Diatomaceous earth: Difference between revisions

[[File:DiatomaceousDiatomite Earth(Sisquoc Formation, Miocene-Pliocene; Palos Colorados Quarry, California, USA) 5.jpg|thumb|upright=1.2|ADiatomite rock sample of food-gradefrom diatomaceous[[Sisquoc earthFormation]]]]

'''Diatomaceous earth''' ({{IPAc-en|ˌ|d|aɪ|.|ə|t|ə|ˈ|m|eɪ|ʃ|ə|s}} {{respell|DY|ə|tə|MAY|shəs}}), also known as '''diatomite''' ({{IPAc-en|d|aɪ|ˈ|æ|t|ə|m|aɪ|t}} {{respell|dy|AT|ə|myte}}), '''celite''', or '''kieselgur'''/'''kieselguhr''', is a naturally occurring, soft, [[siliceous rock|siliceous]] [[sedimentary rock]] that can be crumbled into a fine [[shades of white|white to off-white]] powder. It has a [[particle size]] ranging from more than 3&nbsp;[[millimeter|mm]] to less than 1&nbsp;[[micrometre|μm]], but typically 10 to 200&nbsp;μm.<ref>{{Cite journal |last1=Dobrosielska |first1=Marta |last2=Dobrucka |first2=Renata |last3=Brząkalski |first3=Dariusz |last4=Frydrych |first4=Miłosz |last5=Kozera |first5=Paulina |last6=Wieczorek |first6=Monika |last7=Jałbrzykowski |first7=Marek |last8=Kurzydłowski |first8=Krzysztof J. |last9=Przekop |first9=Robert E. |date=May 18, 2022 |title=Influence of Diatomaceous Earth Particle Size on Mechanical Properties of PLA/Diatomaceous Earth Composites |journal=Materials |language=en |volume=15 |issue=10 |pages=3607 |doi=10.3390/ma15103607 |doi-access=free |issn=1996-1944 |pmc=9145730 |pmid=35629631|bibcode=2022Mate...15.3607D }}</ref> Depending on the [[granularity]], this powder can have an [[abrasive]] feel, similar to [[pumice]] powder, and has a low [[density]] as a result of its high [[porosity]]. The typical chemical composition of oven-dried diatomaceous earth is 80–90% [[silica]], with 2–4% [[aluminum oxide|alumina]] (attributed mostly to [[clay mineral]]s), and 0.5–2% [[iron oxide]].<ref name="USGS">{{cite book |last=Antonides |first=Lloyd E. |title=Diatomite |year=1997 |publisher=[[United States Geological Survey|USGS]] |url=https://minerals.usgs.gov/minerals/pubs/commodity/diatomite/250497.pdf |access-date=December 12, 2010}}</ref>

