|June 24, 2003: "Perchlorate"
has been on the lips of the media but, unfortunately, not the EPA
scientists familiar with two recently released studies revealing the
rocket-fuel component may be contaminating the winter lettuce feeding
88% of the USA's population. A gag order imposed by the EPA prevents
the scientists from speaking about perchlorate and, therefore, the
studies, which show lettuce not only absorbs but also concentrates
perchlorate in substantial amounts.
||"...researchers at Texas Tech University...
concluded that 1.6 million U.S. women of childbearing age are
exposed daily to more perchlorate from winter lettuce alone
than the EPA's recommended 'safe dose.'"
Concerns about rocket fuel, specifically perchlorate, contamination
surfaced last year when the EPA announced research findings that
concentrations of the chemical in drinking water above one part
per billion pose a health risk to humans, particularly in developing
infants. To put this number in perspective, you should know that
the Colorado River, which supplies over 15 million people with drinking
water, is polluted at seven parts per billion. The research recommended
contamination limit be set at five parts per billion.
The Pentagon and several defense contractors, in the face of a
multi-billion dollar cleanup, have funded more than $30 million
in research opposing the EPA's assessment and argue 70 to 200 times
the EPA's estimate of perchlorate is safe in drinking water. And,
in the name of "military readiness," the Bush administration
has proposed a bill in Congress pardoning the Pentagon and defense
industry from an array of environmental laws; forgiving their environmental
damages including perchlorate contamination. US Senator James Inhofe
(R., Okla.), chairman of the Senate's Environmental and Public Works
Committee, even publicly criticized the EPA's report in January.
So what exactly is all this lettuce hubbub about? In one study
performed by researchers at Texas Tech University, Lubbock, TX,
22 lettuce samples purchased in San Francisco Bay Area grocery stores
between January and February were tested. The group discovered four
of the 22 samples were found to contain perchlorate in amounts exceeding
30 parts per billion, with the highest -- "mixed organic baby
greens" -- registering 121 parts per billion. They concluded
that 1.6 million U.S. women of childbearing age are exposed daily
to more perchlorate from winter lettuce alone than the EPA's recommended
In case this recent press on perchlorate contamination of lettuce
has you worried, here’s a whirlwind tour of what perchlorate
is, what it’s doing in our food systems, what that might mean
to you, and what you can do about it.
What is perchlorate?
Perchlorate is the substance that has served since the 1940s as
an oxidizer in solid rocket fuel for more effective propulsion for
space shuttles and missiles. Perchlorate compounds are also used
in explosives, matches, fertilizer, fireworks, road-flares, air-bag
inflation systems, lubricating oils, nuclear reactors, electronic
tubes, and finishing processes for rubber, leather, aluminum paints,
enamels and electroplating. It is highly mobile in water, meaning
it can be easily transported in fluid, either on a large scale (for
example a river) and also on a smaller scale (e.g. vascular transport
For the scientifically-minded: A perchlorate molecule is an organochlorine
and has the chemical formula ClO4-, four oxygen atoms surrounding
a chlorine atom. Perchlorate can become an acid or a salt when bound
with a positive ion (a.k.a. cation), such as hydrogen, sodium, potassium
or ammonium. Ammonium perchlorate is the form most commonly produced.
What is perchlorate doing in our food system?
The process of washing perchlorate out of rockets has been a source
of drinking and irrigation water contamination demonstrated in and
around the Colorado River and the Sacramento area.
|"As noted by the Water Eduation Foundation,
'According to NASA, each solid rocket booster on the space shuttle
contains 700,000 pounds of perchlorate, for a total of nearly
1.5 million pounds. In years past, it was disposed of by flushing
with high-pressure water jets – a process that resulted
in wastewater with perchlorate levels at 1 percent of total
volume. Often the water was simply drained directly into the
As perchlorate loses efficacy with time, it is washed out, creating
a toxic waste product. As noted by the Water Eduation Foundation,
"According to NASA, each solid rocket booster on the space
shuttle contains 700,000 pounds of perchlorate, for a total of nearly
1.5 million pounds. In years past, it was disposed of by flushing
with high-pressure water jets – a process that resulted in
wastewater with perchlorate levels at 1 percent of total volume.
Often the water was simply drained directly into the ground."
Once in the groundwater, removing perchlorate can prove to be
a challenge. Prior to the introduction of an ion chromatography
technique in 1997, perchlorate was very difficult to detect. The
highly mobile contaminant is now much easier to trace. But, although
the procedure for removing perchlorate is not considered difficult,
the amount of contaminated water needing treatment is enormous and
poses logistical challenges.
For many years, efforts to establish a drinking water standard
for perchlorate contamination have been under way, receiving federal
and state attention. While efforts are being made to speed and ease
the lengthy regulatory process, the progression is painstakingly
slow. A slide
show presentation by McGuire Environmental Consultants, Inc.
includes a timeline of some of the regulatory actions prior to January
2002. Just last month, the possibility of regulatory action was
stalled even further when the debate was referred to the National
Academy of Sciences for review inspiring the gag on EPA scientists.
But the drinking water standard is not the end of the regulatory
process and, as the two recent lettuce studies suggest, may be a
beginning of the recognition of widespread problems related to perchlorate’s
presence in the water system. The irrigation of some of our major
agricultural land hinges on the very water sources being contaminated,
exposing consumers to perchlorate nationwide through the very food
on their plates.
