ESNano_Environmental impacts of reusable nanoscale silver-coated hospital gowns compared to single-use disposable gowns

Environmental
Science
Nano
PAPER
Cite this: Environ. Sci.: Nano, 2016,
3, 1124
Received 13th June 2016,
Accepted 15th August 2016
DOI: 10.1039/c6en00168h
rsc.li/es-nano
Environmental impacts of reusable nanoscale
silver-coated hospital gowns compared to single-
use, disposable gowns†
A. L. Hicks,*ab
R. B. Reed,cd
T. L. Theis,b
D. Hanigan,ce
H. Huling,c
T. Zaikova,f
J. E. Hutchisonfg
and J. Millerg
Nanoscale silver has been incorporated into a variety of products where its antimicrobial properties en-
hance their functionality. One particular application is hospital linens, potential vectors of disease transmis-
sion. There is an on-going debate as to whether it is more beneficial to use disposable versus reusable
hospital gowns in efforts to prevent nosocomial infections. This work models the life cycle impacts of
nanoscale silver (nAg)-enabled, reusable hospital gowns from a life cycle assessment perspective and then
compares the midpoint environmental impact data to the use of disposable hospital gowns. A key finding
of this work is the environmental parity (when the environmental impact of nAg and disposable gowns are
equal) of a nAg-enabled gown is 12 wearings. These results suggest that nAg textiles may be key in reduc-
ing the environmental impact of hospitals, while still preventing infection.
1.0 Introduction
The antimicrobial properties of nanoscale silver (nAg) are of
considerable interest from a consumer application
standpoint,1–3
resulting in a multitude of nAg-enabled prod-
ucts, including wearable textiles, bandages, water filters,
toothpaste, air purifiers, baby products, and food storage.4–9
For the purposes of this work, nanoscale will be defined as
materials where one or more of the dimensions are less than
100 nanometers (nm). The Woodrow Wilson Center's Project
on Emerging Nanomaterials (PEN)4
database lists 488 nAg-
enabled products. The “Health and Fitness” category con-
tains the greatest portion of these products, at 266. nAg en-
abled textiles are included in this category, suggesting that
there is the potential for significant adoption of these prod-
ucts. The global nAg market is expected to be worth $2415.5
million US dollars by 2023.10
North America, in particular,
accounted for more than 40% of the global demand for nAg
products in 2014.
Previous life cycle assessment (LCA) studies have found
the laundering phase to have the greatest environmental im-
pact during the lifetime of a garment,11,12
thus one of the
purported benefits of nAg enabled textiles includes less fre-
quent laundering, since antimicrobial effects persist over
time, potentially resulting in a reduction in the overall life-
time environmental impact. Meyer et al. used a screening-
level LCA to model the inclusion of nAg in socks.13
Walser
et al. compared nAg shirts with both conventional (shirts
without antimicrobial properties) and triclosan (a commonly
used chemical antimicrobial) treated shirts, and found
1124 | Environ. Sci.: Nano, 2016, 3, 1124–1132 This journal is © The Royal Society of Chemistry 2016
a
Department of Civil and Environmental Engineering, University of Wisconsin-
Madison, 2208 Engineering Hall, 1415 Engineering Drive, Madison, WI 53706,
USA. E-mail: hicks5@wisc.edu
b
Institute for Environmental Science and Policy, University of Illinois at Chicago,
2121 West Taylor, Chicago, IL, 60612, USA
c
School of Sustainable Engineering and The Built Environment, Arizona State
University, Tempe, AZ, 85287, USA
d
Department of Chemistry and Geochemistry, Colorado School of Mines, Golden,
CO, 80401, USA
e
Department of Civil and Environmental Engineering, University of Nevada, Reno,
NV, 89557, USA
f
Department of Chemistry and Biochemistry, University of Oregon, Eugene, OR,
97402, USA
g
Dune Sciences, Inc., 1900 Millrace Drive, Eugene, OR, 97403, USA
† Electronic supplementary information (ESI) available. See DOI: 10.1039/
c6en00168h
Nano impact
Nanoscale silver is the most common nanomaterial incorporated into consumer products, due to its antimicrobial nature. This antimicrobial benefit is
relevant with respect to textiles in medical settings, where there is a current debate as to the use of disposable versus reusable linens for disease
transmission prevention. In this study a life cycle assessment of a commercial nanosilver treatment is compared in the context of a hospital setting for use
in reusable gowns compared to disposable gowns. This study is valuable with respect to understanding the potential environmental advantages of the
application of nanosilver in a healthcare setting.

