Environmental impacts of examination gloves made of natural rubber and nitrile rubber, identified by life‐cycle assessment

Abstract

Medical examination gloves made of natural rubber (NR; powdered and non‐powdered) and synthetic nitrile rubber (NBR) were compared in terms of their environmental impact using life cycle assessments spanning material extraction, transportation to the glove production factory, the production process, and disposal by total incineration. ReCiPe Midpoint (H) V1.13/World Recipe H life cycle assessment method implemented using the SimaPro 9.0.0.48, was used. Single scores of each glove type and stage were determined by using weighting factors specifically obtained from a 2014 survey in Thailand. With current technologies, the overall environmental impact, or the total single score, of NR gloves was higher than of NBR gloves, because the glove production stage of NR gloves required more energy and sulfur use. In addition, the overall environmental impact of both types of gloves was found to be lower if powder coating was used rather than chlorination to reduce stickiness, and if glove production relied on natural gas for energy rather than coal. The single score approach revealed the hotspots for potential improvements for each glove type.

Full text

RESEARCH ARTICLE
Environmental impacts of examination gloves made of
natural rubber and nitrile rubber, identified by life-cycle
assessment
Supatra Patrawoot
1,2
| Thierry Tran
3,4
| Marisa Arunchaiya
5
|
Voranuch Somsongkul
6
| Yusuf Chisti
7
| Nanthiya Hansupalak
1,2,8,9
1
Department of Chemical Engineering, Kasetsart University, Bangkok, Thailand
2
Center of Excellence on Petrochemical and Materials Technology, Kasetsart University, Bangkok, Thailand
3
Qualisud/ELSA Group, Université Montpellier, CIRAD, Institut Agro, Université d'Avignon, Université de La Réunion, Montpellier, France
4
Alliance of Biodiversity International and the International Center for Tropical Agriculture (CIAT), Cali, Colombia
5
Department of Materials Science, Kasetsart University, Bangkok, Thailand
6
Department of Industrial Chemistry, King Mongkut's University of Technology North Bangkok, Bangkok, Thailand
7
School of Engineering, Massey University, Palmerston North, New Zealand
8
Center for Advanced Studies in Industrial Technology, Kasetsart University, Bangkok, Thailand
9
Specialized Center of Rubber and Polymer Materials for Agriculture and Industry, Kasetsart University, Bangkok, Thailand
Correspondence
Nanthiya Hansupalak, Department of
Chemical Engineering, Kasetsart
University, Bangkok 10900, Thailand.
Email: fengnyh@ku.ac.th
Funding information
National Research Council of Thailand;
Thailand Research Fund, Grant/Award
Number: RDG5850025
Abstract
Medical examination gloves made of natural rubber (NR; powdered and non-
powdered) and synthetic nitrile rubber (NBR) were compared in terms of their
environmental impact using life cycle assessments spanning material extraction,
transportation to the glove production factory, the production process, and dis-
posal by total incineration. ReCiPe Midpoint (H) V1.13/World Recipe H life
cycle assessment method implemented using the SimaPro 9.0.0.48, was used.
Single scores of each glove type and stage were determined by using weighting
factors specifically obtained from a 2014 survey in Thailand. With current tech-
nologies, the overall environmental impact, or the total single score, of NR
gloves was higher than of NBR gloves, because the glove production stage of NR
gloves required more energy and sulfur use. In addition, the overall environmen-
tal impact of both types of gloves was found to be lower if powder coating was
used rather than chlorination to reduce stickiness, and if glove production relied
on natural gas for energy rather than coal. The single score approach revealed
the hotspots for potential improvements for each glove type.
KEYWORDS
glove life-cycle-analysis (LCA), glove production, latex gloves, medical gloves
Received: 14 December 2020 Revised: 10 February 2021 Accepted: 13 February 2021
DOI: 10.1002/pls2.10036
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided
the original work is properly cited.
© 2021 The Authors. SPE Polymers published by Wiley Periodicals LLC. on behalf of Society of Plastics Engineers.
SPE Polymers. 2021;2:179–190. wileyonlinelibrary.com/journal/pls2 179

