers such as Gail Dammerow.

Some of the sources I have used for this article are these. Direct links are given unless the article is on a "not secure" page.

1. Occupational Safety and Health Administration: Crystalline Silica Exposure - Health Hazard Information. Pub. 2002.

2. Bunch, T. R.; Bond, C.; Buhl, K.; Stone, D.: Diatomaceous Earth. Pub. National Pesticide Information Center, Oregon State University, 2013.

3. Bennet, D., et al: Effect of diatomaceous earth on parasite load, egg production and egg quality of free-range organic laying hens. Pub. Journal of Poultry Science, 2011.

4. Maurer, V. and Perler, E.:  Silicas for control of the poultry red mite. Paper published to the Joint Organic Congress, 2006. 


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