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By Ken Cook,
President of the Environmental Working Group
Fish is beyond compare as a source of
many nutrients vital to the developing infant, some of which may actually
enhance development of the nervous system in babies and young children.
Widespread
contamination of fish with toxic mercury, however, has cast a shadow over
the nutritional benefits of fish.
Exposure to mercury in the womb can
cause learning deficits, delay the mental development of children, and
cause other neurological problems. Mercury consumed by a pregnant woman
through contaminated fish can cross her placenta to damage the brain of her
baby.
As a National Academy of Sciences panel
definitively warned last year, some children exposed in utero by their
mothers' fish consumption are at risk of falling in the group of children
"who have to struggle to keep up in school and who might require
remedial classes of special education."
Combustion in power plants of coal
containing mercury is the major source of environmental
pollution.
40 Tons of
Mercury are released into the US EVERY year by this method.
Mercury pollution from coal-fired power
plants moves through the air, is deposited in water and finds its way into
fish, accumulating especially in fish that are higher up the food chain.
Fish like tuna, sea bass, marlin and halibut show some of the worst
contamination, but dozens of species and thousands of water bodies have
been seriously polluted.
As a
result, women who eat a lot of fish during pregnancy, or even as little as
a single serving of a highly contaminated fish, can expose their developing
child to excessive levels of mercury. The toxic metal can cross the
placenta to harm the rapidly developing nervous system, including the
brain.
In this report, EWG researchers for the
first time attempt to characterize just how common such exposures are in
the U.S. population, and the associated risks.
One key to the analysis is a much more
refined representation of differences among women - their size, metabolism
of mercury, blood volume, and many other biological variables. Government
assessments use "averages" or constants for all of these factors,
missing profound differences across the population of women of child
bearing age.
EWG
analysts also assembled the most extensive database ever developed on
mercury levels in various species of fish, drawing on federal, state and
other government sources, some 56,000 records in all.
That exercise revealed major variations
in mercury contamination across fish species, yielding vital, highly
practical information women can use while pregnant to reduce mercury
exposure dramatically, while still enjoying the nutritional benefits of
fish.
Earlier this year, the Food and Drug
Administration came up with its own list of fish that pregnant and nursing
women, along with infants, should avoid. Based on our analysis of much more
extensive fish contamination records, the list presented in this report is
more complete.
By analyzing these two data sources in
combination, the study is able to provide new insights into how women can
avoid excessive mercury exposures during pregnancy.
Researchers at US PIRG Education Fund, co-authors of this
study, made another vital contribution. PIRG painstakingly combed through
hundreds of "fish advisories" issued by state agencies to warn
people about mercury levels in sport and game fish in literally thousands
of US lakes and rivers.
What they found is disturbing: while
some states are doing a better job than others, virtually no fish
advisories for mercury contamination are adequately protective of human
health when judged against current scientific knowledge.
The importance of this new understanding
about mercury risks was evidenced in a landmark study on blood levels of
mercury and other toxins, released by the federal Centers for Disease
Control and Prevention (CDC) in March, 2001.
While "average" blood mercury
levels among women were not of concern, the data indicate that in fully 10 percent of
American women -- roughly 7 million women -- mercury levels were above the
dose that may put a fetus at risk for adverse nervous system effects.
Those women surely don't need more
mercury in their system, least of all if they are already pregnant or
nursing. As this report recommends, the government must start monitoring
such exposures, and any possible effects, much more energetically. This is
a simple, common sense matter of public health.
In the longer term, the solution is to
halt mercury pollution from coal-burning power plants and other sources so
the contamination of fish is avoided in the first place. Fuel switching --
from coal to renewable energy sources -- along with aggressive deployment
of conservation measures, makes sense for any number of reasons.
Fish free of mercury -- the way they
used to be -- is just another one.
Executive
Summary
On January 12, 2001, government health
officials issued new advisories warning women to limit fish consumption
during pregnancy to avoid exposing their unborn children to unsafe levels
of methylmercury.
Methylmercury can cross the placenta and
cause learning deficits and developmental delays in children who are
exposed even to relatively low levels in the womb. The principal exposure
route for the fetus is fish consumption by the mother.
The Food and Drug Administration (FDA),
which regulates commercially sold fish, recommends that pregnant and nursing
women and young children not eat any shark, swordfish, tilefish, or king
mackerel, but then recommends 12 ounces per week of any other fish.
The Environmental Protection Agency
(EPA), which makes recommendations to states about safe mercury levels in
sport fish, allows up to 8 ounces of any fish per week for pregnant women
with no prohibitions on consumption of any individual fish caught
recreationally.
These
restrictions are steps in the right direction, but they need to be
tightened significantly to adequately protect women and their unborn
children from the toxic effects of methylmercury.
The nutritional benefits of fish
complicate the task faced by health officials when protecting the public
from methylmercury. Protein, omega-3 fatty acids, Vitamin D, and other
nutrients make fish an exceptionally good food for pregnant mothers and
their developing babies.
At the same time, there is no doubt that
methylmercury is toxic to the fetal brain and nervous system, and that many
beneficial fish species are contaminated. EPA's safe exposure estimate for
methylmercury has dropped twice in the past 16 years, as new science has
identified adverse effects in children exposed in the womb at lower and
lower doses.
