Environmental Science & Technology  [Printer-friendly version]
March 22, 2006


[Rachel's introduction: To their surprise, German researchers have
found the toxic metal, antimony, in bottled water. They also report
that levels of antimony in the natural environment have been rising
since 1970 because humans use antimony in flame retardants.]

By Kris Christen

Once drinking water is encased in plastic bottles, its levels of
antimony tend to rise; researchers suspect that the toxic element is
leaching out of the bottles.

Consumers who drink bottled water could be getting more than they
bargained for in the form of a surprising amount of antimony, a
potentially toxic trace element with chemical properties similar to
those of arsenic. Fortunately, concentrations reported to date are too
low to trigger health alerts.

Acting on a hunch, researchers at the University of Heidelberg
(Germany) Institute of Environmental Geochemistry measured the
abundance of this heavy metal in 15 brands of Canadian bottled water
and 48 European brands. In findings published in February (J. Environ.
Monit. 2006, 8, 288-292), they reported concentrations of more than
100 times the average level of antimony in uncontaminated groundwater,
which is 2 parts per trillion (ppt).

The researchers weren't initially looking for antimony in bottled
waters. "We were just interested in characterizing a pristine
groundwater and got to wondering why a number of analyses in the
literature were reporting much higher values of antimony in bottled
waters than what we were finding," says William Shotyk, the study's
lead author.

Most commercially available bottled water is now sold in polyethylene
terephthalate (PET) containers, according to Mike Neal, chairman of
the PET Health, Safety, and Environment Committee of Plastics Europe,
an association of European plastics manufacturers. Antimony trioxide
is used as a catalyst in the manufacture of PET, which typically
contains several hundred milligrams per kilogram (mg/kg) of antimony.
By comparison, the natural abundance of antimony in rocks and soils is
less than 1 mg/kg.

Global consumption of bottled water more than doubled over the past 5
years, to 41 billion gallons (gal), according to the latest statistics
from the International Bottled Water Association (IBWA), a trade
group. People throughout the globe consumed an average of 6.4 gal of
bottled water per person in 2004, according to IBWA. In 2005, revenues
for the U.S. market alone, which is the largest consumer of bottled
water, topped $9.8 billion.

Shotyk and his colleagues found that waters bottled in PET containers
contained as much as 550 ppt of antimony. Even highly purified
deionized waters contained in PET bottles had antimony concentrations
up to 160 ppt. Moreover, "the longer the water's in the bottle, the
more antimony it's going to have," Shotyk notes.

Just to be sure that the antimony was leaching from the PET bottles,
Shotyk and his colleagues collected source water from a German
bottling company and measured 4 ppt of antimony. However, in the same
brand of water purchased from a local supermarket, "I got 360 ppt,"
Shotyk says, "and that same brand of water, but purchased 3 months
earlier and sitting in my office, contains 630 ppt."

Neal points out that these concentrations are far lower than drinking-
water standards, which range from 2 parts per billion (ppb) in Japan
to 5 ppb in Europe and 6 ppb in the U.S. and Canada. Under World
Health Organization guidelines, up to 20 ppb is considered safe.
Additionally, he notes that "all packaging materials migrate different
amounts of materials into foodstuffs, and PET is one of the polymers
that migrates the least of its contents."

But Shotyk wonders about the wider environmental implications. "That's
a lot of antimony in the plastic," Shotyk notes, and "the question is,
where does it end up?" Unlike other heavy metals, such as lead,
mercury, cadmium, and arsenic, very little research has been done to
date on the environmental fate of antimony. The U.S. EPA lists the
metal as a possible carcinogen and priority pollutant. Previous
studies by Shotyk and his colleagues on ice cores from the Canadian
Arctic show that antimony enrichment from aerosols migrating there is
50% higher today than it was 30 years ago.

Although antimony has been used since ancient times, consumption has
risen dramatically since the early 1970s with the advent of flame
retardants, says James Carlin, a commodity specialist with the U.S.
Geological Survey (USGS). China now produces 85% of the world total.
The mining and processing of antimony ores is a primary source of
antimony to the environment, according to a toxicological profile by
the U.S. Agency for Toxic Substances and Disease Registry. Smaller
amounts are also released by waste incinerators and coal-burning power

More than half of the antimony goes into flame retardants. The rest is
used mainly in glass for television picture tubes and computer
monitors, pigments, stabilizers and catalysts for plastics,
ammunition, friction bearings, lead-acid batteries, and solders, USGS
statistics show.

Copyright 2006 American Chemical Society