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Contamination of Canadian and European bottled waters with antimony
from PET containers
William Shotyk,* Michael Krachler and Bin Chen
Received 15th December 2005, Accepted 12th January 2006
First published as an Advance Article on the web 20th January 2006
DOI: 10.1039/b517844b
Using clean lab methods and protocols developed for measuring Sb in polar snow and ice, we
report the abundance of Sb in fifteen brands of bottled water from Canada and forty-eight from
Europe. Comparison with the natural abundance of Sb in pristine groundwaters, water bottled
commercially in polypropylene, analyses of source waters prior to bottling, and addition of
uncontaminated groundwater to PET bottles, provides unambiguous evidence of Sb leaching from
the containers. In contrast to the pristine groundwater in Ontario, Canada containing 2.2 1.2
ng l
1
Sb, 12 brands of bottled natural waters from Canada contained 156 86 ng l
1
and 3
brands of deionized water contained 162 30 ng l
1
; all of these were bottled in PET containers.
Natural water from Ontario bottled in polypropylene contained only 8.2 0.9 ng l
1
.
Comparison of three German brands of water available in both glass bottles and PET containers
showed that waters bottled in PET contained up to 30 times more Sb. To confirm that the
elevated Sb concentrations are due to leaching from the PET containers, water was collected in
acid-cleaned LDPE bottles from a commercial source in Germany, prior to bottling; this water
was found to contain 3.8 0.9 ng l
1
Sb (n= 5), compared with the same brand of water
purchased locally in PET bottles containing 359 54 ng l
1
(n= 6). This same brand of water in
PET bottles, after an additional three months of storage at room temperature, yielded 626 15
ng l
1
Sb (n= 3). Other German brands of water in PET bottles contained 253–546 ng l
1
Sb
(n= 5). The median concentration of Sb in thirty-five brands of water bottled in PET from
eleven other European countries was 343 ng l
1
(n= 35). As an independent check of the
hypothesis that Sb is leaching from PET, the pristine groundwater from Canada (containing 2.2
1.2 ng l
1
Sb) was collected from the source using PET bottles from Germany: this water
contained 50 17 ng l
1
Sb (n= 2) after only 37 days, even though it was stored in the
refrigerator, and 566 ng l
1
after six months storage at room temperature.
Introduction
Antimony is a potentially toxic trace element with no known
physiological function, but its natural and anthropogenic
geochemical cycles are poorly understood.
1
Found at the
surface of the earth mainly in the form of relatively insoluble
metal sulfides, its abundance in crustal rocks (ca. 0.3 mg kg
1
)
is lower than that of Pb (15 mg kg
1
) or As (1.5 mg kg
1
), two
elements with which Sb is often compared.
2
We have recently
shown that the natural abundance of Sb in uncontaminated
groundwaters may be very low. For example, in pristine
groundwaters from a calcareous aquifer in southern Ontario,
Canada,
3
the average Sb concentration was only 2.2 1.2 ng
l
1
(n= 34). The reliable measurement of Sb at these
concentrations was only made possible by the recent develop-
ment of procedures and methods for measuring Sb in polar
snow and ice,
4
including the use of clean lab facilities, metal-
free Class 100 laminar flow clean air cabinets, and inductively
coupled plasma-sector field mass spectrometry (ICP-SMS). In
this regard, the limit of detection (LOD) which has been
achieved (0.03 ng l
1
) allows Sb to be measured in even the
most dilute geological and biological fluids.
In contrast to the very low concentrations of Sb recently
presented for pristine groundwaters, most published studies of
Sb in bottled waters report much higher values.
3
For example,
in a study of bottled waters from Canada, Dabeka et al.
