ecological footprint of diapers
TRANSCRIPT
Ecological Footprint of Diapers
MaryKate Kroliczak
Environmental Issues Spring 2011
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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.
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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
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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.
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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).
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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
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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).
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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).
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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).
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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
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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).
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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.
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Appendix I
Figure 1
http://www.madehow.com/Volume-3/Disposable-Diaper.html
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Appendix II
Figure 2
Priscilla Lepoutre (Transpak Industries Ltd.)
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Appendix III
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Appendix III Continued
(Cherret, Barrett, Clemett, Chadwick, & Chadwick, 2005)
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