Editing Litter box (section)

==Types of litter box filler==
[[Ed Lowe (businessman)|Edward Lowe]] accidentally discovered that clay made an excellent cat litter material and began selling it in bags as "Kitty Litter" in 1947.<ref>{{Cite journal |date=January 1987 |title=Self drying pet litter box |url=http://dx.doi.org/10.1016/0160-4120(87)90019-5 |journal=Environment International |volume=13 |issue=6 |pages=II |doi=10.1016/0160-4120(87)90019-5 |issn=0160-4120|url-access=subscription }}</ref>  In the US, cat litter is a $2 billion industry consuming {{convert|5|e9lb||spell=in|}} of mined clay annually.<ref>{{cite news |last1=Gross |first1=Daniel |title=How Kitty Litter went from happy accident to $2 billion industry |url= https://www.washingtonpost.com/national/health-science/you-wont-believe-how-old-that-kitty-litter-is/2015/02/02/9ecac9ea-a1b4-11e4-903f-9f2faf7cd9fe_story.html |access-date=18 July 2017 |newspaper=[[The Washington Post]] |date=2 February 2015 |archive-url=http://web.archive.org/web/20151112232741/https://www.washingtonpost.com/national/health-science/you-wont-believe-how-old-that-kitty-litter-is/2015/02/02/9ecac9ea-a1b4-11e4-903f-9f2faf7cd9fe_story.html |archive-date=12 November 2015}}</ref>

===Non-clumping conventional litter===
The first commercially available cat litter in the United States was ''Kitty Litter'', available in 1947 and marketed by [[Ed Lowe (businessman)|Ed Lowe]]. This was the first large-scale use of [[clay]] (in the form of [[Fuller's earth]]) in litter boxes; previously [[sand]] was used. Clay litter is much more absorbent than sand and is manufactured into large grains or clumps of clay, making it less likely to be tracked from the litter box. The brand name ''Kitty Litter'' has become a [[genericized trademark]], used by many to denote any type of cat litter. Today, cat litter can be obtained at a variety of retail stores. Non-clumping cat litter is often made of [[zeolite]], [[diatomite]] and [[sepiolite]].<ref>{{cite web |title=Clumping cat litter Vs. Non-clumping: What's the difference? |url=https://catthink.com/best-clumping-cat-litter/ |website=CatThink |date=18 April 2020}}</ref>

===Clumping litter===
====Clay====
[[File:Fig.1.SEM-image of cat litter.jpg|thumb|Microscopic close-up of clumping cat litter, showing the fossilized remains of [[diatom]]s]]
Litter clumps were first developed by using [[calcium bentonite]] clay. This was manufactured in the UK in the 1950s by the Fuller's Earth Union (FEU), which later became a part of Laporte Industries Ltd. Subsequently in America, clumping bentonite was developed in 1984 by biochemist Thomas Nelson.<ref>{{cite news |url= http://www.biscaynetimes.com/index.php?option=com_content&view=article&id=2147:soaking-up-the-history-of-cat-litter&catid=82:pet-talk&Itemid=247 |title=Soaking Up the History of Cat Litter |work=Biscayne Times |access-date=4 November 2016}}</ref> Most are made from granulated [[Bentonite|bentonite clay]], which clumps together when wet and forms a solid mass separate from the other litter in the box. This solid clumped material can be scooped out and disposed of without changing the entire contents of the litter box.

Clumping litter usually also contains [[quartz]] or [[diatomaceous earth]] (sometimes called diatomaceous silica, which causes it to be mistakenly confused with silica gel litter). Because of the clumping effect, the manufacturers usually instruct not to flush clumping litters down the toilet, because it could clog it.<ref name="cats">{{cite web |url= http://cats.about.com/cs/litterbox/a/clumpingclay.htm |title=Cat Litter – To Scoop or Not to Scoop: The Clumping Clay Controversy |access-date=30 April 2015}}</ref>

