Ecological Footprint of Diapers

MaryKate Kroliczak

Environmental Issues Spring 2011

2 | P a g e

Abstract

The premise of this paper was to follow the process of producing a disposable and reusable

diaper and its ecological footprint it leaves on our planet. What I have discovered is that although the

process to make each product is very different neither commodity has limited environmental impacts.

There are three main components of a disposable diaper discussed; the super absorbent polymer that

makes up the inner core, the polyethylene non woven fabric that makes up the exterior of the diaper

and the cotton that is used as filler inside the diaper as well as the major component of reusable

diapers. The most important factor found in this study was that the amount of diaper changes required

by a child wearing disposable diapers will result in diapers decomposing for 6 times the average lifespan

of a person. The 7000 or so diapers my parents used on myself from June of 1986 to sometime in 1988

still have a remarkable 475 years until they are fully decomposed.

3 | P a g e

Contents Introduction ............................................................................................................................................ 4

History of Diapers .................................................................................................................................... 4

How Disposable Diapers are made .......................................................................................................... 7

Super Absorbent Polymers ...................................................................................................................... 8

Polyethylene ........................................................................................................................................... 9

Process of Making Cotton ...................................................................................................................... 10

Conclusion ............................................................................................................................................. 12

Appendix I ............................................................................................................................................. 13

Appendix II ............................................................................................................................................ 14

Appendix III ........................................................................................................................................... 15

Appendix III Continued .......................................................................................................................... 16

Works Cited ........................................................................................................................................... 17

4 | P a g e

Introduction

Consumerism, a noun created in 1945, is used to describe the interests of consumers and

promotes the notion that the consumption of goods is beneficial to our economy (Collins English

Dictionary , 2011). The role we play as consumers takes a harsh toll on our environment; our ever

growing population is degrading our natural resources and placing our existence in jeopardy all for the

sake of convenience.

Population Trends for the United States

According to the 2010 United States Census the population of the world is near 6.9 billion

individuals, the United States alone is home to 310 million consumers. The 2000 census tract states that

the average American household consists of 2.59 individuals and the average family size is 3.14

individuals (US Census Bureau). As stated in the Baby Deficit the replacement rate of the US is at 2.09,

and out of the 310 million people in the US approximately 20 million are under the age of five (Balter,

2006).

History of Diapers

Many cultures over time have experimented with the idea of a diaper. In ancient times animal

furs or large leaved plants acted as a protective barrier for a baby’s bottom. It wasn’t until the early

1800’s that the cloth diaper became popular, using a rectangular piece of cotton linen and a pin to

fasten. By the 1900’s cotton diapers had evolved and with the industrial revolution in full effect diaper

services became prevalent (The Diaper Jungle, 2011). The major issue with cotton diapers is that they

have poor absorbency and need to be laundered.

5 | P a g e

A revolutionizing invention took place in 1942 with the creation of the first disposable diaper.

This primitive diaper consisted of cellulose tissue and by 1946 a woman named Marion Donovan created

a water-proof cover called a boater. As the diaper revolution evolved companies went from using a

simple cellulose pad made up of wood pulp, cellulose, and cotton fiber to a complex polyacrylic acid

polymer surrounded by a polyethylene casing (The Diaper Jungle, 2011).

Statistics

A study conducted by the University of Michigan Health System states that most children begin

potty training between the ages of 24 to 27 months of age. The average age for females is 29 months

and for males approximately 31 months. The university states that by 32 months of age 98% of children

are fully potty trained (Kyla Boyse, 2010). Within the first year of a child’s life they will require

approximately 2,788 diaper changes that are roughly 232 diapers a month. If it takes the average child

32 months to be potty trained that means the child requires 7,424 diaper changes (Kids Growth.com).

Cloth Diapers

As stated earlier an average child needs about 7,400 diaper changes over a 2 ½ year time span.

It takes on average 30lbs of cotton to manufacture a cloth diaper and each diaper has an average life

span of about 4-5 months. Over this period of time an average child uses about 144 cloth diapers (Beil,

2004).

The environmental cost of a cloth diaper can be found by calculating the impacts of cotton

production as well as the cost of laundering these diapers. It is estimated that it takes 20,000 gallons to

launder diapers for the averaged span of time before potty training that is an average of 640 gallons per

month. If we use the American average household and state that each family constitutes 2 parents and

2 children on average 6% of water usage would be designated toward diaper washing (Beil, 2004).

6 | P a g e

Diaper services would be a slightly better option since they can handle a larger load and many machines

are fitted with a filtration system to remove solid waste before entering the washing system (Pham &

Brown, 2009). It was found that based on a weekly use of diapers reusable diapers used on average 120

more gallons of water than disposable and 50,000 more Btu’s (World Resources Institute, 1994).