1|INTRODUCTION
Examination gloves are widely used in healthcare facili-
ties, laboratories, food factories, and diverse other busi-
nesses. Such gloves are designed for single use and
disposal to prevent transmission of infection. The global
demand for these gloves was around US$6 billion in 2019
and is expected to grow at a compounded annual rate of
10.6%–11.2% until 2027 at least. The largest markets for
examination gloves are North America and Europe.
[1,2]
The examination gloves used worldwide are produced
from either natural rubber (NR) or synthetic rubber
(e.g., nitrile, vinyl, and neoprene rubbers). NR is the
dominant material for producing gloves, followed by
nitrile rubber. These two materials are forecast to domi-
nate the global market for the foreseeable future.
[1]
Irrespective of the type of rubber used in their pro-
duction, examination gloves are available with and with-
out an internal powder coating of cornstarch. Powder
acts as a lubricant making coated gloves easier to put on
and remove. The powder also absorbs sweat, providing a
comfortable feel to the user,
[3]
although the use of pow-
dered gloves in medical facilities has been banned in sev-
eral countries (e.g., USA, Germany, Philippines, Japan,
and Saudi Arabia) because of concerns relating to con-
tamination and allergenic reactions in patients. This has
increased the demand for powder-free gloves. The
powder-free gloves are produced by two different
methods, either chlorination or polymer coating.
[4]
The
chlorination process usually involves multiple washings
of the powdered gloves with a solution of hypochlorite
and hydrochloric acid. During washing, the surface of the
rubber film is oxidized, decreasing friction, or tackiness
of the surface. In the alternative polymer coating method
of reducing surface stickiness, a polymer (e.g., acrylic
polyurethane, and silicone polymers) is used to coat
inner surface of the gloves,
[3,4]
and this may be followed
by chlorination.
Although NR examination gloves presently dominate
the global market and are expected to retain this domi-
nance at least in the near term,
[1]
the use of nitrile gloves
is growing rapidly. This preference for nitrile gloves is
driven by the presence of potentially allergenic proteins
on the surface of NR gloves.
[5,6]
These proteins occur nat-
urally in the latex harvested from the rubber tree and can
be removed with additional processing.
[5,6]
Allergenicity
notwithstanding, NR gloves have superior barrier prop-
erty, elasticity, resistance to sharp objects, and strength
than nitrile gloves
[4,7]
and are preferred in many
applications.
In addition to performance and price, the consumer
preference is increasingly influenced also by the environ-
mental impact of a product. Consequently, environmental
impacts are being assessed and used in product market-
ing. Environmental impact of a product can be calcu-
lated using a cradle-to-grave life cycle assessment (LCA).
LCA is an environmental management tool that
evaluates inputs, outputs, and potential environmental
impacts associated with a product during its entire life
cycle.
[8,9]
Although separate LCA of NR gloves and nitrile
gloves have been used to assess their environmental
impacts,
[10,11]
the specific types (e.g., medical examina-
tion, food processing, or industrial grade) of gloves used
in these evaluations were not specified.
[10,11]
LCA is
affected by the glove type because, depending on
intended application, their production requires different
amounts of raw materials (e.g., rubber and other
chemicals) and energy. Furthermore, earlier LCAs used
dissimilar functional units and focused on different envi-
ronmental impacts. Consequently, the environmental
performance of NR and nitrile gloves cannot be quantita-
tively compared based on the available reports.
[10,11]
The
present study fills this gap.
The present work assesses midpoint environmental
impacts of NR examination gloves (powdered and
powder-free) and powder-free nitrile examination gloves
using a LCA spanning the extraction of the raw materials
and energy, the production process, and disposal of the
used gloves. The actual use stage of the glove was
excluded from LCA as there were no inputs or emissions
associated with it. ReCiPe Midpoint (H) V1.13/World
Recipe H method and the SimaPro 9.0.0.48 software were
used for the characterization and normalization steps. To
provide multiple criteria for decision-making, all mid-
point environmental impacts were aggregated into a sin-
gle score by using weighting factors established by a
survey conducted in Thailand in 2014.
[12]
Process-related
data were collected on-site from two glove manufacturers
in Thailand. The data obtained enabled a robust compari-
son of the environmental impacts of NR and nitrile
examination gloves and of powdered and powder-free NR
gloves. Medical examination gloves referred to simply as
‘gloves’in the remainder of this work, were the specific
focus of this study. Hotspots of environmental impact
were identified and options were explored for reducing
these impacts.
2|MATERIALS AND METHODS
2.1 |The methodological approach
LCA comprised of the following four phases: Goal and
scope definition, the life cycle inventory (LCI) analysis,
environmental impact assessment, and interpretation.
[8,13]
180 PATRAWOOT ET AL.