5
found that 42 mineral waters averaged 320 ng l
1
Sb and 102
springwaters averaged 300 ng l
1
; these average values are
more than 100 times greater than average abundance of Sb
which we found
3
in pristine groundwaters from southern
Ontario, Canada (2.2 1.2 ng l
1
). In a study of 56 bottled
waters from Europe, the median Sb concentration was 165 ng
l
16
which is high compared to its abundance in groundwaters
from Norway where values are typically on the order of ca. 30
ng l
1
but often less than 2 ng l
1
.
7
A study of Sb in bottled
waters from Japan reported Sb above the limit of detection
(500 ng l
1
) in 16 out of 55 brands.
8
Comparison of our data
for pristine groundwaters from Canada (2.2 1.2 ng l
1
) with
published data for bottled waters leads us to ask whether the
Sb concentrations reported for the bottled waters truly reflect
Institute of Environmental Geochemistry, University of Heidelberg,
INF 236, D-69120 Heidelberg, Germany. E-mail: shotyk@ugc.uni-
heidelberg.de; Fax: 54 5228; Tel: þ49 (6221) 54 4803
288 |J. Environ. Monit., 2006, 8, 288–292 This journal is cThe Royal Society of Chemistry 2006
PAPER www.rsc.org/jem |Journal of Environmental Monitoring
the Sb concentrations originally present in the natural waters
prior to bottling, or whether they possibly reflect an additional
contribution from the containers in which many of the waters
are sold.
The reasons for the large concentration differences between
pristine groundwaters and bottled waters warrants critical
examination. While geological differences certainly may play
a role, we suspect that part of the difference is because of the
inadequate LOD provided by most of the analytical methods
employed in the past for measuring Sb in waters, including
GFAAS, HG-AAS, HG-AFS, ICP-QMS, and even INAA.
3
However, a complicating factor is the widespread use of Sb in
the manufacture of plastics, and the effects of these on
laboratory blank values appear to have been inadequately
considered. We have shown, for example, that the lid of a
plastic urine collection jar contained more than 100 mg kg
1
Sb.
3
Morever, a plastic dispenser commonly used to handle
acids in the lab created a profound Sb contamination problem,
with several mgl
1
Sb found in the dispensed HCl, compared
with tens of ng l
1
Sb in the acid itself.
3
As a result, it is at
present unclear whether the reported values for Sb in bottled
waters are accurate reflections of the abundance of Sb origin-
ally present in the fluid, or whether the measured Sb concen-
trations represent a contamination artefact. The release of Sb
from plastics into fluids might have wider implications for the
scientific communities studying environmental and health
aspects of antimony.
In this context, PET (polyethylene terephthalate) is of
particular relevance. A polyester of terephthalic acid and
ethylene glycol, 90% of the PET manufactured worldwide
employs Sb
2
O
3
as a catalyst.
9
Antimony trioxide is a suspected
carcinogen, and is listed as a priority pollutant by the US EPA,
the EU, and the German Research Foundation. Currently, an
estimated 150 billion bottles are produced annually using PET.
According to Nishioka et al.,
10
some PET bottles used for
drinks in Japan contain Sb, but others do not: he found that
Sb concentrations were either in the range 170 to 220 mg kg
1
Sb, or they were below the limit of detection (o0.1 mg kg
1
).
Although there have been several studies of Sb and other trace
elements in bottled waters, no clear connection has yet been
made between the abundance of Sb in the waters and the
composition of the container materials, primarily because of
inadequate detection limits,
8,11
even when preconcentration is
employed.
12
Studies of Sb release from PET into food simu-
lants using INAA
13
suffered from high detection limits, but
experiments employing ICP-QMS documented leaching of Sb
from PET using 3% acetic acid at 40 1C for 10 days and 100 1C
for 2 hours.
14
Given that the natural abundance of Sb in groundwaters
may be in the order of a few parts per trillion
3
and our clean
lab facilities present an opportunity to measure Sb at concen-
trations of parts per quadrillion,
4
the quantitative determina-
tion of this element in bottled waters should provide a sensitive
measure of the effects of the containers on the fluids. The main
objective of this small study is to determine whether the
elevated concentrations of Sb reported in bottled waters are
simply a reflection of geological and mineralogical diversity of
the source regions, or whether they have become contaminated
by the bottles used to contain them.