Environ. Sci.: Nano, 2016, 3, 1124–1132 | 1125This journal is © The Royal Society of Chemistry 2016
consumer actions during the use phase greatly influence the
results.14
Hicks et al.15
found that the portion of the life cycle
of the textile with the greatest impact depends largely on the
initial silver content, laundering behavior, and environmental
impact category considered. Additionally, Pourzahedi and
Eckelman conducted a LCA study of nAg bandages, finding
that the quantity of bulk silver used was the greatest contrib-
utor in terms of environmental impact to the process of nAg
synthesis (and thus not the reagents or heating
employed).5,16
The present work seeks to expand on previous
studies by investigating the environmental impacts of a new
nAg synthesis method, and a process to attach the nAg to tex-
tile surfaces. The textiles produced by this method are evalu-
ated, in comparison to disposable textiles, for their potential
to reduce disease transmission and environmental impact in
the health care field.
Although the majority of the nAg is commonly lost from a
fabric after relatively few launderings, there is the potential
for reapplication to the garment.15
Most nAg-enabled textiles
are sold with the silver already in place, with no potential to
replenish the lost silver.17,18
However, a nAg aftermarket solu-
tion (the nAg studied in this work), can be attached to textiles
using a commercial washer, the nAg solution, and a proprie-
tary linking agent. This application (and the possibility for
reapplication) would be particularly beneficial in a hospital
or long-term care facility setting, where there is the potential
for textiles to serve as vectors of pathogen transmission. This
is especially true for textiles that are not frequently laundered
such as curtains.
Hospital acquired infections are the 4th leading cause of
death in the United States (behind heart disease, cancer, and
stroke).19
Reducing transmission of infection and/or transfer
of contamination is imperative, and has clear applicability in
hospital and other sterile settings. In a hospital setting the
sources of potential contamination are numerous, and in-
clude the floor, bed linens, gowns, overbed tables, and blood
pressure cuffs.20
Methicillin-resistant Staphylococcus aureus
(MRSA) infections have been reported by the Centers for Dis-
ease Control (CDC), to spread through indirect contact, such
as touching contaminated objects (including sheets, towels,
wound dressings, and clothing) that have come into direct
contact with the infected wound.21
In one study, hospital
linens were evaluated for their role in microbial transfer,
clean linen (prior to patient contact), dirty linen, and staff
uniforms were all found to be contaminated with pathogenic
microbes.22
With hospital acquired infections in adults cost-
ing approximately $10 billion in the United States annually,
biocidal textiles (such as nAg-enabled) have been proposed as
an effective method for the reduction of hospital acquired
infections.23–25
Currently, there is significant debate as to whether dis-
posable or multiuse products are a better choice in medical
settings, such as hospitals with respect to disease
transmission.26–28
Previous LCA work by Overcash29
and
Ponder30
has identified the potential to significantly reduce
the environmental impact of hospital gowns by switching
to reusables. This case study is useful to illustrate the po-
tential benefits, under a well-defined usage scenario, of
nAg-enabled textiles when compared to their disposable
counterparts to inform the debate. Eighty percent of hospi-
tals in the United States employ single use (disposable)
hospital gowns and drapes.31,32
One surgical waste audit
found that 39% of the surgical waste was due to disposable
surgical linens, amounting to 10.2 kg per surgery.33
Approx-
imately 80% of hospitals in the United States utilize dispos-
able drapes and gowns.33
In the United States, in 2010,
there were 51.4 million in patient surgical procedures,34
suggesting a potential to produce 419.2 million kg of surgi-
cal waste due to disposable linens annually for only inpa-
tient surgical procedures. The use of reusable gowns and
drapes would significantly reduce that quantity of waste.