The environmental impacts calculations were conducted
using the ReCiPe Midpoint (H) V1.13/World Recipe H
methods and SimaPro 9.0.0.48 software (www.
simapro.com).
2.2 |Goal, scope and system boundaries
The goals of the study were to evaluate cradle-to-grave
environmental impacts of: (1) Four glove types produced
at two factories; and (2) switching from coal to natural gas
in production of NR and nitrile gloves. The glove types
evaluated were: (1) Powder-free nitrile gloves produced at
Factory 1 (NBR_PF1); (2) powder-free NR gloves produced
at Factory 1 (NR_PF1); (3) powder coated NR gloves pro-
duced at Factory 2 (NR_PP2); and powder-free NR gloves
produced at Factory 2 (NR_PF2). The powder coating
material was corn starch in all cases. For comparison of
different products, all data were normalized to a common
basis of a functional unit (FU) of 100 pieces of gloves.
The relevant processes and systems boundaries are
shown in Figure 1. The production technologies and
processes for NR gloves at the two factories were differ-
ent, as summarized in Figure 1 (see caption). Route
1 (marked on the flow diagram in the orange box;
Figure 1) was the production path of NR_PF1 and
NBR_PF1 at Factory 1, whereas at Factory 2, Routes
2 and 3 applied to NR_PP2 and NR_PF2, respectively.
The system boundaries of all four glove types included
the transportation of materials to a glove factory, glove
production, and disposal (Figure 1). For production of
raw materials, two cases were considered: (1) For nitrile
gloves, the system boundaries included production of raw
materials (acrylonitrile butadiene rubber latex, or nitrile
latex for short), based on Ecoinvent LCI of acrylonitrile,
butadiene, and styrene
[14]
; and (2) for NR gloves, the sys-
tem boundaries included the agricultural production of
fresh NR latex (dry rubber content, or DRC, of 30%) and
production of concentrated NR latex with 60% DRC
(Figure 1).
Furthermore, after vulcanizing and cooling steps, the
production routes for NR_PF1, NR_PF2, and NR_PP2
were different as shown by the numbered arrows in
Figure 1 (orange box). NR_PF1 underwent the polymer
FIGURE 1 The common system boundaries for all four gloves comprised the glove production and disposal processes. For natural
rubber (NR) gloves, the system boundaries for agricultural production of NR latex and production of concentrated NR latex were added.
Route 1 (marked on flow diagram in the orange box) was the production path of powder-free NR gloves from Factory 1 (NR_PF1) and
powder-free nitrile gloves from Factory 1 (NBR_PF1), whereas Routes 2 and 3 were of powder coated NR gloves from Factory 2 (NR_PP2)
and powder-free NR gloves from Factory 2 (NR_PF2), respectively. Dashed lines specify boundaries for rubber plantation, concentrated NR
latex factory, glove factory, and the used glove disposal operation
PATRAWOOT ET AL.181

coating and chlorination treatments before drying, strip-
ping, inspection, and packaging (Route 1, Figure 1),
whereas NR_PP2 and NR_PF2 underwent powder dip-
ping together (Route 2, Figure 1). However, after being
stripped from the forming molds (or formers; Figure 1),
only NR_PP2 went straight for inspection and packaging,
whereas NR_PF2 went to chlorination treatment (Route
3, Figure 1). Finally, the production route for NBR_PF1
was nearly identical to that of NR_PF1, except that the
gloves underwent chlorination only, without polymer
coating.
The disposal stage took into account only the waste
gloves (excluding packaging boxes because they could be
recycled). Disposal was by incineration, a common prac-
tice for used medical gloves.
[11]
The impacts of infrastruc-
tures (factory buildings, machinery) were not included in
this analysis as their contributions were deemed insignifi-
cant in relation to the materials and energy consumed
during the 20–25 years lifetime of a factory.
2.3 |Life cycle inventory
Inputs and outputs for each system boundary were calcu-
lated for 1-year of production of gloves and were then
normalized to a FU of 100 pieces of gloves. The input–
output data for glove production were collected via onsite
interviews with staff of the two factories. LCI of the four
glove types were proprietary and protected by confidenti-
ality agreements with the two factories involved, but life
cycle inventories for similar products have been reported
elsewhere.
[10,11]
The input–output data for agricultural production of
fresh NR latex and production of concentrated NR latex
were retrieved from Thai National Life Cycle Inventory
Database.
[15]
The LCI of production and concentration of
fresh NR latex are confidential, but LCI data for similar
products are available in the literature.
[11]
LCI of acrylonitrile butadiene rubber latex, or nitrile
latex, was not available in Thai National Life Cycle
Inventory Database,
[15]
but the major components of
nitrile latex (i.e., acrylonitrile and butadiene) are similar
to those of ABS (acrylonitrile butadiene styrene) plastic.
Therefore, the LCI of nitrile rubber was estimated by
excluding styrene from the LCI of ABS retrieved from
Thai National Life Cycle Inventory Database.
[15]
Generic data (e.g., transportation vehicles, chemicals)
were retrieved from Ecoinvent (www.ecoinvent.org). All
chemicals and packaging used in the glove production,
except latexes, were assumed to be transported from cen-
tral Bangkok to each glove factory. Both NR and nitrile
rubber latexes came from provinces located near the two
factories.
Factory 1 produced powder-free NR gloves and
powder-free nitrile gloves by using the same production
lines, but at different times. Similarly, Factory 2 produced
powder-free NR gloves and powdered NR gloves by using
the same production lines, but at different times. The
data on water and energy (electricity and fuel) use of
each factory were based on the monthly bills for the year
of data collection. As the factories did not record water
and energy use separately for each type of glove, these
data were estimated for each factory based on its total
consumption and the quantities (number of pieces) of
each glove type it produced in the year of LCI collection.
The process wastewater in each factory was screened
to remove rubber scrap and then released into an open
biological treatment lagoon. The treatment involved
anaerobic fermentation of the organic matter and released
methane and carbon dioxide gases into the atmosphere.
The treated water from Factory 1 was fed to a water
spraying system to improve dust control in the coal work-
ing area. During spraying, some water evaporated and
some percolated into the ground. The quantity of water
seeping into the ground and any pollutants it may have
leached from the coal dust into the soil, could not be
evaluated reliably. In addition to the water seeping into
the earth, water also left the system boundary as vapor
during drying processes and other activities in the fac-
tory. As the compositions in the water leaving the system
boundary were not known, the water discharge data cell
in SimaPro was left blank, implying no environmental
contribution from the water discharged.
After treatment, the water discharged from Factory
2 had a chemical oxygen demand within the regulatory
norms for such factories in Thailand, and was released to
a natural water source outside the factory boundary.
There was no metered record of water discharge and
therefore it was taken to be 50% of the water entering the
factory perimeter. Thus, the remaining 50% of the input
water left the boundary as vapor from drying processes,
as was the case in Factory 1.
The solid waste in both factories was the gloves that
failed quality tests and rubber scrap retrieved from the
wastewater. The solid waste was sold to a third party who
burnt it to recuperate heat for other processes. Thus, the
total environmental impact of the glove production had
to be divided, or allocated, to the gloves passing the qual-
ity tests and those in the solid waste. The allocation of
environmental impacts between the product and the
waste was performed on a mass basis. The mass of waste
gloves in each factory was approximated to be 3% of the
total mass of gloves produced per year. Thus, the gloves
passing the quality tests were assigned 97% of the total
environmental impact and the waste gloves were
assigned 3% of the total environmental impact.
182 PATRAWOOT ET AL.

