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The Health
Effects From Eating Contaminated Fish
(back to Health Effects
page)
How do methyl mercury, dioxin and PCBs affect human health?
How do I reduce health risk?
What groups are most sensitive to contaminants?
What contaminants are in fish?
What is mercury?
How did mercury get into the West Virginia environment?
How does mercury get into fish?
Is mercury found in every type of fish?
Should I be concerned about exposure to mercury from eating fish?
Have fish in all West Virginia water bodies been tested for mercury?
Should I be concerned about exposure to mercury through swimming or other recreational activities in rivers, streams or lakes?
What are polychlorinated biphenyls (PCBs)?
What is dioxin?
What is dioxin used for?
Where did the dioxin come from?
How do people become exposed to dioxin?
Where can I learn more about dioxin?
What's being done about dioxin contamination?
What are future sampling plans?
What can I do if I am concerned about past fish consumption habits?
The Health
Effects From Eating Contaminated Fish
How do methyl mercury, selenium, dioxin and PCBs affect human
health?
The levels of
these compounds found in
West Virginia
fish are not known to cause immediate severe sickness. Long-lasting contaminants
such as PCBs, dioxin, selenium and mercury can build up in your body over time.
It may take months or years of regularly eating contaminated fish to build up
amounts that are a health concern. Health problems that may result from the
contaminants in fish range from small, hard to detect health changes to birth
defects, as well as mental and physical retardation in newborns. Mothers who eat
highly contaminated fish for many years before becoming pregnant may have
children who are slower to develop and learn. Therefore, women who plan to
become pregnant should follow the fish consumption advice given to pregnant and
nursing women for several years before becoming pregnant. It takes up to six
years or more for the body to get rid of PCBs, and up to one year to get rid of
mercury.
The advisories
that protect sensitive populations also protect all other members of the general
public.
How do I reduce health risk?
·
Eat smaller
fish (within the legal size limit). As a general rule, larger, older fish may be
more contaminated than smaller, younger fish.
·
Vary the
kind of fish you eat. Trout and sunfish, such as bluegill eat insects and other
aquatic life that are less likely to contain high levels of contaminants. Top
predators like bass and walleye may have higher levels of contaminants. If you
eat these species, eat the smaller fish to minimize your exposure.
·
Choose
leaner fish. Fish that are higher in fat –like channel catfish and carp – may
have higher levels of PCBs and other chemicals in their body fat. Yellow perch,
sunfish, and crappie are examples of lean fish.
·
Clean and
cook fish properly. How you clean and cook fish can reduce the level of
contaminants by as much as half in some fish. Some contaminants concentrate in
the fatty tissues and internal organs of fish. Filleting the fish, removing the
skin and internal organs, and trimming the fat along the back, side, and belly
of the fish helps reduce the contaminants. While cooking does not destroy
contaminants, heat from cooking melts some of the fat in fish and allows some of
the contaminated fat to drain away. Broil, grill, or bake the trimmed, skinned
fish on a rack so that the fat drips away. Deep-fat frying removes some of the
contaminants, but you should discard the oil after you cook the fish. Pan frying
does not remove much of the contaminants. Mercury levels cannot be reduced by
trimming because mercury binds to protein (the meat portion) of the fish.
What groups are most sensitive to contaminants?
Contaminants in
fish can be harmful to many people of all ages, but the fetus and young children
are especially sensitive to contaminants because their organs and systems are
not yet fully developed. They are less able than an adult is to deal with toxic
substances. Contaminants in fish can affect your baby more than they affect you
and can be hard to detect. It is best to prevent childhood exposure to fish
contaminants in the first place. In summary, the most sensitive groups are
unborn children and children age six and under. This advice also includes women
who plan to become pregnant, women who are pregnant and nursing mothers.
What contaminants are in fish?
The contaminants
responsible for the advisories within West Virginia are methyl mercury, PCBs,
selenium and dioxin. Other chemicals found in fish tissue have not been at levels where
a fish advisory is needed to protect the public’s health.
What is Mercury?
Mercury is
a naturally occurring metal found in the environment. Various compounds of
mercury have been used in medicine and industry. Although medicinal uses have
been discontinued, industrial uses of mercury continue
How did mercury get into the
West Virginia
environment?