What impact might perchlorate contamination of
water and food have on me?
||"Contamination of the Colorado River
means that 1.4 million acres of cropland in California and Arizona
is dosed with perchlorate at varying intensities depending on
the area from which the irrigation water is drawn"
Many sites are contamination confirmed or at high risk of being
contaminated with this rocket fuel component. The Environmental
Working group has posted a list of perchlorate-contaminated areas
Fortunately, if you are drinking uncontaminated water and eating
food that is not irrigated with perchlorate-contaminated water,
then you may not be affected at all. Unfortunately, even if you
do not live by a contaminated site, in this age of long-distance
food shipment, much of what we eat comes from farther away than
the local water supply and could be from contaminated areas.
Contamination of the Colorado River means that 1.4 million acres
of cropland in California and Arizona is dosed with perchlorate
at varying intensities depending on the area from which the irrigation
water is drawn. The Yuma and Imperial Valleys (in AZ and CA, respectively),
grow 88% of the winter lettuce that is consumed by Americans. And
lettuce is not the only crop that takes up perchlorate. Any fruit
or vegetable that is highly aqueous or leafy can be a major accumulator
What does perchlorate do in the human body?
Perchlorate disrupts the human metabolism. We all have a thyroid
gland in our necks that secretes hormones that work in concert with
other organs and glands to regulate our metabolism. Humans can be
hyperthyroid, and secrete too many thyroid hormones or hypothyroid,
secreting too few. Both conditions are detrimental. Our thyroids
take in iodide and, when healthy humans have sufficient iodide,
we produce optimum amounts of thyroid hormones T3 (triiodothyronine)
and T4 (thyroxine).
Perchlorate competes with iodide, tying up the transport mechanism
and raising production of thyroid stimulating hormone TSH (thyrotropin).
To gauge the level of someone’s exposure to perchlorate, tests
of TSH, T3 and/or T4 levels could be an indicator of problems in
Possible physical ramifications of an overexposure to perchlorate:
altered metabolic rate, thyroid lesions, thyroid
tumors, decreased T3/T4 production, hypothyroidism. In the
1960s, perchlorate was used to treat hyperthyroidism, but its long-term
use was discontinued after severe side effects were noted (including
deaths) due to aplastic anemia (http://www.thyrolink.com/literature/report1995_2/seite03.html).
There are a few high-risk groups out there, and these people should
be especially wary of perchlorate intake. Those already battling
hypothyroidism should avoid anything that would make iodide utilization
any more difficult than it already is for their bodies.
Pregnant women have thyroid stress under normal circumstances and
are, therefore, more at risk of developing a severe problem, such
as preclampsia, miscarriage, placental abruption and low birth weight,
or chronic condition when overexposed to perchlorate.
Perchlorate can also pose significant threats to the health of
the developing fetus. Children, infants, and neonates don't have
enough thyroid hormone to cushion them from the dips in hormone
production caused by the contaminant. Chronic health conditions
What can I do to lower my exposure to perchlorate?
First and foremost, know where your
food and water is coming from, and know the odds
of it being contaminated. Perchlorate is considered highly mobile
in water, but remains quite localized to its watershed, unless it
is shipped elsewhere.
If you live in Yuma Valley, are pregnant, work in a military installation
and suffer from hypothyroidism, avoid tap water and don't eat salad
from a contaminated area. Perchlorate intake is primarily via food
and drink. It is poorly absorbed through skin, so don’t be
afraid to shower or do laundry in contaminated water.
Some reduction in perchlorate contamination can be achieved simply
by washing vegetables in uncontaminated
water. But, because plants tend to accumulate perchlorate
in their leaves, washing with uncontaminated water is not enough
to rid vegetables of all contamination. You can limit perchlorate
intake simply by limiting the amount
of leafy or extremely watery vegetables you eat.
Eat more iodine-rich foods
to combat the thyroid competition posed by perchlorate presence.
Sadly, the most easily-attainable sources for iodine are iodized
salt and sea products, both of which can be taboo for pregnant women.
Cardiac patients are also recommended to restrict sodium intake,
but are often advised to eat fish.
You can also encourage more of a
systems approach to reduction, i.e. making/changing
policy, research, or ecosystem remediation (cleanup) on a local
and national level.
Bioremediation, or using natural
processes to clean up our messes, shows promise.
A 95% reduction in perchlorate contamination was achieved by non-crop
plants taking up the organochlorine and is a step in the right direction.
Unfortunately, disposal of these contaminated non-crop plants then
becomes a challenge.
Prevention is key.
A material called MnO4- may be an effective and less harmful substitution
for perchlorate. This potential substitution has not be researched
fully yet but may offer an alternative that doesn't currently exist.
And, as always, public outcry is
essential. Contact your House or Congressional representative
and let them know you support safe, clean water according to guidelines
based on science and the precautionary principle.
- air-bag inflation systems
- lubricating oils
- nuclear reactors
- electronic tubes
Also used in finishing
- aluminum paints
- altered metabolic rate
- thyroid lesions
- thyroid tumors
- decreased T3/T4 production
- aplastic anemia
And for pregnant women:
- placental abruption
- low birth weight
- drink uncontaminated
- eat uncontaminated food
- wash contaminated food
- increase iodine consumption
- eat fewer leafy/watery
- limit occupational exposure