Digging Deeper:
The Scoop on Cat Litter


The Question

I have two cats and currently use clumping clay litter in their litter box. I have tried to use cat litter made from recycled newsprint, but Gravy and Tang would not use it. What are other environmentally friendly alternatives I could try?

The Explanation
What is clay clumping cat litter and how does it work? Prior to the 1950s, most cat owners only had two options: open the door to let their cats “do their business” outside, or provide an indoor box of ashes or sand. These choices both had adverse impacts.  Inside homes, cats tracked dirt and ashes; outside, they followed their predatory instincts, killing birds, reptiles, and small mammals. In 1947, a neighbor asked Edward Lowe, who at the time worked for his father’s industrial absorbents business in Michigan, if he knew of an absorbent material she could put in her cat box. Lowe supplied her with dried clay, subsequently developed the concept into a successful business, and made pet care history along the way. Today, more than one-third of American households keep cats as pets, and cat litter is a billion dollar industry.

In 1984, Baylor University biochemist and cat lover Thomas Nelson observed that bentonite clay formed clumps in the presence of moisture. Bentonite is a clay mineral composed largely of silicate, aluminum, magnesium, and iron. Its chemical structure attracts water and ammonia molecules, making bentonite an excellent absorbent and odor control agent. More than 75 percent of cat litters on the market are made from bentonite clay. These litters are extremely popular because bentonite’s clumping property isolates solid and liquid waste, allowing pet owners to easily scoop out used material and leave only clean litter behind.

Sources: Brady, Diane, and Christopher Palmeri. “The Pet Economy.” Business Week August 6, 2007.
Moser, Penny Ward. “Filler's The Name, Odor's The Game.” Fortune April 25, 1988..
Yarnell, Amanda. “Kitty Litter.” Chemical & Engineering News April 26, 2004. (Available at: http://pubs.acs.org/cen/whatstuff/stuff/8217kitty.html)

What are alternative cat litters and how do they work?Several alternative cat litters provide the same function as clay clumping cat litter, but are manufactured from more environmentally responsible materials. Some are even designed to be flushed down the toilet, reducing the landfill volume occupied by cat litter.

Recycled paper litters: Paper is highly absorbent, as demonstrated by household products such as paper towels and facial tissues. During the newspaper recycling process, newsprint is de-inked, screened, and pulped. While long newsprint fibers can be recycled as future newspaper, short fibers are typically considered waste. When dried, formed into pellets, and combined with an odor control agent, short newsprint fibers can have a ninth life as cat litter. Paper-based litter is lightweight, extremely absorbent, and can be flushed down the toilet instead of consigned to landfill. Popular cat litters made from recycled newsprint include the brands Yesterday’s News and Good Mews.

Wood litters: Recycled waste from the lumber industry is also used to make cat litter; one popular example is Feline Pine. Byproducts like sawdust, bark, and scrap are finely ground, then heated to over 1200°F, which causes tree sap to bind the wood into pellets. A benefit of pine is its scent, which may effectively control cat waste odors.

Plant-based litters: Hard grains, like wheat, can be ground to a fine consistency and then made into pellets. Similarly, corncobs (such as those used in One Earth Cat Litter) and whole corn kernels (used in the brand World’s Best Cat Litter) can be ground, heated, and made into pellets, resulting in a lightweight, absorbent, flushable (or biodegradable) litter. Grain and corn-based litters contain natural enzymes that reportedly neutralize cat waste odors. Other plant-based litters use sunflower seeds, kenaf (a plant related to cotton and okra), green tea leaves, potato starch, and wheatgrass, but these are not widely available.

Sources: Alexander, Kelly. “The scoop on newfangled cat litter.” Slate, August 9, 2002. (Available at http://www.slate.com/default.aspx?id=2069161)
Dadd, D.L. “Healthy Cat Litter Alternatives.” In: Dadd, D.L. Home Safe Home. Penguin Putnam: New York, NY, 1997.
Hall, S.B. “Cat Litter.” In Blachford, S.L. (ed). How Products Are Made. eNotes.com: 2006. (Available at: www.enotes.com/how-products-encyclopedia/cat-litter.)
McNally, Shelagh. “Bad kitty litter, bad!” GreenLivingOnline, July 30, 2007. (Available at: http://www.greenlivingonline.com/HomeGarden/bad-kitty-litter-bad)

Life-Cycle Analysis

Raw Materials
Nearly all bentonite clay mined in this country is obtained by strip mining. According to the United States Geological Survey, approximately, 25 percent -- nearly 1,200 tons --  was used as a pet waste absorbent in 2005.

Strip mining is a surface mining practice with a long history of causing environmental damage. In the first stage of the mining process, engineers identify valuable mineral deposits that are 30 to 40 feet below the ground. Next, bulldozers remove any trees and bushes growing above the deposits, and excavate the topsoil and dirt down to the first rock layer. Vegetation, topsoil, and dirt are then dumped nearby. Depending on the type of mineral being mined, the next stage may be to drill small holes through the freshly uncovered rock. Explosives are put into the holes and detonated, breaking up the rock, which is also then dumped. Eventually, strip mining produces a series of pits from which mineral deposits are extracted, and a massive pile of discarded matter.



Photo by John Carlton, 2004.  Available via the Kansas Geological Survey Educational Resources


Modern strip mining practices have been modified to reduce their environmental impact. In many states, mining operations are legally required to re-establish plant and animal communities similar to those that lived on the site before it was mined. This is usually accomplished by filling mining pits with discarded vegetation, dirt, and rock fragments after the mineral deposit has been collected. In a process called reclamation, the newly filled pits are sown with fast-growing plants. Unfortunately, the plant communities that typically develop on reclaimed strip mines are not diverse enough to support animal communities like those at undisturbed sites. Many mining corporations and wildlife biologists are currently researching ways to improve reclamation practices.