Materials and methods
We purchased 15 popular brands of water bottled in PET
containers from Canada as well as 48 from Europe: Germany
(13), France (9), Switzerland (4), Finland (4), Czech Republic
(4), Denmark (3), Spain (3), Poland (2), Belgium (2), The
Netherlands (2), and Italy (2). Three of the brands from
Germany were purchased both in PET and in glass bottles;
these are denoted Brands A, B, and C. We also had the
opportunity to collect water directly from the source of Brand
A, prior to filtration and bottling, on July 18th, 2005. Wearing
polyethylene gloves and a hair net, samples were collected
directly into acid-cleaned, 100 ml low density polyethylene
(LDPE) bottles to which high purity HNO
3
(100 ml) had
already been added. This acid is produced in-house, purified
twice by sub-boiling distillation, and has an average Sb
concentration of o0.03 ng l
1
. Addition of 100 ml of this acid
to 100 ml of pristine groundwater from Canada reduced the
pH to 1.7 which is sufficient to stabilise the trace metals until
the samples could be measured. To minimise the risks of
contamination, none of the water samples were filtered. For
comparison with these waters bottled in PET, a natural water
from Ontario, Canada, bottled commercially in polypropy-
lene, was analysed for comparison.
Our LDPE bottles had been prepared in the same manner as
the bottles which have successfully been used to measure trace
elements in polar snow and ice.
15,16
All cleaning procedures
and sample manipulations were carried out in metal-free
laminar flow clean benches of US class 100 with the operator
wearing PE gloves. The 100 ml LDPE bottles and screw caps
used for the collection of waters were initially rinsed five times
with high purity water (18.2 MOcm
1
) supplied from a
MilliQ-Element system (Millipore, MA, USA). Thereafter
the bottles were filled with 10% nitric acid for 3 weeks. This
acid had been prepared in-house and was distilled twice by
sub-boiling, using a commercial instrument made of high
purity quartz (MLS, Leutkirch, Germany). Similarly, the
screw caps were submerged into 10% HNO
3
and left in the
clean bench for 3 weeks, before both the bottles and the caps
were again rinsed with high purity water and filled with 1%
HNO
3
for another week. Subsequently, the bottles and caps
were rinsed again five times with high-purity water and dried
in the clean bench overnight, before adding 100 ml high purity
HNO
3
to the bottles and sealing the bottles with the screw cap.
For practical reasons and to reduce the risk of contamination
during sampling, the acid was added to each bottle in the lab.
Bottles containing acid were then packed individually in
plastic bags, and sealed for transport to the field.
The average concentration of Sb in 15 independent blank
solutions containing 0.5% HNO
3
was 43 10 pg l
1
and
mainly reflects the contribution of Sb from the high purity
water and not that of the acid. Analyses of different HNO
3
concentrations (0.5%, 1%, 2%, 5%, 10%) produced compar-
able signals, i.e. increasing acid concentrations had no detect-
able influence on the Sb signal intensity. Therefore, Sb
contributions from HNO
3
are below the detection limit of
0.03 ng l
1
.
Water samples collected from the source at Brand A were
packed into three ziplock plastic bags and kept cool until they
This journal is cThe Royal Society of Chemistry 2006 J. Environ. Monit., 2006, 8, 288–292 |289
could be refrigerated in the laboratory in Heidelberg (ca. four
hours later). Although these samples were not analysed until
four months after collection, there was little risk of contam-
ination during storage. Our previous measurements of Sb in
groundwaters from Canada showed that even after six months
of storage in the refrigerator, there was no detectable con-
tamination of the waters by Sb from the acid-cleaned LDPE
containers.