Disposable Diapers

Disposable diapers account for 4% of total solid waste and 30% of non-biodegrable waste

generated. They are the 3rd largest single consumed item in waste system next to newspaper and

beverage containers (Beil, 2004). The US alone estimates 21 billion diapers reach landfills each year

(Cline, 2011). On average it takes a disposable diaper approximately 450 years to decompose in a landfill

(EPA, 2011). It is estimated that 82,000 tons of plastic is consumed by disposable diapers in the US alone

(Pham & Brown, 2009). On average the raw material consumption for a week of disposable diapers is

about 21lbs (World Resources Institute, 1994).

In 1978 the energy used in the manufacturing of disposable diapers was found to be greater

than the costs of washing a traditional cloth diaper (Pham & Brown, 2009). The cost of disposing diapers

is so great that some cities will subsidize the cost of cloth diapering or diaper services are encourage.

Seattle Solid Waste issued a grant to subsidized diaper services for low-income families. The research

behind this grant showed that it was cheaper to provide this service for families than it was to collect

and dispose of the excess garbage, on average it costs the municipality $400 to dispose of one child

diapered in disposables (Beil, 2004).

Dangers of Disposable Diapers

Disposable diapers are primarily used for convenience of a throw away item you won’t have to

look at again. Many parents are misinformed about the process of fecal waste. In the United States it is

7 | P a g e

illegal to dispose of human feces into a landfill and often time’s parents do not remove the bulk of fecal

matter from a disposable diaper. This fecal matter adds to the amount of bacteria found in landfills and

poses a threat of this bacteria leaching into groundwater systems (Gilbert, 2010).

A study in 1999 using three different brands found that rats exposed to emissions from the

decomposition of disposable diapers experienced impaired breathing. The study also identified m-

xylene, p-anisaldehyde, ethylbenzene, styrene, isoprophybenzene, dipentene, toluene and

trimethylcyclopentane in the emissions from two of the three brands of diapers. These dioxins from the

breakdown of disposable diaper can also leach into our groundwater systems (Gilbert, 2010).

How Disposable Diapers are made

Disposable diapers consist of an absorbent pad surrounded by two sheets of non-woven fabric.

The absorbent pad consists of a hydrophilic polymer typically made of polyacrylic acids such as acrylic

acid, sodium acrylate, potassium acrylate, and alkyl acrylate as well as natural fibers such as wood pulp

or cotton. These polymers act like tiny sponges on long ropes to absorb water quickly while the plant

pulp acts like a channel system to disperse the liquid evenly as to avoid gel blocking of these polymers

(How Products are Made, 2011).

The formation of the absorbent pad begins on a conveyer belt where pressurized nozzles spray

the polymer particles and fiber material onto an impermeable bottom sheet. The absorbent pad is then

vacuum sealed together using heat or ultra sonic vibrations (Appendix I). Three sheets of nonwoven

fabric consisting of polyethylene are then applied to pad forming the outer layer of the diaper then the

elastic bands for the legs are then attached (How Products are Made, 2011).

8 | P a g e

Super Absorbent Polymers

The main absorbency component for disposable diapers is super absorbent polymers. This

polymer is called polyacrylic acid and it was patented in 1966 by Dow Chemical and Johnson and

Johnson (Gilbert, 2010).These polymers are used as absorbers for aqueous solutions in that of diapers

and feminine hygiene products. They first became available commercially in Japan in 1978 and by 1980

European countries had developed these polymers for diapers (Peppas, 1994).

Production Process

In order to make the acrylic acid in which the SAP are made modern plants use a gas-phase

catalytic oxidation method which uses the oxidation of propylene to produce acrolein , acrylic acid,

acetaldehyde, and carbon oxides. The acrylic acid from phase one is removed and they use azeotropic

distillation to remove the rest to increase their yield. There are byproducts made from this process and

carbon oxides are formed as well (Mirasol, 2011).

Amount in Production

In a 1991 study provided by the United States Environmental Protection Agency stated that only

four acrylic acid producing plants existed in the US, three of which were located in Texas and one

located in Louisiana. The annual capacity for the US is 1.6 billion pounds of acrylic acid and in this study

1.1 billion pounds were produced, 75 million pounds exported, and 5 million imported from foreign

nations (Office of Pollution Prevention and Toxics, 1994).Currently in the US, Dow Chemical and

Chemdal Corporation are the largest producers of superabsorbent polymers and Stockhausen and

Nippon Shokubai are the world’s largest superabsorbent polymer producers (Graham, 1998). Super

absorbent polymers account for 21 percent of acrylic acid uses in the United States (Office of Pollution

Prevention and Toxics, 1994).