Diatomaceous earth consists of the [[fossil]]ized remains of [[diatom]]s, a type of hard-shelled [[microalgae]], that have accumulated over millions of years.<ref name=":0">{{Cite journal |last1=Rojht |first1=Helena |last2=Horvat |first2=Aleksander |last3=Athanassiou |first3=Christos G. |last4=Vayias |first4=Bill J. |last5=Tomanović |first5=Željko |last6=Trdan |first6=Stanislav |date=2010–2012 |title=Impact of geochemical composition of diatomaceous earth on its insecticidal activity against adults of Sitophilus oryzae (L.) (Coleoptera: Curculionidae) |url=http://link.springer.com/10.1007/s10340-010-0313-6 |journal=Journal of Pest Science |language=en |volume=83 |issue=4 |pages=429–436 |doi=10.1007/s10340-010-0313-6 |bibcode=2010JPesS..83..429R |s2cid=23110767 |issn=1612-4758}}</ref> It is used as a [[filtration]] aid, mild abrasive in products including metal polishes and [[toothpaste]], mechanical [[insecticide]], [[absorption (chemistry)|absorbent]] for liquids, matting agent for coatings, reinforcing filler in plastics and rubber, anti-block in plastic films, porous support for chemical catalysts, [[Litter box|cat litter]], activator in [[coagulation]] studies, a stabilizing component of [[dynamite]], a [[thermal insulation|thermal insulator]], and a soil for potted plants and trees as in the art of [[bonsai]].<ref>{{cite journal |last1=Reka |first1=Arianit A. |last2=Pavlovski |first2=Blagoj |last3=Ademi |first3=Egzon |last4=Jashari |first4=Ahmed |last5=Boev |first5=Blazo |last6=Boev |first6=Ivan |last7=Makreski |first7=Petre |title=Effect Of Thermal Treatment Of Trepel At Temperature Range 800-1200˚C |journal=Open Chemistry |date=December 31, 2019 |volume=17 |issue=1 |pages=1235–1243 |doi=10.1515/chem-2019-0132|doi-access=free }}</ref><ref>{{cite journal |last1=Reka |first1=Arianit |last2=Anovski |first2=Todor |last3=Bogoevski |first3=Slobodan |last4=Pavlovski |first4=Blagoj |last5=Boškovski |first5=Boško |title=Physical-chemical and mineralogical-petrographic examinations of diatomite from deposit near village of Rožden, Republic of Macedonia |journal=Geologica Macedonica |date=December 29, 2014 |volume=28 |issue=2 |pages=121–126 |url=https://js.ugd.edu.mk/index.php/GEOLMAC/article/view/920}}</ref> It is also used in [[gas chromatography]] packed columns made with glass or metal as stationary phase.

EachDiatomaceous depositearth consists of diatomaceousthe earthfossilized isremains different,of withdiatoms varyingthat blendsaccumulated over millions of pureyears. diatomaceousIt earthusually combinedcomprises with80% otherto natural90% clayssilica, and2% to 4% alumina minerals, and 0.5% to 2% iron oxide, although the precise composition of every deposit is different.<ref name=":0" /> The diatomsDeposits in each depositmay contain different amounts of silica, depending on the [[sedimentology|sedimentation conditions]], on the presence of other sediments (clay, sand, volcanic ashes), and on the age of the deposit ([[diagenesis]], [[silica]] (SiO₂) dissolution/precipitation, diatoms tests ageing). The species of diatom may also differ among deposits. The species of diatom is dependent upon the age and [[paleoecology]] of the deposit. In turn, the shape of a diatom is determined by its species.

In 1836 or 1837, German peasant Peter Kasten discovered diatomaceous earth (German: ''Kieselgur''{{--)}} when sinking a well on the northern slopes of the [[Haußelberg]] hill, on [[Lüneburg Heath]] in [[North German Plain|North Germany]].<ref>{{cite journalbook |last1=Ghobara |first1=Mohamed M |last2=Mazumder |first2=Nirmal |last3=Vinayak |first3=Vandana |last4=Reissig |first4=Louisa |last5=Gebeshuber |first5=Ille C |last6=Tiffany |first6=Mary Ann |last7=Gordon |first7=Richard |last8=Gordon |first8=Richard |title=On Light and Diatoms: A Photonics and Photobiology Review |journal=Diatoms: Fundamentals and Applications |date=June 28, 2019 |page=475 |doi=10.1002/9781119370741.ch7|isbn=9781119370215 |s2cid=202096365 }}</ref><ref name="Nobel">{{cite web | url=https://www.humboldt-foundation.de/kosmos/kultur/2001_002.htm | title=Deutschland - Wiege des Nobelpreis: Tourismus-Industrie und Forschung auf den Spuren Alfred Nobels | publisher=[[Alexander von Humboldt Foundation]] | date=December 17, 2001 | access-date=October 12, 2018 | last=Klebs | first=Florian | language=de| archive-url=https://web.archive.org/web/20021117030549/https://www.humboldt-foundation.de/kosmos/kultur/2001_002.htm | archive-date=November 17, 2002 }}</ref>