Emissions to air from the glove factories were mainly
a consequence of the fuel burnt. Factory 1 burnt coal
while Factory 2 used natural gas. In addition, there were
emissions (CH
4
and CO
2
) from open wastewater treat-
ment lagoons at both factories.
Waste gloves in this study were treated as infectious
waste. Such waste can be disposed by incineration, or
other methods.
[16]
The ash produced is handled as if it
were municipal solid waste.
[16]
For disposal of infectious
waste by methods other than incineration, additional
tests are required to demonstrate destruction of patho-
gens. Hence, in Thailand waste medical gloves are mostly
disposed by incineration.
[11]
In a typical incinerator,
[17]
the waste is burnt in two
consecutive stages. In the first stage, the waste is pyro-
lyzed at 760–980C under oxygen-limiting conditions.
This dries the waste and decompose it to volatile gases
and ash. The volatile gases formed in the first stage are
burnt in the second stage at 980–1095C with excess air
to achieve complete combustion. The ash produced is dis-
posed in landfills like most municipal solid waste.
[16]
For this study, incineration was assumed to result in
complete combustion of waste gloves. Elemental analysis
(CHNS/O analyzer; Thermo Scientific™FLASH 2000),
thermogravimetric analysis (TGA/DSC1; Mettler Toledo)
and scanning electron microscopy (Quanta 450 SEM with
Energy Dispersive X-Ray Analysis; FEI) were used to
determine the compositions of all four glove types under
study. Based on the experimentally determined elemental
compositions, the assumption of complete combustion
and stoichiometric considerations,
[18]
emissions to atmo-
sphere and the ash production were estimated. Ash is
potentially recyclable and recycling reduces its environ-
mental impact.
[19]
Therefore, any environmental impact of
disposing ash from glove incineration, was disregarded. In
addition, environmental contributions of the fuel used in
starting up the incinerator were neglected because com-
bustion of rubber gloves is self-sustaining, that is, little or
no fuel is required once combustion begins.
2.4 |Impact assessment
The LCI of all activities for a FU of 100 pieces of gloves
produced in any factory was converted to 18 environmen-
tal impact indicators based on ReCiPe Midpoint
(H) V1.13/World Recipe H (Table 1). This LCI included
contributions from the rubber plantation, production of
the concentrated NR latex (Figure 1) and final disposal of
the used gloves.
To assist decision makers and other users of environ-
mental impact studies, all 18 environmental impact indi-
cators (Table 1) were normalized and combined into a
single score based on weighting factors. Normalization of
the environmental impacts involved the calculation of
the magnitude of a category indicator relative to some
reference information (e.g., the average yearly emission,
or consumption by one individual in a reference area).
The value of each impact indicator was divided by a
corresponding normalization factor to generate a dimen-
sionless number for each of the 18 environmental impact
categories. The resulting set of dimensionless values was
then multiplied by a set of weighting factors. The
weighting factors prioritized impact categories from those
of highest concern to those of lowest concern, as per-
ceived by the people in the geographic region of focus.
Finally, all 18 weighted dimensionless impact values
were aggregated into a single score for a product or a ser-
vice.
[20,21]
The following equation was used in calculating
the single score (point, Pt) of a system boundary:
Single score PtðÞ=W1
V1
F1