9 | P a g e

Transportation of Products

The United States Census Bureau produced a survey in 2007 tracking the transportation of

commodities. This extensive 254 page document calculated the amount, cost, and distance commodities

have traveled throughout the US. For Polymers 29,373 tons were produced and transported over 14,195

ton-miles 55% by truck 22% by rail and the remaining other modes of transportation (Transportation &

Commerce, 2007).

Environmental Stewardship

LG Chem of Korea has developed a process that employs a new reactor design that will minimize

the byproducts while improving the catalyst life as well as reducing size of equipment to ensure energy

savings. Rohm and Haas Chemical Corporation has been given a $5.2 million grant by the US Department

of Energy to renew catalyst oxidation to lower pollution produced as well as manufacturing costs

(Mirasol, 2011).

Polyethylene

The second component of a disposable diaper is the nonwoven material used to surround the

absorbent pad. This nonwoven material is made up of polyethylene. The process of making polyethylene

is derived from the modifying of natural gas (methane, ethane, & propane) or by the catalytic cracking

of crude oil into gasoline. In this purified form the polyethylene base is pipe directly from a refinery to a

polymerization plant. The next process requires specific temperature, pressure, and catalysts. This

process forms beads of polyethylene called pellets. These pellets are then distributed to various

companies which melt down the polyethylene from pellets and stretch them to form sheets (Appendix

II). Typically waste from polyethylene production is recycled in house or is sent to be repellitized

(Lepourte).

10 | P a g e

Over the last several decades the polyethylene market has seen some changes throughout their

manufacturing. The social aspect of throw away now to the notion of everything must be recycled has

caused these companies to reconsider methods of productions. The United States in 2009 produced 43

million tons of polyethylene plastics (Unite States Environmental Protection Agency, 2011).

Environmental Impacts

From the Inventory of US Greenhouse Gas Emissions and Sink report by the Environmental

Protection Agency the amount of CO2 produced by petrochemical production companies in 2009 was 2.7

teragrams. There has been a 17% percent decrease in carbon emissions by petrochemical producing

companies since the 90’s. Methane gas is a natural gas used in the process of making polyethylene as

well as a byproduct of the production process and in the 2009 study, petrochemical production resulted

in 0.8 Tg release (Environmental Protection Agency, 1990-2009).Plastics in primary form, which would

include polyethylene products, took 79,626 tons over a 51,457 ton-mile journey across US, 77% by truck

and 9% by rail (Transportation & Commerce, 2007).

Process of Making Cotton

Third main component for disposable diapers and one of the only components for reusable

diapers is cotton. Currently the United States uses 7.6 million bales of cotton for the manufacturing of

textile products, 57% is made into apparel (Cotton Counts). The journey of making raw cotton material

into a woven product is a lengthy 8 step process that takes an approximately six months. First the cotton

must be cultivated then comes harvesting, following this the cotton must be ginned to separate the

seed from the fiber. After the fiber is baled it is sent to be cleansed where the cotton is blown and beat.

The cotton fiber then gets carded which essentially pulls the fiber to make a continuous strand then it is

combed to makes yarn. It is then roved from yarn and placed onto bobbins where it is then spun onto

11 | P a g e

larger cones which will be sent all over to be processed into cotton material such as cloth diapers

(Cherret, Barrett, Clemett, Chadwick, & Chadwick, 2005).

Ecological Footprint of Cotton

In a 2005 report prepared by the BioRegional Development Group the cotton fiber production

ecological footprint was studied by breaking down the impact of the processes into two stages. This

report used twelve case studies that broke down the location, type of cultivation practice, and

manufacturing processed of organic cotton, cotton, hemp, and polyester (Cherret, Barrett, Clemett,

Chadwick, & Chadwick, 2005).

The first step was to analyze the agricultural processes of cotton. Cotton production seems to be

very efficient in yield of product versus how much land is used to cultivate, 2.5% of global agricultural

land is used to produce the 36% of the textile uses cotton is processed into (Cotton Counts,

2011).However, it was found that it takes up to 29,000 liters of water to grow a kilogram of cotton in

areas where there is insufficient rainfall. It was estimated that 73% of global cotton production is

harvested in irrigated areas (Cherret, Barrett, Clemett, Chadwick, & Chadwick, 2005).

The second step to analyze the footprint of cotton production was to calculate the impact of

manufacturing cotton from the ginning process to the manufacturing of fabric. The energy requirements

of fiber production for a tradition cotton factory in the United States requires over 35,000 mega joules

of energy per ton and emits 6.5 kilograms of CO2 per ton (Cherret, Barrett, Clemett, Chadwick, &

Chadwick, 2005). The results of this study showed that the ecological footprint represent in global

hectares per ton of spun fiber placed cotton production in the US at 2.5 gha/ton for crop cultivation and

almost 3 gha/ton for fiber production (Cherret, Barrett, Clemett, Chadwick, & Chadwick, 2005). This

essentially means that there is a greater land area required to produce cotton yields than alternative

materials (Appendix III).