3
All samples of bottled water were handled in metal-free
Class 100 clean air cabinets. Antimony and other selected trace
elements, including Pb and U, were determined in the waters
using inductively coupled plasma-sector field mass spectro-
metry (ICP-SMS) applying ultra clean techniques as pre-
viously adapted for the determination of trace elements in
polar ice.
15,16
To this end, a tandem spray chamber arrange-
ment including a low flow PFA nebulizer (ESI) operated in the
self-aspirating mode, was employed. Details about instrument
settings, acquisition and evaluation parameters are given else-
where.
17
For quality control purposes, SLRS-4, a certified, standard
reference material (river water) produced by the National
Research Council of Canada was analysed along with the
samples. The measured concentrations of Sb (224 12 ng l
1
,
n= 17) agreed well with the certified value (230 40 ng l
1
).
Results
Bottled waters from Canada
Compared to the natural abundance of Sb in pristine ground-
waters from Springwater Township, Ontario (2.2 1.4 ng l
1
,
n= 34), twelve brands of water from Canada, all in PET
bottles, contained 112–375 ng l
1
(n= 21). Of these twelve
brands, eight were bottled in the same region of southern
Ontario as the ‘pristine groundwater’ described earlier.
3
Given
that southern Ontario consists of a series of sedimentary
platforms, it seems unlikely that geological variation can
explain these pronounced differences in Sb concentrations.
Moreover, the three brands of deionised water bottled in PET
from Ontario contained 134–195 ng l
1
Sb. Given that deio-
nised water should contain very low concentrations of Sb (e.g.
o0.1 ng l
1
), the comparatively high concentrations of Sb in
bottled deionised waters suggests that there is leaching of Sb
from the bottles. Finally, the natural water from Ontario
which is packaged in polypropylene (PP) bottles contains only
8.2 0.7 ng l
1
(n= 7); this was the only bottled water found
to contain concentrations of Sb comparable to the pristine
groundwaters from southern Ontario. Taken together (Fig. 1),
this data suggests that all of the waters bottled in PET
containers, both the natural waters as well as deionised waters,
have become contaminated with Sb leaching from their con-
tainers.
Bottled waters from Europe
The results of the Sb determinations of waters sold by Brands
A, B, and C in Germany are given in Table 1. Water collected
at the source of Brand A, prior to filtration and bottling,
yielded 3.8 0.9 ng l
1
Sb (n= 5), compared with the same
brand of water purchased locally in PET bottles containing
359 54 ng l
1
(n= 6). These six bottles of Brand A in PET
were purchased a few days prior to measurement. However,
this same brand of water in PET bottles, purchase three
months earlier and stored at room temperature, yielded
626 15 ng l
1
Sb (n= 3). These results show unambiguously
that there is a profound leaching of Sb from the PET container
into the water. The increase in Sb concentrations (75% during
three months storage of Brand A), represents a leaching rate of
approximately 100 ng l
1
per month. Analyses of Sb in water
from Brand B and C, in glass bottles versus PET, supports this
interpretation (Table 1). In the case of Brand C, the water
bottled in PET contains approximately 10 times more Sb than
the water stored in glass bottles. In the case of Brand A, the
water bottled in PET contains 95 to 165 times more Sb than
the original source water, depending on the time of storage.
Moreover, the data suggests that the Sb concentration in the
waters bottled in PET are independent of the natural abun-
dance in the source water, but rather dependent on the time of
reaction between the bottle and the fluid (i.e. the duration of
storage).
Five other brands of water from Germany bottled in PET
contained 253–546 ng l
1
Sb (n= 5). Three other brands of
water from Germany, bottled in plastic bottles which were not
identified as PET, but rather as ‘recyclable’ contained only
32–60 ng l
1
Sb (n= 3). In this latter case, it may be supposed
that either these bottles are made of a polymer or polymers
which do not employ Sb as catalyst, or they had previously
been recycled a sufficient number of times to have leached Sb
out of the surface layers of the bottle walls.