One concern in this debate is whether or not the multiuse
products will serve as reservoirs for pathogens, with the po-
tential to contribute to nosocomial infections.22
Biocidal
textiles, including nAg-enabled products, have the potential
to reduce the bacterial load stored in textiles, while poten-
tially reducing the environmental impact by moving to re-
usable products,30
in the hospital setting. Also, some hospi-
tals have transitioned to allowing medical staff to launder
items such as scrubs and uniforms at home.35
This raises
the possibility of introducing these pathogens into the
home environment, and the potential for ineffective laun-
dering due to home laundering equipment, although so far
that has not been shown to occur.35
This work will explore
the relative life cycle impacts of disposable versus multiuse
nAg-enabled hospital gowns produced using the nAg prod-
uct and attachment process developed by Dune Sciences.
Dune Sciences manufactures nanoscale products, such as
nAg coatings, and grids for different microscopy sample
preparations (such as functionalized grids for transmission
electron microscopy).36
A consequence of the adoption and use of nAg enabled
products is the introduction of nAg to the environment. As
stated previously there is significant variation in the quantity
of silver attached and thus lost during the lifetime of nAg tex-
tiles.15
Recent work by Gilbertson et al.37
characterized the
many challenges of deriving factors to characterize the toxic-
ity of nanomaterials (with nAg particularly discussed). Based
on sets of meta-analysis they concluded that for nAg when a
fixed percentage of ionic release is assumed (as is done in
this work) that there is the potential to overestimate the tox-
icity impacts of the nAg.37
The speciation of the silver enter-
ing the wastewater treatment plant is relevant from a toxicity
perspective. Although the presence of ionic silver in the en-
vironment due to release from nAg enabled textiles, repre-
sents a potentially negative impact to the environment,38,39
most studies have concluded that the silver will be in the
form of Ag2S,40–42
although secondary forms such as AgCl
(ref. 43) are also possible. In freshwater conditions, the antic-
ipated discharge location, Ag2S has not been found to be bio-
available, and due to this is not considered to be as toxic as
ionic silver.44
Environmental Science: Nano Paper

The impact of the silver discharged to the environment is
also a function of scale. Broad scale adoption of these nAg
textiles would introduce more silver into the environment,
and thus potentially amplifying its impact on the environ-
ment. nAg particles in the wastewater treatment system have
been found to inhibit nitrification at a concentration of 0.1
mg L−1
.40,45,46
Nitrification is the process of converting am-
monia to nitrite and nitrate in the wastewater system. Anaer-
obic digestion is a method for handling the biosolids pro-
duced in the wastewater treatment system, and produces
biogas during the digestion or composting process. A signifi-
cant difference in biogas production as a function of silver
concentration in the biosolids has not been observed with re-
spect to anaerobic digestion or composting,41,42,47
however a
reduction in landfill gas production has been observed as a
function of high silver levels.47
The nAg whose life cycle im-
pact is presented in this work has been characterized by Reed
et al.48
with respect to antimicrobial tests, zebra fish toxicity,
and utilizing electron microscopy.
At the same time there is an environmental impact of not
silver enabling the hospital gowns, and instead continuing to
use disposable gowns or utilizing a different biocidal agent.
Approximately 80% of surgical sheets and gowns utilized in
the United States are disposable.31,32
As previously men-
tioned, this contributes to the generation of surgical waste.
Walser et al.14
compared different methods of antimicrobially
enabling non-hospital textiles utilizing both silver and the
antimicrobial Triclosan. They found the environmental im-
pact of Triclosan application to be similar to that of a con-
ventional textile, while the environmental impact of utilizing
the nAg was largely dependent on the synthesis process, but
could be similar to that of a conventional textile. Beyond the
environmental impact of waste generation, a disposable gown
has an embodied energy of 3.01 MJ, while a reusable gown
has about 9 times that amount (27.3 MJ).30
If a lifetime of a
gown is considered to be 75 wearings,30
then the potential
for significant environmental savings from a raw materials
and manufacturing perspective is evident.
2.0 Methods
2.1 Goals
The potential environmental benefit of the nAg modelled in
this work is further evaluated by applying it to a case study of
hospital gowns. Hospital gowns present a potential applica-
tion for use of nAg for its antimicrobial properties, as hospi-
tal textiles have been identified as potential vectors of the
transmission of hospital acquired infections.26
This is largely
due to the issue that some pathogens have been found to re-
main on and in textiles even after laundering.49–55
Biocidal
finishes on textiles, along with the use of disposable textiles
are two methods that could be used to combat this, each with
a different environmental impact. In this work, reusable pa-
tient hospital gowns coated with the nAg product will be
compared with the use of disposable gowns from an environ-
mental impact perspective. Although this case study focuses
on a specific, well-defined usage scenario, the approach
should also be useful to evaluate the potential benefits of
nAg enabled textiles under other use scenarios.