Emerging evidence indicates that the
safe dose may drop even lower in the future (NAS 2000). Just how long a
fetus can tolerate a dose of methylmercury above a "safe level' with
no observable adverse effects is a matter of ongoing debate.
Compounding this uncertainty is the lack
of effective education and outreach to pregnant women about methylmercury
risks and the near total absence of information for pregnant women on the
levels of mercury in the fish they buy. New data from the Centers for
Disease Control and Prevention (CDC) show that about 10 percent of all
women of childbearing age have blood methylmercury levels above the dose
that may put their fetus at risk for adverse neurological effects (CDC
2001).
If these women were to increase their
consumption of certain fish species in hopes of benefiting their babies
during pregnancy, they could expose their fetuses to potentially hazardous
levels of methylmercury.
FDA's
Protections Fall Short
FDA's methylmercury safeguards are
designed to protect an average-sized woman eating an average fish
contaminated with an average amount of methylmercury that decays in her
body at an average rate. These assumptions rarely apply to the risks faced
by any individual.
Instead, risks are unevenly distributed
throughout the population, with a small but significant number of
pregnancies exposed to far higher and potentially unsafe levels of
methylmercury than the average fetus. The 10 percent most-heavily exposed
American women already have blood methylmercury levels that would increase
health risks to their fetuses if they became pregnant (CDC 2001). FDA's
health advisory, based on average exposures, does little to protect these
children.
The
Environmental Working Group assessed fetal exposure to methylmercury
taking into account a host of real world differences in individual
exposure, including a mother's body weight and blood volume, varying
methylmercury absorption and distribution rates, and variable rates of
methylmercury decay in different pregnant women (Stern 1997, CDC 2001, NAS
2000).
These biological differences were
matched up with a unique database of fish contamination that contains
56,000 records of methylmercury test results from seven different
government sources. Fish consumption, fish contamination levels, and
biological variables were matched thousands of times to create a
distribution of blood methylmercury levels in women similar to that
occurring in the general population.
This distribution was compared to the
benchmark dose of methylmercury recommended by the Committee on the
Toxicological Effects of Methylmercury of the National Academy of Sciences
(NAS 2000).
FDA's recommendation of 76 6-ounce fish meals during pregnancy could
actually be detrimental to the health of unborn children. Fish are an important
part of a healthy diet and women should be encouraged to eat fish with low
methylmercury levels during pregnancy.
But if
American women ate a varied diet of FDA's recommended 12 ounces of fish a
week (and none of the four prohibited fish) they would expose more than
one-fourth of all babies born each year (1 million infants) to a
potentially harmful dose of methylmercury for at least one month during
pregnancy.
About
20,000 of these children would be exposed to a dose of methylmercury that
increases the risk of adverse neurological effects for the entire
pregnancy.
The EPA
and state fish advisories for sport fish
EPA provides guidance on safe
methylmercury exposure levels to state officials who in turn issue
consumption advisories for sport fish caught by recreational anglers. State
authorities typically post fish advisories for individual water bodies
where fish are contaminated with methylmercury at a level that they deem
unsafe for women of childbearing age.
Some states have done a better job than
others in protecting their populations from methylmercury, but an analysis
by US PIRG and the State PIRGs shows
that only Massachusetts has adopted health safeguards that protect all
women and children.
The broader issue with recreational
fish, however, is whether these advisories translate into conscious choices
by pregnant mothers to avoid eating contaminated fish. There is a
substantial body of evidence indicating that they do not (Golden et al
2001).
Recommendations
Fish provide important health benefits
to the developing fetus, and pregnant women should be encouraged to eat
fish with consistently low methylmercury levels. With too many species,
however, these nutritional pluses are outweighed by the hazards of
methylmercury.
Federal health authorities need to take
much stronger steps to protect a far greater portion of the population.
They must move beyond their antiquated safeguards designed to protect an
average woman from an average amount of methylmercury in fish and take a
realistic and protective stance against dietary exposure to methylmercury.
Fish
Advisories
FDA
There are three ways that the FDA
methylmercury health advisory must be improved:
1. The list of fish to avoid during pregnancy
must be expanded.
By advising against the consumption of
just four types of fish, FDA allows heavy consumption of many fish that
have unacceptably high methylmercury levels. To protect women and their
babies from methylmercury, the FDA must add the following species to the
list of seafood that should not be eaten by pregnant women, nursing women,
and women considering pregnancy:
Tuna steaks
Sea bass
Oysters (Gulf of Mexico)
Marlin
Halibut
Pike
Walleye
White croaker
Largemouth bass
While not every serving of any of these
fish is contaminated with dangerous levels of methylmercury, the odds are
greater than one in 1,000 that consumption of a single meal of these fish
will expose the fetus to a potentially hazardous amount of methylmercury
for longer than 30 days.
2. FDA's
recommendation that pregnant women eat 12 ounces a week of any fish (except
the four that are not allowed) must be radically revised.