Clumping clay cat litters are natural products. Some may also contain naturally occurring [[crystalline silica]], or silica dust, which in California is treated as a known carcinogen under [[California Proposition 65 (1986)|Proposition 65]].<ref name="prop65">{{cite web |url= http://www.calprop65.com/99regs.html |title=1999 Prop 65 Regulatory Update |access-date=30 November 2008 |archive-url=https://archive.today/19991023135307/http://www.calprop65.com/99regs.html |archive-date=23 October 1999 |url-status=dead}}</ref> Clay litter is also criticized by the manufacturers of non-clay litter because the components of clay litter are commonly obtained from a [[strip mine]] in an environmentally degrading process.<ref>{{cite web |last=Donge |first=Lily |url=https://groundswell.org/kitty-litter-not-6-cheap-ways-to-reduce-your-pets-environmental-impact/ |title=Kitty, Litter Not! 6 Cheap Ways to Reduce Your Pet's Environmental Impact |publisher=Groundswell |date=22 October 2009 |access-date=4 April 2020}}</ref>
<ref>{{cite web |url= https://fullpaw.com/environmental-impact-of-cat-litter/ |title=The Environmental Impact of Cat Litter |website=FullPaw.com |date=20 June 2023 |access-date=20 June 2023}}</ref>

This sort of litter can be toxic to [[ferret]]s, leading to both respiratory and digestive problems.<ref>{{cite web |url= https://www.ferret.org/pdfs/education/bestlitter.pdf |title=Choosing litter for your ferret |date=2015 |work=Ferret.org |publisher=American Ferret Association}}</ref>

====Non-clay====
Minerals Technologies offers a clumping cat litter in the form of crystals made of "compacted [[Sodium bicarbonate|baking soda]]",{{r|MT}} which in contrast to bentonite is either [[dust]]-free{{r|MT}} or low-dust,{{r|PH}} and allegedly "100% [[Carbon dioxide|CO<sub>2</sub>]] [[Greenhouse gas emissions|neutral]]".{{r|PH}}{{Better source needed|date=May 2024}}

===Biodegradable litter===
Biodegradable litters are made from various plant resources, including pine wood pellets, recycled newspaper, clumping sawdust, Brazilian cassava, pea husk, corn, wheat, walnuts, barley, [[soy pulp]], and dried orange peels.

Each year, more than two million tons of cat litter ends up in landfills in the US alone. Primarily, this is not biodegradable or renewable and adds to the waste burden.<ref>{{cite book |first=Judd |last=Alexander |title=In Defense of Garbage |publisher=Praeger |date=1993|isbn=0275936279|page=60}}</ref> Some pet owners prefer biodegradable litters due to its friendliness to the environment. Biodegradable cat litter can also be eliminated completely by safely [[composting]] the used litter at home. Other cat owners can be attracted to the biodegradable litters because of their flushability or deodorizing properties.<ref>{{cite news |url= http://www.guardian.co.uk/environment/2006/sep/23/practicaladvice.ethicalliving |title=Tackling the carbon pawprint |access-date=30 November 2008 |work=[[The Guardian]] |location=London |date=23 September 2006 |first=Dave |last=Hall}}</ref> Some pets, such as those with [[asthma]] or sensitive senses of smell, may also benefit from the reduced dust in some forms of biodegradable litter.

Biodegradable litter packaged for cats tends to be more expensive than traditional clay litters, so cost is often not a positive factor in their selection. Most biodegradable litters last longer than the equivalent clay or clumping clay litters.<ref>{{cite journal |url=https://welovecatsandkittens.com/cat-litter/eco-friendly-cat-litter/|date=24 November 2024 |title=Best Eco-Friendly Cat Litter (2024): 6 Top Sustainable Choices }}</ref> Grain-based animal or poultry feed also provides an economical alternative to products marketed specifically as cat litter. Additionally, most of these forms of litter are recycled from human usage and are thus reusing a waste product as opposed to drawing clay from mines.