+W2
V2
F2

++W18
V18
F18

,
ð1Þ
TABLE 1 Environmental impact indicators, the corresponding
acronyms and units
Impact category Acronym Units
Climate change CC kg CO
2
eq
Ozone depletion OD kg CFC-11
eq
Terrestrial acidification TA kg SO
2
eq
Freshwater eutrophication FE kg P eq
Marine eutrophication ME kg N eq
Human toxicity HT kg 1,4-DB eq
Photochemical oxidant
formation
POF kg NMVOC
Particulate matter formation PMF kg PM
10
eq
Terrestrial ecotoxicity TET kg 1,4-DB eq
Freshwater ecotoxicity FET kg 1,4-DB eq
Marine ecotoxicity MET kg 1,4-DB eq
Ionizing radiation IR kBq U
235
eq
Agricultural land occupation ALO m
2
a
Urban land occupation ULO m
2
a
Natural land transformation NLT m
2
Water depletion WD m
3
Metal depletion MRD kg Fe eq
Fossil depletion FD kg oil eq
Note: Based on ReCiPe Midpoint (H) V1.13/World Recipe H.
Abbreviations: CFC, chlorofluorocarbons; 1,4-DB, 1,4-dichlorobenzene;
NMVCO, non-methane volatile organic compounds; PM
10
, particulate
matter with diameter < 10 μm.
PATRAWOOT ET AL.183

where V
i
was the total value of the environmental impact
category icontributed by all activities in a system bound-
ary, F
i
was the normalization factor for the impact cate-
gory i, and W
i
was the weighting factor associated with
the impact category i.
In the present work, all computations of environmen-
tal impact category values and normalization were car-
ried out using the SimaPro 9.0.0.48 with ReCiPe
Midpoint (H) V1.13/World Recipe H. Single scores were
determined manually. The weighting factors were from a
2014 survey of the environmental concerns and priorities
of the respondents.
[12]
3|RESULTS AND DISCUSSION
3.1 |Characterization results
A common observation for all four glove types was that
the glove production stage contributed the most (>50%)
to the impact categories CC, OD, FE, ME, HT, POF, TET,
FET, MET, IR, ALO, ULO, NLT, WD, MRD, and FD for
1 FU of gloves produced (Figures 2(A)–(D)). Further
investigation revealed (Figure 3) that for most of these
environmental impact categories, fuel production and
use contributed the most (>50%) to the glove types
NR_PF1 and NBR_PF1. Fuel production and use contrib-
uted the most (>50%) also to the glove types NR_PF2 and
NR_PP2, but in fewer impact categories compared to the
glove types NR_PF1 and NBR_PF1. This could be
ascertained simply by counting the number of impact cat-
egories in Figures 3(A)–(D) for the different glove types.
These results implied that coal production and burning
contributed a greater environmental impact compared
with the use of natural gas as fuel. As a consequence,
when natural gas was used, the environmental impact
contributions of the other activities were made apparent
through magnification in relative terms. Fuel, or heating
requirements, has been found to contribute the most to
environmental impacts also in other studies of glove pro-
duction.
[10]
In glove production processes, coal and gas
are used to mainly generate heat for warming liquid
latexes, drying and chlorination.
Production of concentrated latex (i.e., NR and nitrile
latexes) and transportation of materials to the glove fac-
tory also contributed to environmental burdens, but their
FIGURE 2 The total characterization results for production of one functional unit (FU) of gloves, shown as percentage contribution.
“Concentrated latex”means natural rubber (NR) concentrated latex used in making NR gloves (Figures 2(A), (C), (D)), and nitrile latex used
in making nitrile gloves (Figure 2(B)). See Table 1 for explanation of the acronyms shown below the bars. Glove types: Powder-free NR
gloves from Factory 1 (NR_PF1); powder-free nitrile gloves from Factory 1 (NBR_PF1); powder-free NR gloves from Factory 2 (NR_PF2);
powder coated NR gloves from Factory 2 (NR_PP2)
184 PATRAWOOT ET AL.