Ten percent of American women enter
pregnancy with elevated methylmercury levels, and current FDA safeguards,
which are based on average exposures, do almost nothing to protect these
high exposure pregnancies. If these women follow FDA's advice of 12 ounces
of any fish a week, they could easily expose their fetuses to a level of
methylmercury that presents a real risk of adverse neurological effects. To
protect women and children, FDA must restrict consumption of the following
fish to no more than one meal per month, for all species combined:
Canned tuna
Mahi mahi
Blue mussels
Eastern oyster
Cod
Pollock
Salmon from the Great Lakes
Blue crab from the Gulf of Mexico
Channel catfish (wild)
Lake whitefish
3. Women who want to eat fish during pregnancy must
have information about which species are least contaminated with
methylmercury. Pregnant women
have a right to this information, and FDA has a duty to provide it. In
addition to strengthening restrictions on fish consumption by pregnant
women, FDA should promote the following fish as safe options for pregnant
women:
Trout (farmed)
Catfish (farmed)
Shrimp * (see sidebar)
Fish Sticks
Flounder (summer)
Salmon (wild Pacific)
Croaker
Blue crab (mid Atlantic)
Haddock
Freshwater
Sport Fish
It was not possible for EWG to assess
the methylmercury risk from every recreational fish caught in every lake in
every state in the country. A review of the available data, however, shows
that several large predator sport fish are so universally contaminated that
FDA should add them to the list of fish that women should completely avoid
during pregnancy.
After analyzing the results of more than
10,000 samples from 792 lakes and rivers nationwide, we recommend that FDA
add the following species to their health advisory: walleye, northern
pike, and largemouth bass. While
FDA has no authority to regulate methylmercury levels in freshwater fish,
they do have a responsibility to provide critical health information to the
public. It is important that women receive a consistent message from one
source, and the FDA is the appropriate agency to deliver this message.
Improve
monitoring of fish for methylmercury contamination
A major flaw in FDA's system is the
agency's own lack of comprehensive data on methylmercury in fish. In
January 2001, FDA recommended that pregnant women avoid consumption of king
mackerel based on methylmercury levels from a study published in 1979.
There are many other species where the data on methylmercury contamination
are similarly outdated, but where the available information indicates a
potential problem.
FDA must immediately expand its
methylmercury sampling program to include a host of fish where the data
indicate that pregnant women and their babies could receive a potentially
unsafe exposure from a relatively small amount of fish.
These
include:
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Sea bass
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Atlantic cod
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Grouper, black
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Orange roughy
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Bluefish
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Pacific cod
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Grouper, red
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Sand perch
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Bonito
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Pollock
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Red snapper
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White perch
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Porgy
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Yellowtail
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Rockfish
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Dover sole
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Halibut
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Lake trout
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Flounder, various
species
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Improve
public access to mercury contamination data
Consumers have a right to know about
contamination of the food supply, and FDA must be responsive to this right.
Currently they are not. EWG had great difficulty obtaining relatively
simple information about fish contamination from the agency through the
Freedom of Information Act. FDA currently posts the results of its Total
Diet Study on the web, and there is no reason that all of the agency's
mercury contamination information could not be posted as well.
Improve
risk assessments
FDA needs to move beyond its antiquated
and biologically implausible risk assessment methods based on average
people and average fish and adopt state-of-the-art risk assessment
techniques that provide a much more realistic picture of mercury exposure
and risk as it is distributed throughout the population.
It is not sufficient to protect the
population from average exposures when it is clear that many individuals
have far greater than average exposures for extended periods of time.
Reduce
Mercury Pollution at its Source
Mercury emissions from coal-fired power
plants, the largest man-made source of environmental mercury, are currently
completely unregulated. Federal decision-makers should require power plants
to reduce their mercury pollution by 90% and ultimately move away from
polluting sources of power.
Dr. Mercola's Comment:
The Environmental
Working Group is to be commended for their fine work in this area and
for providing an answer to a more definitive answer to a common question I
receive - "What are "safe" fish to eat?"
It is most unfortunate that the
mercury pollution from the coal plants has so contaminated the waterways
and the fish, as they are such a healthy food. One needs to be aware that
all fish are potentially contaminated with mercury. However I would revise
the EWGs list of safe fish by excluding the shellfish and fish without
scales and including a small safe fish, sardines. So here is my list of
safe fish:
Summer Flounder
Wild Pacific Salmon
Croaker
Sardines
Haddock
Tilapia
Not a very big list. It is important
to note that farmed fish are very similar to commercial beef. The fish are
fed grain products and the beneficial omega 3 fatty acids (EPA and DHA) are
totally distorted. Additionally, non-organic grain is used so the fish pick
up the pesticides that were used on the grains and also that run-off from
neighboring farmland.
So I would recommend limiting fish
consumption. There is another option that I will be discussing in about two
weeks which does "solve" the problem and allow you to obtain the
good nutrition of the fish while avoiding the mercury and pesticides.
Stay tuned.
Related
Articles:
National Academy of Science Backs Stricter
Mercury Standards
Toxic
Mercury Found in New England Rain and Snow
US EPA
Proposes Regulations to Cut Mercury Emissions From Coal-Fired Power Plants
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