With respect to the thirty-five brands of water in PET
bottles from other countries in Europe (Fig. 2), the median
Sb concentration is 343 ng l
1
(n= 35). The lowest concen-
tration found (6 ng l
1
) was in a sample from Poland, but
based upon all of our data to date, we suspect that this bottle is
either not made of PET, or it is made of PET manufactured
without the use of Sb.
9
The data shown in Fig. 2 indicates that
the range in Sb concentrations is rather limited, with most
values within a factor of two of the median. In contrast, our
measurements of Pb and U in these same suite of samples
Fig. 1 Antimony concentrations (ng l
1
) in waters from Canada:
pristine groundwater, Springwater Township, Simcoe County, Ontar-
io,
3
12 brands of natural water in PET containers, 3 brands of
deionized water, and one brand of natural water bottled commercially
in polypropylene.
290 |J. Environ. Monit., 2006, 8, 288–292 This journal is cThe Royal Society of Chemistry 2006
show far greater variations: Pb varies from 0.7 to 1008 ng l
1
(more than 3 orders of magnitude) and U from 0.077 to 21 550
ng l
1
(more than 5 orders of magnitude). The large variations
in the abundance of Pb and U in these waters are a reflection
of the geological and mineralogical diversity of the source
areas. The abundance of Sb in the waters, however, appears to
be independent of geology.
Although there is a strong geochemical and mineralogical
association between Pb and Sb at the surface of the earth,
1
there is no correlation between the abundance of Sb in waters
bottled in PET, and the abundance of Pb. We note further that
the natural abundance of Pb to Sb in typical freshwaters is
15 : 1.
18
For comparison, our measurements of Pb and Sb in
pristine groundwaters from Canada indicate that the ratio of
Pb to Sb is approximately 10 : 1 (Shotyk, unpublished). In the
waters bottled in PET from the countries shown in Fig. 2, the
median Pb concentration is 5 ng l
1
. Assuming that the
natural ratio of Pb to Sb in pristine groundwaters is ca.
10 : 1, the median Pb concentration (5 ng l
1
) implies that a
median Sb concentration of 0.5 ng l
1
could reasonably be
expected. However, the median Sb concentration in the Eur-
opean bottled waters is 343 ng l
1
Sb. These results and
arguments imply that the waters bottled in PET have a much
greater ratio of Sb to Pb, by many hundreds of times,
compared to the ratio of their occurrence in nature. We
assume, based on our measurements to date, that all of the
waters bottled in PET, except one brand from Poland, have
become contaminated with Sb leaching from the bottles.
To independently confirm that PET containers can have a
significant effect on the Sb concentration in the fluids they
contain, one of the PET bottles from Brand A was rinsed with
pristine groundwater (containing 2.2 1.2 ng l
1
Sb) at an
artesian flow (Lot 5, Concession 10, Springwater Township,
Ontario, Canada), allowed to leach for several days, and
rinsed again with this water. Following the leaching and
rinsing, it was filled with the pristine groundwater and shipped
airfreight in a cool box to our lab in Germany. After only 37
days storage, in the refrigerator, this water was found to
contain 59 17 ng l
1
Sb (n= 2). In an earlier experiment
using this approach, this same pristine water, after storage in
the same brand of PET bottle at room temperature for six
months, yielded 566 ng l
1
Sb (n= 1), an increase of more
than 250 times.
Discussion
Contamination of bottled waters from Sb in PET versus glass
containers
The data shown in Table 1 shows not only that water bottled
in PET is contaminated with Sb, but also the water bottled in
glass. Therefore, the natural abundance of Sb in groundwaters
can neither be obtained from waters stored in PET nor in glass
containers. Using instrumental neutron activation analyses
(INAA), we found that a PET bottle for water (Brand A)
and one for cola contained 397 and 351 mg kg
1
Sb, respec-
tively; these very high concentrations certainly reflect the use
of Sb
2
O
3
as a catalyst in the manufacture of PET.