2.2 Nanoparticle synthesis and attachment
The nAg is synthesized starting from silver nitrate, the most
common starting point for nAg synthesis.56
It is synthesized
according to a proprietary methodology utilized by Dune Sci-
ences, with a 60% yield.57
Due to a non-disclosure agree-
ment, the exact synthesis process may not be described in
this work. However, aggregate information may be found in
the supplemental material for this article hosted online. The
nAg is then attached to the polyester fabric with a proprietary
tethering method. The tethering process uses various chemi-
cal reagents along with heat and water in an industrial laun-
dering application, resulting in a concentration range of 20–
25 micrograms (μg) of nAg/gram (g) of textile. An electricity
mix relevant to the United States was utilized in that analysis.
2.3 Hospital gown assumptions
The values used for the raw materials, manufacturing, and
laundering of the hospital cotton–polyester blend gown were
obtained from Ponder,30
who utilized the environmental im-
pact category of cumulative energy demand (CED) in her
analysis.30
The reusable gown has a mass of 230 g, and an as-
sumed lifetime of 75 launderings. The concentration of nAg
initially applied to the reusable gown was taken to be 20 μg
g−1
. The raw materials and manufacturing data for the dis-
posable hospital gown was also obtained from Ponder.30
A
disposable gown is considered to be single use and have a
mass of 60 g, and is disposed of after a single wearing.
The data utilized for modeling the cumulative energy de-
mand (CED) impact category of hospital gowns were taken
largely from literature. Ponder30
found the impact of the raw
materials and manufacturing of a reusable gown to be 27.31
mega joules (MJ) per gown, and 3.01 per disposable gown.
The impact per gown per laundering was determined by Pon-
der30
to be 0.51 MJ, with the most significant contributions
due to washing, rinsing, and neutralizing (0.34 MJ), extrac-
tion (3.08 × 10−3
MJ), and drying (3.66 × 10−2
MJ). The dis-
posal data, in this instance modeled as landfill disposal, was
modeled utilizing the Sima Pro software, and a mass based
approach. The impact of synthesizing the nAg was completed
utilizing the LCA inventory data whose impacts are presented
in section 3.1, and applying the CED impact category.
2.4 Laundering procedure
Understanding the rate of silver loss from the textile is criti-
cal, as the nAg bestows the antimicrobial benefits on the tex-
tile. The nAg-enabled textiles studied in this work were found
to maintain their antimicrobial efficacy even after losses of
silver during, down to a concentration of 2 μg g−1
.48
In their
literature review, Hicks et al.15
found silver loss from fabrics
during laundering varies considerably. In order to obtain sil-
ver loss data on the particular nAg and attachment method
Environmental Science: NanoPaper

studied in this work, laundering experiments were
performed, as are detailed below.
The nAg-enabled textile (in this case entirely polyester)
samples were subjected to consecutive washings as a means
of assessing potential silver losses to the environment. The
textile samples were split into two groups: those washed in
nanopure water, and those washed in detergent. A standard
American Association of Textile Colorists and Chemists
(AATCC, 2003 formulation) laundry detergent was used in
half the wash samples to mimic conditions used for washing
in the home, as it was anticipated that the use of laundry de-
tergent would have the potential to influence the quantity of
silver lost during the laundering process. The concentration
of detergent was equivalent to 40 microliters (μL) concen-
trated detergent in 50 milliliters (mL) of nanopure water.
Triplicate fabric swatches (∼2 g each) were cut from each
shirt and placed in 250 mL polypropylene bottles with 50 mL
of water (with or without detergent) and 5 glass beads for agi-
tation. The bottles and beads were washed in 10% nitric acid
for at least 24 hours and rinsed at least three times with
nanopure water between textile washing experiments. The
bottles containing fabric swatches were secured in an end-
over-end mixer and rotated at 40 revolutions per minute
(rpm) for 30 minutes to provide agitation during washing.