impact was relatively small in the glove production stage
(Figures 2(A)–(D)). The environmental impacts of pro-
duction of concentrated NR latex in Figures 2(A), (C),
and (D) were assessed using a gate-to-gate approach.
Thus, these impacts included both activities inside and
outside the factory. The activities outside the factory
(i.e., outside the latex production stage) were those relat-
ing to production of chemicals, water, and energy (fuel
and electricity), but excluding the activities involved in
the production of fresh NR latex. The environmental
impacts of the production of fresh NR latex were sepa-
rately determined using a cradle-to-gate approach,
accounting for all activities involved outside the planta-
tion boundary relating to all materials, water, and energy
that entered the plantation, as well as all activities occur-
ring within the plantation. In contrast to the gate-to-gate
approach used for assessing impacts of production of
concentrated NR latex, the impacts of production of
nitrile latex were determined using a cradle-to-gate
approach. This took into account all activities relating to
materials, water, and energy that went into the latex pro-
duction stage and all activities occurring within the latex
production stage.
A comparison of all 18 impact categories for the four
glove types (Figure 4) revealed that NR_PP2 contributed
the least to nearly all environmental impact categories
except OD, that is, the emissions related to depletion of
ozone.
3.2 |Single score results
Different individual impact categories often have differ-
ent units (Table 1) and therefore cannot be compared. To
FIGURE 3 The total characterization results, classified by activities within the glove factories per 1 FU of gloves, shown as percentage
contribution. To enable comparison with nitrile rubber (NBR), the environmental impacts for both latexes were evaluated by using a cradle-
to-gate approach. Thus, the environmental impacts of production of the concentrated natural rubber (NR) latex were the sum of the impacts
from the production of fresh NR latex and those of concentrated NR latex. “Concentrated latex”means NR concentrated latex (includes
production of fresh NR latex) for NR gloves (Figures 3(A), (C), (D)), and nitrile latex for nitrile gloves (Figure 3(B)). See Table 1 for
explanation of the acronyms shown below the bars. See caption of Figure 2 for explanation of glove types
PATRAWOOT ET AL.185

simplify comparison of overall impact, the impact cate-
gory results from the previous section were aggregated
into a single score. This score represented the overall
environmental impact of a glove type as perceived by the
survey respondents. This single-score approach allowed
easy identification of the glove type with the least overall
environmental impact and recognition of production
stages with high overall impacts.
The glove type NR_PF1 was found to have the highest
weighted contribution to the overall environmental
impacts, followed by NBR_PF1, NR_PF2, and NR_PP2,
respectively (Figure 5(A)). For all glove types, the glove
production stage had the highest contribution to the
overall environmental impacts (>50%) (Figure 5(A)). This
dominant impact of the production stage for glove types
NR_PF1, NBR_PF1 and NR_PF2 was linked to their fuel
use (production and consumption of fuel; see table in
Figure 5(B)). In contrast, the high impact of the produc-
tion stage of glove type NR_PP2 was linked to the
chemicals used (see table in Figure 5(B)).
3.3 |Effect of substituting coal for
natural gas in Factory 1 on the overall
environmental impact
This study of fuel substitution was conducted to ascertain
the impact of replacing coal with natural gas on an
energy equivalent basis, without any other change to the
glove production technology. Thus, the quantity of Grade
G coal (calorific value = 10,048 kJ/kg
[22]
) required by the
production processes was calculated and replaced with a
quantity of natural gas (calorific value = 52,200 kJ/kg)
that provided the same total energy. The recalculation of
single scores revealed that the fuel substitution reduced
the single scores of both NR_PF1 and NBR_PF1 gloves
by more than 50% (Figure 6), bringing them closer to the
levels of environmental impacts of gloves produced in
Factory 2.
3.4 |Comparison of gloves
3.4.1 |NR gloves (NR_PF1) versus NBR
gloves (NBR_PF1)
A comparison of each impact category for NR_PF1 and
NBR_PF1 for the same functional unit (Figure 4) showed
higher values for NR_PF1 in all impact categories except
MRD. In terms of the overall impact, NR_PF1 had higher
weighted contribution to the overall environmental
impacts than NBR_PF1 (Figures 5(A)). Figure 5(B) rev-
ealed higher single scores for chemicals, production and
combustion of fuel, and glove disposal stage for NR_PF1
than NBR_PF1. As both NR_PF1 and NBR_PF1 were
produced by using the same technology and production
process, the greater environmental impact of NR_PF1
was directly related to the different rubber latex types
(i.e., NR and nitrile latexes). A change in latex type from
NR to nitrile, or vice versa, affected the types and quanti-
ties of the chemicals needed for glove production. A LCA
revealed that use of nitrile latex reduced the energy
required for drying the glove and the sulfur required for
vulcanization. Therefore, NBR_PF1 released less sulfur
dioxide (SO
2
) in the disposal stages than NR_PF1. This
was confirmed by the low contribution of the disposal
stage of NBR_PF1 for the category TA (Table 1), which
was mainly influenced by the atmospheric release of SO
2
.
Nitrogen oxides (NO
x
), ammonia (NH
3
), and
hydrochloric acid (HCl) also contributed to TA, but less
than SO
2
.
[23]
The production of nitrile latex was another important
contributor to the total single score of NBR_PF1
(Figure 5(B)). The single score for the nitrile latex pro-
duction was noticeably high compared to the single
scores associated with the production of fresh NR latex
and its concentrated form. As the nitrile latex was pro-
duced from petroleum, its production contributed greatly
to the impact category fossil depletion (FD), and the
residual chemicals from its decomposition could
FIGURE 4 The total
characterization results per one
functional unit (FU) of gloves.
See Table 1 for explanation of
the acronyms shown below the
bars. See caption of Figure 2 for
explanation of glove types
186 PATRAWOOT ET AL.

