[Arid_gardener] Diatomaceous Earth - Fresh Water VS Salt Water

Fri Aug 4 00:16:51 MST 2006

Thank you, Susanne. I used to deal with a large gypsum mine and mill North of Globe at a time when their workmen began to have lung problems. The experience  left me a little paranoid about any dust regardless of its origin. After this DE debate opened up, I briefly searched the web without finding anything confirming the hazards in either fresh or salt water deposits if such a differential even exists. I have more to learn. That's not to say it isn't out there, just that I didn't find it in a brief search.

I spent 33 years with Unocal marketing a full range of products related to petroleum. Any remotely percieved materials-hazard had to be highlighted in flashing lights and we were required by law to supply upon demand an MSDS (Material Data Safety Sheet) with every one of the several hundred products we supplied. To avoid problems, we usually handed over a complete file to a safety engineer if they had one or the buyer/owner. We should find out if MSDS sheet exist for this material and distribute them to users or increase the awareness of the risk. 

So, you may be absolutely correct, Susanne but, with a compound so widely used in the home setting, one would expext the suppliers to print out hazards in great big neon letters to avoid liability and so that the dummest among us could concieve the risk. Diatoms are microscopic, distinguishable only under a microscope. Diatomaceous earth is the skeletal remains that have accummulated in layers from inches to hundreds of feet in shallow sea beds for millions of years. The hard rock deposits with which I am faliliar had to be mined and milled to a uniform size creating a lot of dust in huge dust collectors in the process. How they disposed of the dust was a question I never asked. I was once cited by a safety engineer for working without a mask in a posted area. The mask was in my pocket. Two such citations could have barred me from the quarry.

All things considered, it would be prudent, perhaps, for all of us to err on the side of safety to demand fresh water DE for insect control from our suppliers until we have some reliable authority that can clear the air one way or the other, but, I ain't that authority.

Dick Gross, MGV MCCE

----- Original Message ----- 
  From: Suzanne Vilardi 
  To: 'Dick Gross' 
  Sent: Thursday, August 03, 2006 6:17 PM
  Subject: RE: [Arid_gardener] Diatomaceous Earth - Fresh Water VS Salt Water

  Hi Dick, thank you for your eloquent and very informative response.  I really enjoy reading your contributions!  I didn't want to clutter the board with this bit of info, but I did notice you debating the merits or lack of, of the origins of DE (fresh H2O vs. salt), and I just wanted to say that I am pretty sure the differing factor is the SIZE of the skeletal remains.  The larger (salt) is more hazardous to inhale for children and pets.  There may be some other differences, but as I implied in my earlier posts, I am a collector of partial facts and veneer thing knowledge.  Just trying to learn myself...but one of the key reasons I have heard for not using pool grade DE is the breathing hazard factor, especially for pets.  

  Regards, Suzanne Vilardi

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  From: Dick Gross [mailto:rkgross3 at cox.net] 
  Sent: Tuesday, August 01, 2006 10:42 AM
  To: Suzanne Vilardi; arid_gardener at CALS.arizona.edu
  Subject: Re: [Arid_gardener] Diatomaceous Earth - Fresh Water VS Salt Water

  To contribute to the confusion, I believe diatomaceous earth is comprised of the skeletons of microscopic organisms (diatoms) deposited for millions of years in ancient sea beds. .

  The sharp skeletal structure scratches the undersides of crawling insects allowing body fluids to leak out. Cockaroaches aren't exactly crawling creatures. The effective control of the critter from my own yard using DE may be a figment of my imagination. They might have been eaten be geckos or field mice. Eroneous conclusions from observed phenonena is a hazard of back yard horticulture. But, if the results are to my liking, the truth is of little importance to me personally. To expound upon falacious conclusions to my contemporaries might, however, be sinful.

  Since the damage to insects is strictly physical rather than chemical, I doubt the purity of the water diatomaceous organisms lived in is terribly important. Much of the present supply is mined from deposits in Arkansas. These were deposited over millions of years in early geological periods while virtually the entire continent was a shallow dead sea unlikely to be very fresh.

  But whatever! Diatomaceous earth is a fairly effective natural (if cruel), non-chemical insect control that is probably under-used in the home and garden. Buy your DE at any nursery outlet on or off-line packaged for agricultural use, follow the directions and warnings on the package and forget about its origin. We can use it without any significance harm to the environment without debating its history.

  I believe DE is relatively safe but I have read that breathing a lot of it can make one uncomfortable.

  Dick Gross

  PS: An experts opinion might help clarify the discussion on this subject.

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  ----- Original Message ----- 

  From: "Suzanne Vilardi" <suz at vilardi.com>

  To: <arid_gardener at CALS.arizona.edu>

  Sent: Monday, July 31, 2006 5:43 PM

  Subject: [Arid_gardener] Diatomaceous Earth - Fresh Water VS Salt Water

  > Yesterday someone recommended buying Diatomaceous Earth (DE) at pool stores
  > for use in the garden.  I am not a master gardener and have just started
  > using DE in my garden but have been told numerous times NOT to use the pool
  > store type.  According to the Website:
  > http://www.reade.com/Products/Minerals_and_Ores/diatomaceous_earth.html,
  > 
  > There are 2 types of DE, salt water and fresh water.  I am pretty sure the
  > type sold in pool stores is salt water and the type sold at Berridge
  > Nurseries and Baker Nursery is fresh water.  I also think the salt water DE
  > may be more toxic to dogs and cats. Perhaps an expert Master Gardener can
  > set us straight?
  > 
  > FYI, I just saw garden suitable DE at Berridge Nurseries yesterday.  They
  > are located at 4647 E. Camelback, phone is 602.952.8080.  They were well
  > stocked with packaged seed too, unlike Baker's and Summer Winds, who don't
  > seem to have restocked yet.  Rgds, Suzanne Vilardi
  > 
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