The fabrics were removed from the bottles, and excess water
was allowed to drip from the fabrics before the fabrics were
transferred to aluminum foil drying dishes. The textiles were
then transferred to a drying oven and dried overnight at 50
°C, a temperature similar to household dryers. This was done
to remove any excess water from the fabric which might
cause extended release and dissolution of Ag particles on the
fibers over time. The tweezers were rinsed with nanopure wa-
ter between uses. For selected samples, aliquots of wash wa-
ter were taken after washing the textiles but before acidifica-
tion for ICP-MS analysis. These aliquots were filtered using a
30 kDa centrifugal ultrafilter for 30 minutes at 5000 g. The
remaining wash solutions were acidified to 2% HNO3 in the
250 mL bottles and analyzed by ICP-MS (Thermo X-Series II,
Waltham, MA).
2.5 Silver losses
The silver released during the laundering is assumed to enter
a wastewater treatment plant, and undergo standard treat-
ment conditions, where 95% will be removed into the bio-
mass.40
The silver contained in the biosolids is expected to
be in the form of Ag2S and AgCl, two relatively stable forms
of silver in the environment.40,42,43,47
The 5% of silver
discharged from the WWTP is modeled in the form of silver
ions (Ag+
) released to freshwater. Ionic silver is considered to
be more toxic in the aquatic environment, than its more sta-
ble counterparts.38,39,44
The toxicity of the Ag+
released from
the textile during laundering is characterized using the dis-
charge of Ag+
to freshwater systems allocation in SimaPro
(version 8.1). In this allocation, Ag+
loss contributes to the
non-carcinogenic and ecotoxicity impact categories, at a rate
of 2.45 × 10−3
CTUh and 1.34 × 106
CTUe per kilogram of
ionic silver discharged respectively.
2.6 End of life
Textiles in the United States are typically disposed of in a mu-
nicipal solid waste setting, which includes landfilling or in-
cineration.58,59
Based on the allocation of waste in other
healthcare studies, the disposal of the textiles will be
modeled in a landfill setting.60,61
2.7 Scope
Fig. 1 presents the overall scope of the LCA performed in this
work. This work analyzes the lifecycle impact of the synthesis
of nAg, its application to textiles in a hospital setting (initial
application and reapplication), and laundering of the textile.
An analysis of the use of disposable hospital gowns is also
presented for comparison. A major consideration in the cur-
rent healthcare debate with respect to reusable and dispos-
able textiles in a healthcare setting is the control of nosoco-
mial infections through the reduction of textiles as a vector
of pathogen transmission, as posited by Ponder.30
Two levels of scope are analyzed in this study. The first
level, nAg synthesis, which is denoted by the red box in
Fig. 2, analyzes the impact of synthesizing the nAg and
attaching it to the textile surface. These impacts are com-
pared to those of other nAg synthesis methods found in liter-
ature. The second level of scope, applying the nAg to the life
cycle of a hospital gown, is denoted by the blue. Where the
nAg synthesized previously is applied (and reapplied) to a re-
usable hospital gown, and the environmental impact is com-
pared to using disposable hospital gowns. This work addi-
tionally includes the environmental impact of the quantity of
silver lost along with the eventual end of life disposal of the
hospital gowns.
Fig. 1 The scope of LCA in this study, level 1 (within the red box)
represents the nAg synthesis, level 2 (within the blue box) represents
the large scale impacts of the hospital gown application. Italicized
inputs and outputs are included in the analysis.

2.8 LCA methodology
Sima Pro (version 8.1)62
was used to model the life cycle of
the nAg synthesis and attachment, with inventory values
obtained from both laboratory experimental data and the
Ecoinvent database (version 2.2). Mid-point environmental
impacts were evaluated using the U.S. Environmental Protec-
tion Agency's Tool for the Reduction and Assessment of
Chemicals and Other Environmental Impacts (TRACI).63
Nine
impact categories were evaluated in addition to cumulative
energy demand. The nAg synthesis and attachment data were
then put into context, exploring the environmental impact of
the use of nAg on hospital gowns. Multiple functional units
are employed to fully describe the system. The first func-
tional unit is per 4600 μg of nAg, the amount added to a hos-
pital gown and at each application. The second functional
unit is per one wear and laundering (where applicable) in or-
der to compared the reusable nAg enabled gown with the sin-
gle use gown, over a lifetime of 75 wearings.