contaminate soil, enhancing its impact in category TA
(Figure 2(B)).
[24]
The main contribution of fresh NR latex
to environmental impacts was in category ME (Figures 2
(A), (C), (D)). ME related to eutrophication of marine
environment (i.e., excessive growth of algae and marine
plants) caused by excess inputs of inorganic nutrients
such as nitrates from fertilizers to the marine ecosys-
tem.
[25]
Eutrophication is linked to leaching of nitrates
from the rubber plantations to rivers and then to the
marine environment. Nitrate is also contributed by the
atmospheric release of NO
x
from nitrogen fertilizers used,
and the diesel burnt, at the plantation. In the atmo-
sphere, natural processes convert NO
x
to nitrate which
ultimately rains back to Earth, to upset the nitrogen bal-
ance in water bodies and other ecosystems.
[26]
Although
the NO
x
emissions were on land, SimaPro 9.0.0.48
accounted for their impact on the marine ecosystem.
3.4.2 |Powder-free NR gloves (NR_PF2)
versus powdered NR gloves (NR_PP2)
Comparisons of equal functional units of NR_PF2 and
NR_PP2 for individual impact categories and the overall
impact showed higher values for NR_PF2 in all impact
categories (Figure 4) and in single scores (Figure 5(B)).
The single scores of production of fresh NR latex and of
concentrated latex were identical for both glove types
because identical technologies applied to latex production
and concentration for both glove types. Thus, the greater
environmental impact of NR_PF2 was directly related to
the additional chlorination and drying processes applied
to NR_PP2 in order to produce NR_PF2, as displayed in
Figure 1. Life-cycle analysis based on the collected data
showed that the chlorination process was the direct cause
of higher single scores of chemicals and the glove
FIGURE 5 Single scores
(millipoint, mPt) for four glove
types, based on production of
1 functional unit (FU) of gloves,
classified by boundaries (A) and
activities (B). “Concentrated latex”
in the legend of Figure 5(A) means
natural rubber (NR) concentrated
latex (excluding production of fresh
NR latex) for NR gloves, and nitrile
latex for nitrile gloves. Numbers 1–9
below the vertical bars in Figure 5
(B) denote: (1) production of fresh
NR latex; (2) production of
concentrated latex;
(3) transportation of materials to a
glove factory; (4) chemicals;
(5) packaging; (6) production and
combustion of the fuel used;
(7) electricity; (8) wastewater; and
(9) disposal of waste gloves. The
data under Figure 5(B) are single
scores of each activity for specified
glove types. See caption of Figure 2
for explanation of glove types
PATRAWOOT ET AL.187