12 | P a g e

Environmental Impacts of Cotton Cultivation

Most cotton crops use a process of flood irrigation which has several detrimental effects on the

environment such as eutrophication, salinisation, pollution, disruption of water tables, and habitat

destruction. A major environmental concern for the process of flood irrigation is the pollution generated

by the application of fertilizers, insecticides, herbicides, growth regulators, and other defoliants used to

manage cotton crops. The energy requirements for the cultivation of a cotton farm in the US requires a

little over 20,000 mega joules per ton and produces over 4 kilograms of CO2 per ton (Cherret, Barrett,

Clemett, Chadwick, & Chadwick, 2005).

Conclusion

The process of extracting resources for the production of the material used in the manufacture

of diapers requires a lot of time, money, energy, and resources. Since the invention of disposable

diapers in the 1940’s and the advancements made in the 90’s an astronomical amount of waste has

been generated. Many companies such as Kimberly Clark and Proctor and Gamble are trying to create

more sustainable line of disposable diapers by using more biodegradable materials as well as working

with other companies to reduce their environmental impact of their products used for disposables.

Every step a company makes will help lower the ecological footprint is a step in the right direction to

limit the amount of waste ending up in landfills.

13 | P a g e

Appendix I

Figure 1

http://www.madehow.com/Volume-3/Disposable-Diaper.html

14 | P a g e

Appendix II

Figure 2

Priscilla Lepoutre (Transpak Industries Ltd.)

15 | P a g e

Appendix III

16 | P a g e

Appendix III Continued

(Cherret, Barrett, Clemett, Chadwick, & Chadwick, 2005)

17 | P a g e

Works Cited

Balter, M. (2006). The Baby Deficit. Science , 1895.

Beil, S. C. (2004). The Diaper Dilemma: The Environmental Cost of Diapers. Retrieved February 2011, from Natural Mamas:

www.punkinbutt.com

Cherret, N., Barrett, J., Clemett, A., Chadwick, M., & Chadwick, M. (2005). Ecological Footprint and Water Analysis of Cotton,

Hemp and Polester. Stockholm: BioRegional Development Group and WWF Cymru.

Cline, C. (2011, Frebruary 11). Owner/Operator Nature Bumz Co. (M. Kroliczak, Interviewer)

Collins English Dictionary . (2011, February 28). Retrieved from Dictionary.com:

http://dictionary.reference.com/browse/consumerism

Cotton Counts. (2011). Cotton: From Field to Fabric. Retrieved February 2011, from Cotton Counts: www.cottoncounts.net

Environmental Protection Agency. (1990-2009). Inventory of US Greenhouse Gas Emissions and Sinks.

Gilbert, S. G. (2010, July). Diapers. Retrieved February 2011, from Toxipedia: http://toxipedia.org/display/toxipedia/Diapers

Graham, B. a. (1998). Modern Superabsorbent Polymer Technology. John Wiley and Sons .

How Products are Made. (2011). Disposable Diaper. Made How , Volume 3.

Kids Growth.com. (n.d.). Retrieved February 2011, from Diapers and your Baby's First Year:

http://www.kidsgrowth.com/resources/articledetail.cfm?id=431

Kyla Boyse, R. a. (2010, March). University of Michigan Health System. Retrieved February 1, 2011, from Toilet Traing: Your

Child: University of Michigan Health System: http://www.med.umich.edu/yourchild/topics/toilet.htm

Lepourte, P. The Manufacture of Polyethylene. Transpak Industries Ltd.

Mirasol, F. (2011). ICIS.com. Retrieved Feruary 28, 2011, from Acrylic Acid Production and Manufacturing Process:

http://www.icis.com/Articles/2011/02/21/9436099/US-chemical-profile-Acrylic-acid.html

18 | P a g e

Office of Pollution Prevention and Toxics. (1994). The chemical identity and physical/chemical properties of acrylic. The United

States Environmental Protection Agency.

Peppas, B. a. (1994). Superabsorbent Polymers. ACS Symposium Series .

Pham, N. T., & Brown, E. W. (2009). DIAPERS AND THE ENVIRONMENT. Wakefield, MA: N E A R T A.

The Diaper Jungle. (2011). Retrieved 2011, from Adventures in Cloth Diapering: http://www.diaperjungle.com/diaper-history-

timeline.html

Transportation, U. D., & Commerce, U. D. (2007). 2007 Commodity Flow Survey. Economic and Statistics Administration.

Unite States Environmental Protection Agency. (2011). Identification of Nonhazardous Secondary Materials That Are Solid

Waste. Washington, DC: Unite States Environmental Protection Agency.

US Census Bureau. (n.d.). Retrieved February 20, 2011, from US Census Bureau: http://www.census.gov/