3.0 Results and discussion
The LCA results presented are heavily informed by experi-
mental work, and thus in each portion of the life cycle the ex-
perimental work (if applicable) will be presented first, with
the life cycle modeling work presented second.
3.1 Silver synthesis results
The environmental impact of synthesizing the nAg particles
is presented in Fig. 2a. The source of the silver (in this case
silver nitrate) is the most significant contributor to the im-
pact of nAg synthesis, similar to the findings of Pourzahedi
and Eckelman.5
The attachment of the nAg to the textile (as
presented in Fig. 2b) includes the use of reagents, water, and
energy (at the laboratory scale). The reagent and energy usage
have the greatest environmental impacts. In all of the envi-
ronmental impact categories considered, the impact is
greater to attach the nAg to the textile than it is to synthesize
it. It should be noted, however, that these impacts are for a
laboratory scale attachment, and later in the work only the re-
agents necessary for attachment will be considered, as the at-
tachment will performed as part of a routine commercial
laundering procedure.
Comparing the process for nAg synthesis used by Dune
Sciences to those evaluated by Pourzahedi and Eckelman al-
lows for conclusions as to the relative environmental impact
to be drawn.16
These results are presented in Table 1.
In Table 1 the methods with the greatest and least envi-
ronmental impact in each impact category are highlighted,
using red and green respectively. The Dune nAg process had
the greatest environmental impact in three categories (acidifi-
cation, non carcinogenics, and respiratory effects), while FSP
dominated the remaining of the impact categories. Overall,
the RMS-AR-N method had the most number of “least” envi-
ronmental impacts. This suggests that the synthesis utilized
in this work is similar from an environmental impact stand-
point to that of other commonly used methods.
One important caveat in interpreting the data in Table 1 is
that the functional unit is strictly based upon the mass of
nAg. In fact, the nanoparticle size, size distribution, purity
and coating chemistries are all different for each synthesis
and the performance of the different nAg forms depend upon
those variables. Thus, direct comparisons of impacts would
require more detailed assessment of the performance of each
form of nAg as a textile coating. Nonetheless, it does provide
a baseline at which to compare impacts with respect to or-
ders of magnitude differences.
3.2 Potential silver losses to the environment
Fig. 3 presents results from nAg fabric laundering experi-
ments as cumulative silver washed from the fabric as a func-
tion of number of laundering cycles completed, as described
Fig. 2 Midpoint LCA results of portions of the lifecycle a) nAg
synthesis, b) attachment (per 1 hospital gown containing 4600 μg of
nAg).‡
‡ The units employed in each category are as follows: ozone depletion (kg CFC-
11 eq.), global warming (kg CO2 eq.), smog (kg O3 eq.), acidification (mol H+
eq.), eutrophication (kg N eq.), carcinogenics (CTUh), non carcinogenics (CTUh),
respiratory effects (kg PM10 eq.), and ecotoxicity (CTUe), with total values
displayed at the top of the chart for each category, per 4600 μg of nAg.

in the methods of laundering. In part A (Fig. 3), the silver
loss is presented for laundering in both DI water and with de-
tergent. Less silver is lost by the textile when it is laundered
utilizing the detergent. Part B presents the results of launder-
ing the textile until the majority of the silver was lost in DI
water, with the majority of the silver lost by the 11th launder-
ing cycle. The error bars on each figure are used to illustrate
variation among the laundering experiment results which
were done in triplicate. The results of Fig. 3 suggest that the
silver lost may be approximated using the first order rate law,
assuming an initial silver concentration on each textile of 20
μg g−1
. This gives a rate constant for the textile laundered in
detergent of 0.235 with time being defined as per laundering.
This would result in a concentration of silver below 2 μg
g−1
,48
the effective antimicrobial limit of the textile after the
17th laundering.
3.3 Environmental impact of hospital gowns
Ponder investigated the life cycle implications of both dispos-
able and reusable patient hospital gowns, utilizing a func-
tional unit of 75 000 gown wearings, composed of 1000 reus-
able gowns each laundered 74 times, or 75 000 disposable
gowns.30
The study found the lifetime energy consumption
for their functional unit for the reusable gown to be 65 049
mega joules (MJ) and 225, 947 MJ for the disposable gown.