In 1866, [[Alfred Nobel]] discovered that [[nitroglycerin]] could be made much more stable if absorbed in diatomite (''kieselguhr'' in German).<ref>{{Cite web |title=Nitroglycerine and Dynamite |url=https://www.nobelprize.org/alfred-nobel/nitroglycerine-and-dynamite/ |access-date=November 27, 2023 |website=NobelPrize.org |date=June 11, 2013 |language=en-US}}</ref> This allowed much safer transport and handling than pure nitroglycerin under thein liquid form. Nobel patented this mixture as [[dynamite]] in 1867; the mixture is also called guhr dynamite in reference to the kieselguhr.<ref>{{cite book |last=Rustan |first=Agne |title=Rock Blasting Terms and Symbols: A Dictionary of Symbols and Terms in Rock Blasting and Related Areas like Drilling, Mining and Rock Mechanics |url=https://books.google.com/books?id=S0FZDwAAQBAJ&q=guhr&pg=PA83 |date=February 1, 1998 |publisher=Taylor & Francis |isbn=978-1-4665-7178-5 |page=83}}<br /ref><ref>{{cite book |last=Bulson |first=P.S. |title=Explosive Loading of Engineering Structures |url=https://books.google.com/books?id=U02uDwAAQBAJ&q=guhr&pg=PA3 |date=July 24, 1997 |publisher=CRC Press |isbn=978-1-135-82980-3 |page=3}}</ref>

This also works against [[gastropod]]s and is commonly employed in gardening to defeat [[slug]]s.<ref>{{cite web |title=Using Diatomaceous Earth for Slugs |url=https://www.slugcuisine.co.uk/diatomaceous-earth/ |website=Slug Cuisine}}</ref> However, since slugs inhabit humid environments, efficacy is very low. Diatomaceous earth is sometimes mixed with an attractant or other additives to increase its effectiveness.

[[Medical-grade]] diatomite has been studied for its efficacy as a [[deworming]] agent in cattle; in both studies cited the groups being treated with diatomaceous earth did not fare any better than control groups.<ref name="Lartigue 2004 660–674">{{cite journal |last1=Lartigue |first1=E. del C. |last2=Rossanigo |first2=C. E. |year=2004 |title=Insecticide and anthelmintic assessment of diatomaceous earth in cattle |journal=Veterinaria Argentina |volume=21 |issue=209 |pages=660–674 }}</ref><ref name="Fernandez 1998 635–641">{{cite journal |last1=Fernandez |first1=M. I. |last2=Woodward |first2=B. W. |last3=Stromberg |first3=B. E. |year=1998 |title=Effect of diatomaceous earth as an anthelmintic treatment on internal parasites and feedlot performance of beef steers |journal=Animal Science |volume=66 |issue=3 |pages=635–641 |doi=10.1017/S1357729800009206 }}</ref> It is commonly used in lieu of [[boric acid]] and can be used to help control and possibly eliminate [[Cimex|bed bugs]],<ref>{{Cite web |date=October 29, 2020 |title=Bed Bug Control With Diatomaceous Earth |url=https://www.absorbentproductsltd.com/bed-bug-control-with-diatomaceous-earth/ |access-date=October 29, 2020 |website=Absorbent Products |archive-date=November 4, 2020 |archive-url=https://web.archive.org/web/20201104022609/https://www.absorbentproductsltd.com/bed-bug-control-with-diatomaceous-earth/ |url-status=dead }}</ref> [[house dust mite]], [[cockroach]], [[ant]], and [[flea]] infestations.<ref name="Faulde">{{cite journal |first1=M. K. |last1=Faulde |first2=M. |last2=Tisch |first3=J. J. |last3=Scharninghausen |title=Efficacy of modified diatomaceous earth on different cockroach species (Orthoptera, Blattellidae) and silverfish (Thysanura, Lepismatidae) |journal=Journal of Pest Science |date=August 2006 |volume=79 |issue=3 |pages=155–161 |doi=10.1007/s10340-006-0127-8 |bibcode=2006JPesS..79..155F |s2cid=39203675 }}</ref>