[[Guar gum]] was the principal clumping agent used in biodegradable cat litter as of 2013,{{sfn|Vaughn|Kenar|Felker|Berhow|2013|p=798}} with a clumping rate of 69.8%, while [[xanthan gum]] (73.9%) and [[plantago]] [[Natural gum|gum]] (57.5%) were identified in one study as potential alternatives.{{sfn|Vaughn|Kenar|Felker|Berhow|2013|p=800}}{{r|AG}} It is also added to bentonite litter to increase its clumping capacity.{{r|AG1}} In 2020, it was still being used in tests of new wood-based biodegradable litter formulations.{{sfn|Vaughn|Winkler-Moser|Berhow|Byars|2020|p=4}}

===Silica gel litter===
[[File:Kattengrit-2.jpg|thumb|right|Silica "crystal" litter]]
[[Silica gel]] litter, often referred to as "crystal litter", is a porous granular form of [[silicon dioxide]], has the highest absorbency of any litter, and has excellent moisture control and complete odor elimination for an extended period of time compared to other litters. It is typically prepared through a sol-gel process, which involves the hydrolysis and condensation of silica precursors such as tetraethylorthosilicate (TEOS) or sodium silicate (Na2SiO3).<ref>{{Cite journal |last=Demirdöğen |first=R. E. |title=Chemical Synthesis Method for Production of Silica Gel as a Sorbent Material |s2cid=208628750 }}</ref> The porous structure of silica gel enables it to trap moisture within its network of interconnected pores, effectively locking away urine and preventing it from spreading or leaking. Moreover, many silica gel litter formulations incorporate activated carbon or other odor-neutralizing compounds, which further enhance the litter's ability to control unpleasant smells.<ref>{{Cite journal |last1=Zhuang |first1=Guo-Liang |last2=Tseng |first2=Hui-Hsin |last3=Wey |first3=Ming-Yen |date=October 2014 |title=Preparation of PPO-silica mixed matrix membranes by in-situ sol–gel method for H2/CO2 separation |url=http://dx.doi.org/10.1016/j.ijhydene.2014.08.050 |journal=International Journal of Hydrogen Energy |volume=39 |issue=30 |pages=17178–17190 |doi=10.1016/j.ijhydene.2014.08.050 |issn=0360-3199|url-access=subscription }}</ref> In addition to its physical structure, the chemical composition of silica gel also contributes to its performance as a cat litter. The surface of silica gel is covered with silanol (Si-OH) and siloxane (Si-O-Si) functional groups.<ref>{{Cite journal |last1=Meti |first1=Puttavva |last2=Wang |first2=Qi |last3=Mahadik |first3=D. B. |last4=Lee |first4=Kyu-Yeon |last5=Gong |first5=Young-Dae |last6=Park |first6=Hyung-Ho |date=January 2023 |title=Evolutionary Progress of Silica Aerogels and Their Classification Based on Composition: An Overview |journal=Nanomaterials |language=en |volume=13 |issue=9 |pages=1498 |doi=10.3390/nano13091498 |doi-access=free |pmid=37177045 |pmc=10180228 |issn=2079-4991}}</ref> These groups interact with water molecules through hydrogen bonding and dipole-dipole interactions, enabling the material to absorb and retain moisture effectively.<ref>{{Cite journal |doi=10.1016/j.apsusc.2023.158616 |s2cid=263687166 |title=Dominant factors for moisture resistance of sol–gel silica coatings: Surface chemical composition or inner microstructure? |date=2024 |last1=Zhang |first1=Chen |last2=Wang |first2=Hongqiang |last3=Shen |first3=Jun |last4=Wang |first4=Xiaodong |journal=Applied Surface Science |volume=642 |bibcode=2024ApSS..64258616Z }}</ref>

Some owners praise its absorbency because {{convert|4|-|5|lb|kg}} can absorb liquid and odor for up to 30 days for one healthy normal weight cat.{{citation needed|date=December 2018}} It is important to lightly stir the crystals daily while scooping the solid waste, otherwise urine can pool in the box. When crystal litter is saturated, at the end of 30 days or so, it begins to smell and is visibly saturated (the white crystals have turned slightly yellow). In comparison, over the same time period it may take {{convert|20|–|30|lb|kg|abbr=on}}{{Citation needed|date=August 2019}}<ref>{{cite web |url= http://pets.thenest.com/liquid-absorbing-properties-cat-litter-9654.html |title=Liquid Absorbing Properties of Cat Litter |last=Anne |first=Melodie |website=Pets.TheNest.com |access-date=2 August 2019}}</ref> or more of clay or clumping litter, because it is necessary to replenish the litter that is removed when the clumped urine is scooped out. No replenishing is necessary with silica gel (crystal) litter.