These data suggest that using reusable gowns would result in
an energy savings of about 71% compared to the disposable
gowns. Given the observed loss of nAg in Fig. 3, the silver
could be reapplied at each set of 17 launderings. Fig. 4 pre-
sents a comparison of the environmental impact of using a
nAg-enabled gown (with reapplication of the nAg solution
and linking agent every 17 launderings) to the disposable
gown, utilizing energy consumption (cumulative energy de-
mand) as the impact category, for the sake of comparability,
as that was the sole impact category utilized by Ponder. From
an impact perspective, it is more energy intensive to attach
the nAg (2.73 MJ) than to synthesize the nAg itself (5.27 ×
Table 1 Environmental impact of nAg synthesis by route for 4600 μg of nAga
a
The abbreviations for the types of nAg synthesis are defined as CR-EG (silver nitrate and ethylene glycol), CR-SB (silver nitrate and sodium
borohydride), CR-TSC (silver nitrate and trisodium citrate), CR-STARCH (silver nitrate and potato starch), FSP (silver and flame spray pyrolysis),
RMS-AR-N (silver and reactive magnetron sputtering with argon and nitrogen gas), and AP (silver and arc plasma). More detail in regards to the
nAg synthesis using each method may be found in ref. 14. Per 4600 μg of nAg.
Fig. 3 Cumulative silver losses as a function of textile laundering a)
laundered DI water and detergent, b) laundered with DI water for an
extended number of launderings.

10−2
MJ), per textile per application. However, the attachment
is designed to be performed in an industrial laundering set-
ting, meaning that the silver and linking solution could be
added to every 17th laundering of the hospital gowns (at an
energy cost of 1.94 MJ per reapplication per gown – including
the nAg solution). Eqn (1) and (2) express the energy con-
sumption of each gown option as a function of number of
times that the gown has been worn.
DispImp = (3.01 MJ + 7.89 × 10−4
MJ) × (wear) (1)
ReuseImp = (27.3 MJ + 1.94 MJ) + (0.51 MJ × wear) (2)
The impact of the disposable gown (DispImp) is a func-
tion of the number of equivalent wearings, meaning that a
new gown (3.01 MJ) is used for each wearing. The impact of
the reusable gown (ReuseImp) is a function of the raw mate-
rials and manufacturing used to create the gown (27.31 MJ),
and 1.94 MJ is the initial silver synthesis and attachment and
the amount of energy used to launder the gown (0.51 MJ),
with the assumption that the gown is laundered prior to its
first wear in order to attach the silver. Additionally, at every
17th laundering 1.94 MJ will be added to the impact to ac-
count for the nAg applied during the laundering cycle. The
end of life disposal of the two hospital gown options will oc-
cur in a landfill setting, and will contribute to each dispos-
able gown (7.89 × 10−4
MJ) and once to the reusable gown af-
ter 75 wearings (1.16 × 10−2
MJ). These impacts are per gown,
and are based on the mass of each gown going to the
landfill.
Initially, using the disposable gown reduces the amount
of energy consumed in the system. However, at wear 12, the
reusable gown becomes the less energy intensive option. As-
suming a gown lifetime of 75 wears,30
this suggests that the
reusable gown may be a better choice from an energy con-
sumption standpoint. Although the impact of the reusable
gown appears to be linear over time, small stepwise increases
are seen every 17 launderings due to the reapplication of the
nAg. Also, the silver loss is non-linear over time, however,
that uncertainty is not incorporated into Fig. 4, as the nAg
emitted in ionic form to freshwater does not contribute to
the CED. The nAg modeled in this work has been tested with
respect to antimicrobial efficacy, and has been found to pro-
vide inhibition at concentrations as low as 2 μg Ag g−1
fabric.48
3.4 Uncertainty and sensitivity
As with most LCA work, uncertainty exists within this work.
In order to quantify the potential influence of the inputs and
assumptions utilized on the impacts quantified, scenarios
are posited such as changes in yield of the nAg produced, re-
agent, water, and energy consumption. In each instance,
presented in Fig. 5, the initial value utilized in the analysis
has been increased and decreased by 50%.