In order to be effective as an insecticide, diatomaceous earth must be [[calcination|uncalcinated]] (i.e., it must not be heat-treated prior to application)<ref>{{Cite book|title=Encyclopedia of Entomology|last=Capinera|first=John L.|editor1-last=Capinera|editor1-first=John L.|edition=Second|year=2008|page=1216|chapter=Diatomaceous earth|publisher=Springer|chapter-url=https://books.google.com/books?id=i9ITMiiohVQC|isbn=978-1-4020-6242-1}}</ref>{{Better source needed|reason=This secondary source implies the claim, but doesn't explicitly state it, and it lacks supporting explanations and inline citations. Action: verify references in secondary source.|date=October 2024}} and have a mean particle size below about 12&nbsp;μm (i.e., food grade—[[#Specific varieties|see below]]).{{Citation needed|date=October 2024}}

=== Home Goodsgoods ===

Inhalation of ''crystalline'' silica is harmful toharms the lungs, causing [[silicosis]]. ''Amorphous'' silica is considered to have low toxicity, but prolonged inhalation causes lung changes to the lungs.<ref>{{cite web|url=https://www.cdc.gov/niosh/pel88/68855-54.html|title=NIOSH 1988 OSHA PEL Project Documentation: List by Chemical Name: SILICA, AMORPHO|date=September 19, 2018|publisher=CDC}}</ref> Diatomaceous earth is mostlymainly [[amorphous silica]] but contains some crystalline silica, especially in the saltwater forms.<ref>{{cite web |url=https://www.spca.bc.ca/assets/documents/welfare/professional-resources/farmer-resources/diatomaceous-earth-factsheet.pdf |title=Diatomaceous Earth: Its Use and Precautions |access-date= November 9, 2013 |url-status=dead |archive-url=https://web.archive.org/web/20130717171434/https://www.spca.bc.ca/assets/documents/welfare/professional-resources/farmer-resources/diatomaceous-earth-factsheet.pdf |archive-date=July 17, 2013 }}</ref> In a 1978 study of workers, those exposed to natural diatomaceous earth for over five years had no significant lung changes while 40% of those exposed to the calcined form had developed [[pneumoconiosis]].<ref>{{cite web|url=https://www.cdc.gov/niosh/docs/81-123/pdfs/0552.pdf |date=September 1978 |title=Occupational Health Guideline for Amorphous Silica |work=[[Centers for Disease Control and Prevention|CDC]] |access-date=March 24, 2020 |url-status=live |archive-url=https://web.archive.org/web/20200312013339/https://www.cdc.gov/niosh/docs/81-123/pdfs/0552.pdf |archive-date=March 12, 2020}}</ref> Today's commonstandard diatomaceous earth formulations are safer to use, as they are predominantly made up of amorphous silica and contain little or no crystalline silica.<ref name="Inert Dusts"/>

The crystalline silica content of diatomaceous earth is regulated in the United States by the [[Occupational Safety and Health Administration]] (OSHA). and thereThere are guidelines from the [[National Institute for Occupational Safety and Health]] that set maximum amounts allowable in the product (1%) and in the air near the breathing zone of workers, with a [[recommended exposure limit]] at 6&nbsp;mg/m³ over an 8-hour workday.<ref name="Inert Dusts">{{cite web|url=https://www.oznet.ksu.edu/grsc_subi/Teaching/GRSC651/GRSC651_Courses_Material/lecture_slides/GRSC651_lect_20(1)_Inert_Dusts.pdf|date=July 10, 2003|title=Inert Dusts|author1=Bhadriraju Subramanyam|author2=Rennie Roesli|archive-url=https://web.archive.org/web/20030710215341/https://www.oznet.ksu.edu/grsc_subi/Teaching/GRSC651/GRSC651_Courses_Material/lecture_slides/GRSC651_lect_20(1)_Inert_Dusts.pdf|archive-date=July 10, 2003}}</ref> OSHA has set a [[permissible exposure limit]] for diatomaceous earth as 20 mppcf (80&nbsp;mg/m³/%SiO₂). At levels of 3,000&nbsp;mg/m³, diatomaceous earth is immediately dangerous to life and health.<ref>{{Cite web|title = NIOSH Pocket Guide to Chemical Hazards - Silica, amorphous|url = https://www.cdc.gov/niosh/npg/npgd0552.html|publisher=CDC|access-date = November 21, 2015}}</ref>