Because many alternative cat litters use recycled materials or byproducts from other industries, acquiring the necessary raw materials usually has a much lighter environmental impact than acquiring the materials for clay-based litter.

Making It
To make clay-based kitty litter, raw clay is crushed into small pieces, baked in a kiln, mixed, and then crushed again. Finally, rollers crumble the clay into a variety of textures, and differently sized pellets are packaged and sealed. Making cat litter is an energy-intensive process, because it requires many kinds of machinery: two crushers, conveyor belts, a large kiln, a tumbler, rollers, screening machines, and pellet sorters. Alternative cat litters likely use similar amounts of energy during the manufacturing stage, because all cat litters have to be meticulously ground up or compacted to achieve the desirable consistency.

Using It
Regularly scooping clumped litter material out of a litter box prevents total saturation.  (Note that if a litter box becomes saturated, your cats will likely begin looking for other, drier places to do their business.) Manufacturers recommend changing the entire contents of a litter box every four to six weeks to prevent bacteria buildup; anecdotally, many users report changing out the contents more often. One practical problem with clay clumping litter is that its small pellets frequently stick to cats’ paws and “track” onto carpets and other textured indoor surfaces. Some alternative litters made from soft materials like corn and wheat may also track, but pellet litters made from recycled newsprint, or pine chips, usually don’t.

Disposal
Each year, more than 150,000 tons of cat litter end up in U.S. landfills. Because clumping is a chemical process, and clay litter contains mostly non-biodegradable materials, used clay litter simply accumulates in landfills. Some cat owners flush used clay litter down the toilet, although since clumping litter is deliberately designed to absorb moisture, this practice can result in serious sewer clogs.

Pet owners in coastal areas should think twice about flushing used litter. Domestic cats may carry the protozoan parasite Toxoplasmosis gondii , and may shed active oocysts, or spores, in their feces. These oocysts are not eliminated by current wastewater treatments, and flushing simply speeds them on their way to open bodies of water. Sea otters are particularly vulnerable to T. gondii, and recent studies have found that sea otters from areas of high freshwater runoff were three times more likely to contain T. gondii antibodies, indicating current or past infection. According to a study by scientists at the University of California at Davis,this parasite can kill sea otters. In addition, infected otters are almost three times more likely to suffer from cardiac disease, and are at a much higher risk of shark attack.



Above-- Sea otters living near cities may have a higher risk of T. gondii infection.

In short, if you and your cat live close to the coast, sending your used litter to the landfill is the best disposal option. Cat owners further from the seashore may want to try the more environmentally friendly method of flushing a biodegradable alternative cat litter.

Sources: Ireland. T.T., Wolters, G.L., and S.D. Schemnitz. 1994. Recolonization of Wildlife on a Coal Strip-Mine in Northwestern New Mexico. The Southwestern Naturalist 39(1): 53-57.
Parmenter, R.R, and J.A. MacMahon. 1990. Faunal community development on disturbed lands: an indicator of reclamation success. In: Chambers J.C., and G. L. Wade (eds.). Evaluating reclamation success: the ecological consideration. United States Department of Agriculture Forestry Service General Technical Report NE 164: Radnor, PA, 1990.
Schissler, A., and C.J. Cleveland. Strip mining. In: C.J. Cleveland (ed.) Encyclopedia of Earth. Environmental Information Coalition, National Council for Science and the Environment: Washington, D.C., 2006.

 The Cost  
Alternative cat litters are likely to cost a bit more than those consisting of bentonite clay, but many are budget-friendly in addition to being environmentally friendly.

Sample
Brand(s)

Fresh Step Premium Clay Cat Litter; Purina Tidy Cat Regular Clay Cat Litter Swheat Scoop Scoopable Cat Litter; Heartland Wheat Litter World's Best Cat Litter; Nature's Miracle Odor Control Clumping Cat Litter Feline Pine; ExquisiCat Enviro-Friendly Pine Litter Purina Yesterday's News Paper-Based Cat Litter; Good Mews

Eco-
Ingredient

Bentonite clay

Processed wheat

Whole kernel corn or ground orncobs

Scrap pine wood recycled from the lumber industry

Recycled newspaper

Sample Cost

$0.45 per pound

$0.55 per pound

$0.88 per pound

$0.60 per pound

$0.47 per pound

Disposal

Landfill

Flushable

Flushable

Flushable

Flushable

 

Habits
Most alternative cat litters are just as convenient as clay clumping litters, and do not require any kind of special maintenance. Some manufacturers claim their environmentally savvy products are more attractive to cats than clay litters, but that’s really for every pet and pet owner to decide.

The Rules
There are no laws governing the use of any kind of cat litter. Because of the risk that litter-borne parasites pose to marine animals, it’s safer to simply landfill cat litter in coastal areas.

For More Information
Hall, S.B. “Cat Litter.” In Blachford, S.L. (ed). How Products Are Made. eNotes.com: 2006. (Available at: www.enotes.com/how-products-encyclopedia/cat-litter.)
Moser, Penny Ward. “Filler's The Name, Odor's The Game.” Fortune April 25, 1988.
Shojaim, Amy D. "How Cat Litter Is Made." Cat Fancy Magazine, October 1994, pp. 12-14, 16, 18-19. (Available at: http://www.answers.com/topic/cat-litter-1?cat=technology.)
Yarnell, Amanda. “Kitty Litter.” Chemical & Engineering News April 26, 2004. (Available at:  http://pubs.acs.org/cen/whatstuff/stuff/8217kitty.html)


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