9
However,
we also used INAA to measure Sb in one glass bottle used for
water (Brand A) and one for cola; these contained 7.6 and 10.1
mg kg
1
Sb, respectively. The presence of Sb in the glass
bottles probably reflects its use as an opacifier in the manu-
facture of glass. Even in glass bottles, therefore, some leaching
of Sb into waters has to be expected. Although our data
suggests that leaching of Sb from PET is far greater than
from glass, our study included 48 brands of water in PET, but
was limited to only 3 brands in glass. No general conclusions
about the extent of leaching of Sb into waters from glass
bottles should be made based on the limited number of
samples considered in the present study.
Factors affecting the leaching of Sb from the PET containers
The results presented here give rise to many questions regard-
ing the chemical and mineralogical forms of Sb in PET
containers, spatial variation in Sb concentrations within these
polymers, and the release of Sb to bottled waters and other
beverages. For example, what is the relationship between the
concentration of Sb in the polymer and its rate of release to the
water? How does this rate vary with the pH of the water,
temperature, presence of other cations and anions, storage
conditions, and reaction time? How much of the Sb in the
beverage is in the form of Sb(III) and how much Sb(V)? With
Table 1 Variations in Sb concentrations (ng l
1
) within a given brand of commercially bottled mineral water (glass versus PET) and between
brands (n= number of bottles analysed). N/A = not available
Brand Source Glass PET (purchased October, 2005) PET (purchased July, 2005)
A 3.8 0.9 (n= 5) 11.5 4.4 (n= 6) 359 54 (n= 6) 626 15 (n=3)
B N/A 84.5 10.2 (n= 6) 255 20 (n=6)
C N/A 26.4 3.1 (n= 6) 301 43 (n=6)
Fig. 2 Antimony concentrations (ng l
1
) in European mineral waters
bottled in PET. The data for the water samples from Germany are
given in Table 1 and in the text.
This journal is cThe Royal Society of Chemistry 2006 J. Environ. Monit., 2006, 8, 288–292 |291
respect to acidic drinks (vinegar, fruit juices, cola, lemon juice)
what is the effect of pH on the Sb release rate? What is the
effect of citric acid and other organic ligands on the release
rate? Also, what is the effect of conditioning of the bottles by
washing during recycling and reuse?
Conclusions
The data presented here leave little doubt that bottled waters
stored in PET are contaminated with Sb from their containers.
The motivation for our study has been to demonstrate that
bottled waters cannot be used to study the natural abundance
of Sb in groundwaters. Moreover, Sb is widely used in plastics
commonly found in many laboratories. We suspect that
sample contamination by Sb-bearing containers and sample
handling equipment is more widespread than generally rea-
lised. We note further that PET is used not only for drinks
bottles, but also for filtering beverage products, food packa-
ging, and in the pharmaceuticals industry.
We wish to emphasise that all of the waters measured in our
lab to date were found to contain Sb in concentrations well
below the guidelines commonly recommended for drinking
water which are as follows: WHO, 20 ug l
1
; US EPA, Health
Canada and the Ontario Ministry of Environment, 6 ug l
1
;
German Federal Ministry of Environment, 5 ug l
1
; Japan,
2ugl
1
. However, given that there appears to be a continual
release of Sb from the containers to the fluids, and that the Sb
concentrations in the waters mainly reflect the duration of
storage, systematic studies of the extent and intensity of
contamination are warranted.
Acknowledgements
We are grateful to Stefan Rheinberger and James Zheng for
technical support, and to Andriy Cheburkin for helpful dis-
cussions. Emma and Olivia Shotyk helped with the field work
in Germany. We thank the following friends and colleagues
for providing bottles of water: Gae
¨l Le Roux, Tommy Nørn-
berg, Kimmo Virtanen, and Henrik Wild.
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