The sensitivity of the impacts to a 50% change in the in-
ventory is presented in Fig. 5, a percentage change of each
impact category. The inventory item with the most influence
is the amount of silver utilized to produce the nAg. This sug-
gests that increasing the yield of the process would notice-
ably decrease the corresponding environmental impact of
synthesizing the nAg. The smallest percentage of change was
seen for the water and electricity consumption categories,
suggesting that the environmental impacts are least sensitiv-
ity to these inputs.
Uncertainty exists with respect as to the acceptable silver
concentration remaining on the textile for the healthcare fa-
cility. How often the nAg is reapplied will shift the environ-
mental impact of the reusable gown, and thus how many
launderings it would take for the reusable gown to be less en-
ergy intensive than its disposable counterpart. Fig. 6 presents
these points of parity with respect to frequency of nAg
application.
The frequency of the nAg reapplication to the reusable
gown influences the lifetime environmental impact of the
gown, and thus when parity with the disposable option will
be achieved. When the nAg is reapplied to the gown during
every laundering cycle, it will require 28 wears for the reus-
able gown to have a lower environmental impact than the
disposable gown. Although this is more than double the
Fig. 5 Sensitivity of impacts to inventory inputs (OZ – ozone depletion,
GW – global warming, SM – smog, AC – acidification, EU – eutrophication,
CN – carcinogenics, NC – non carcinogenics, RE – respiratory effects, EC –
eco toxicity). Percent change of impacts if expressed in decimal format.
Fig. 4 Lifetime energy consumption for reusable vs. disposable
hospital gowns with nAg.

number of wears required for parity at the rate of application
of every 17 wears, parity is still possible within the functional
lifetime of the gown. At a reapplication frequency of both 5
and 10 wearings, parity would be at 13 launderings, which is
not very different from the 12 launderings achieved with
reapplication after every 17 wearings. And finally, with
reapplication every 15 or 20 wearings, parity with the dispos-
able gowns would remain at 12 wearings. This uncertainty
analysis suggests that although more frequency application
of the nAg to the textiles would require more resources and
thus have a greater environmental impact, that there is still
potential within the 75 wearings lifetime of the reusable
gown for the reusable gown to have a lesser environmental
impact than the disposable option.
3.5 Limitations
This work explores the environmental impact of a method for
synthesizing and attaching nAg which may be completed in a
commercial laundering setting. This process is explored with
respect to hospital textiles, and gowns in particular, as a case
study where an antimicrobial textile would be potentially ben-
eficial, and nAg reapplication could occur. This study has
limitations, however, in particular only one synthesis and at-
tachment process for nAg was analyzed. Also, the environ-
mental impact of excess silver during synthesis and the silver
lost to the biosolids is not explored in this work. Additionally,
the comparison of reusable and disposable gowns relies on
prior work by Ponder,30
and utilizes only a single impact
category.
4.0 Conclusions
A commercially available synthesis and attachment process
for nAg-enabled textiles was evaluated utilizing a midpoint
LCA. Using nine impact categories, the environmental impact
of the synthesis for the nAg produced by this method was
found to be similar to that of other nAg synthesis processes.
The nAg was bound to the textiles using a chemical
crosslinking agent. Although the attached nAg was nearly all
lost from the textile by the 17th laundering, a novel aspect of
this nAg process is that it may be reapplied in an industrial
laundering setting. The application of such a process was in-
vestigated in the context of patient hospital gowns, a known
vector for disease transmission. Previous work has shown
this nAg system to provide microbial inhibition, even at fairly
low concentrations.49
When the nAg enabled textile was com-
pared to disposable hospital gowns, the energy consumption
was found to be much less during the lifetime of the reusable
hospital gown than continuously using disposable garments.
This suggests that nAg-enabling of reusable hospital gowns
may be a method for simultaneously lowering the environ-
mental impact and maintaining the antimicrobial perfor-
mance needed to combat textile vector pathogen transmis-
sion. The type of analysis used in this study should prove
useful in evaluating the potential for a net environmental
benefit for nano-enabled consumer products over a variety of
usage scenarios.
Acknowledgements
The authors acknowledge the generous support of the U.S. Envi-
ronmental Protection Agency Assistance Agreement No.
RD83558001-0 that funded this research. This work has not
been formally reviewed by EPA. The views expressed in this doc-
ument are solely those of the authors and do not necessarily re-
flect those of the Agency. EPA does not endorse any products or
commercial services mentioned in this publication.
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