disposal stage. The drying process after the chlorination
treatment increased the energy use by a factor of 1.5 and
hence, was the cause of a higher single score related to
the production and combustion of the fuel.
3.4.3 |Comparison of technologies of
powder-free glove production
NR_PF1 and NR_PF2 represented two technologies of
producing powder-free gloves. Their production used dif-
ferent fuels and chemicals. To produce one FU (100 pairs
of gloves), much higher values for NR_PF1 were
observed in all impact categories, except OD emissions
(Figure 4) and in most single scores (table in Figure 5
(B)). This was because the NR_PF1 technology used coal
as a fuel (Figures 2, 3) and more sulfur was used in the
vulcanization step. The significantly higher OD emissions
of NR_PF2, compared to NR_PF1 (Figure 4), were linked
to the use of natural gas in the glove production processes
of NR_PF2 (Figures 2, 3). In addition, the higher sulfur
contained in NR_PF1 led to its higher single score at the
glove disposal stage compared to NR_PF2 (Figure 5(B)).
3.4.4 |Hotspots for each glove type
Comparison of all four glove types by using the single-
score approach revealed certain environmental impact
hotspots for each glove type. These are summarized in
Table 2 for possible use in future mitigation through
redesign of the production processes. Overall, the
production stage was the main contributor to environ-
mental impacts. In keeping with the present study, the
dominant contribution of the production stage to the
environmental impacts of rubber gloves was also reported
by others.
[11]
A significant environmental impact of the
chemicals used during the production stage has also been
highlighted.
[11]
The type of fuel used had a major influence on envi-
ronmental impacts, with coal contributing to several of the
identified hotspots. As shown in Figure 6, replacing coal
with natural gas had the potential to lower the overall
impact by more than 50%. A fuel change from coal to nat-
ural gas may be easily implemented in existing production
process. Yet, the overall environmental impacts of
NR_PF1 and NBR_PF1 were still higher than NR_PF2
and NR_PP2, with the latter being the lowest among all
four glove types (Figures 5(A) and 6). After fuel substitu-
tion, the replacement of chemicals used in the production
stages of NR_PF1 and NBR_PF1 became the next environ-
mental impact hotspot issue (Table 2), followed by devel-
opment of a lower sulfur formula for NR_PF1 (to reduce
the impact of the disposal stage) and similar improve-
ments to production of nitrile latex for NBR_PF1.
Furthermore, the environmental impact of glove
types NR_PP2 and NR_PF2 can potentially be reduced by
identifying alternative chemicals with lower impacts.
Minimization of natural gas use in the drying process for
NR_PF2 is also important.
4|CONCLUSION
The life cycles of NR and nitrile gloves (powdered and
powder-free gloves) produced in two factories in
Thailand were compared using a cradle-to-grave life cycle
analysis approach for identical FU (100 pieces of gloves).
FIGURE 6 Effect of replacing coal with natural gas (NG) in
the glove production stage of powder-free natural rubber
(NR) gloves from Factory 1 (NR_PF1) and powder-free nitrile
gloves from Factory 1 (NBR_PF1), based on production of 1 FU of
gloves. The single scores (millipoint, mPt) of concentrated latex
were determined by using cradle-to-gate approach. “Concentrated
latex (cradle-to-gate)”means NR concentrated latex (including
fresh NR latex production) for NR gloves, and nitrile latex for
nitrile gloves. See caption of Figure 2 for explanation of glove types
TABLE 2 Summary of top three environmental impact
hotspots for each glove type, based on production of 1 FU of gloves
Glove
type
a
Hotspots
b
NR_PF1 Fuel production and combustion > Chemicals >
Glove disposal
NBR_PF1 Fuel production and combustion > Chemicals >
Nitrile latex
NR_PF2 Fuel production and combustion > Chemicals >
Electricity
NR_PP2 Chemicals > Fuel production and combustion >
Packaging
a
Powder-free NR gloves from Factory 1 (NR_PF1); powder-free nitrile gloves
from Factory 1 (NBR_PF1); powder-free NR gloves from Factory 2
(NR_PF2); powder coated NR gloves from Factory 2 (NR_PP2).
b
In descending order of single scores.
188 PATRAWOOT ET AL.

The assessment revealed that with current technologies
of glove production, regardless of whether powdered or
powder-free gloves are produced, the glove production
stage dominated the environmental impacts. At the raw
materials stage, the nitrile latex contributed to the envi-
ronmental impacts more than the NR latex, but at the
production stage nitrile gloves consumed less energy and
less sulfur for vulcanization. This led to a lower overall
environmental impact, or the total single score, of the
nitrile gloves than the NR gloves. Furthermore, a com-
parison of the powder-free NR gloves and powdered NR
gloves showed that the chlorination process with its
requirement of additional drying, energy and chemicals,
increased the overall environmental impact of powder-
free NR gloves. In addition, the glove-production technol-
ogy using coal as fuel was found to contribute more to
the environmental impacts than the technology that used
natural gas. While NR gloves had higher overall environ-
mental impact than nitrile gloves, the difference was rela-
tively small (10%–20%). The NR gloves had the benefit of
using renewable resources.
Life cycle environmental impact of a glove is but
one factor that influences customer choice, usually
only if the other key functional attributes of the avail-
able products are equally satisfactory. For gloves, prop-
erties such as puncture and tear resistance,
stretchiness, and barrier properties, are other impor-
tant considerations.
ACKNOWLEDGMENTS
Financial support for research was provided by Thailand
Research Fund (RDG5850025). Financial support for
publication was provided by National Research Council
of Thailand (NRCT).
CONFLICT OF INTEREST
None to declare.
ORCID
Thierry Tran https://orcid.org/0000-0002-9557-3340
Yusuf Chisti https://orcid.org/0000-0002-0826-7012
Nanthiya Hansupalak https://orcid.org/0000-0002-
9917-403X
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How to cite this article: Patrawoot S, Tran T,
Arunchaiya M, Somsongkul V, Chisti Y,
Hansupalak N. Environmental impacts of
examination gloves made of natural rubber and
nitrile rubber, identified by life-cycle assessment.
SPE Polymers. 2021;2:179–190. https://doi.org/10.
1002/pls2.10036
190 PATRAWOOT ET AL.