Because mercury
is naturally occurring in the earths crust, natural land erosion may contribute
to releases of mercury into the environment. Inorganic mercury may enter the
air through burning of fossil fuels, mining, and waste or industrial emissions.
Mercury released into the air can travel long distances and be deposited on soil
and in waterbodies.
How does mercury get into fish?
In water bodies,
small organisms convert inorganic mercury to the organic form, methyl mercury.
Methyl mercury enters the aquatic food chain by binding with particles and
sediment eaten by fish. Large fish may prey on smaller mercury-contaminated
fish resulting in stored amounts of mercury in commonly caught fish. Fish
eliminate mercury at a very slow rate; therefore, mercury tends to accumulate in
their tissues and organs.
Is mercury found in every type of fish?
Mercury has been
detected in most fish species sampled from waterbodies in West Virginia and
other states. However, the range is quite broad and varies by water body and by
species of fish.
Should I be concerned about exposure to mercury from eating fish?
People who
consume moderate amounts of fish in a varied diet typically are not at risk of
exposure to high levels of mercury. However, mercury may cause damage to the
nervous system of an unborn child. Pregnant women who have high amounts of
mercury in their body pass some directly to the fetus. Because the effect
mercury has on the nervous system is so well documented and because the
developing fetus is highly sensitive, the West Virginia Bureau for Public Health
recommends that pregnant women, women of childbearing age, nursing mothers, and
children to follow both the West Virginia sport fish advisory recommendations
and the EPAs and FDA recommendation on restaurant and grocery-acquired fish. The
EPA and UFDA advisory follows.
Safety
regulations and advisories for fish in the market place are the responsibility
of the United States Federal Food and Drug Administration (FDA). Most kinds of
fish on the market are safe and the FDA encourages consumption of up to 12
ounces of fish per week.
The FDA and EPA
recently issued a joint advisory for women of childbearing age and children.
They recommend that women of childbearing age and children limit their intake of
fish, including store bought fish and tuna, to 2 to 3 meals per week (12 oz. of
fish per week for an adult woman). Children should eat less at each meal than
women of childbearing age. For more information about that advisory, see
http://www.fda.gov/bbs/topics/news/2004/NEW01038.html.
Based upon
national advisory information issued by FDA, the following species of fish could
pose health problems for nursing mothers and pregnant women. Avoid these kinds
of fish if you are concerned about your exposure to chemical contaminants:
Shark
Swordfish
King mackerel
Tilefish
Have fish in all
West Virginia water bodies been tested for mercury?
No. In order to
determine levels of contaminants biologists sample fish populations and collect
fish tissue for laboratory analysis. Recent analysis of fish tissue data for
West Virginia
streams indicate that mercury has accumulated in some fish in many streams and
lakes in West Virginia.
Should I be concerned about being exposed to mercury through
swimming or other recreational activities in rivers, streams or lakes?
No. In order to determine levels for
contaminants biologists sample fish populations and collect fish tissue for
laboratory analysis. Recent analysis of fish tissue data for
West Virginia streams indicate that mercury has accumulated in some fish in many
streams and lakes in
West Virginia.
What are polychlorinated biphenyls (PCBs)?
PCB is an
abbreviation for polychlorinated biphenyls. PCBs have good insulating and flame
retardant properties and were widely used as coolants and lubricators in
transformers, capacitors, and other electrical equipment. Manufacture of PCBs
was halted in the
US
in 1979 based on evidence that these compounds can be concentrated in the
environment and become a health hazard for humans. Although PCBs are no longer
manufactured, many old electrical transformers and capacitors still contain
them.
Experiments with
animals have demonstrated that PCBs can produce adverse health effects such as
liver damage, skin irritation, reproductive and developmental effects, and
cancer. It is prudent to assume that PCBs pose health hazards for humans as
well.
PCBs are
widespread and persistent in the environment. Consuming contaminated fish can be
a major exposure route for humans. Fish can accumulate PCBs through contaminated
water, sediment, and prey. PCBs tend to accumulate in the non-edible portions of
fish and in the fat.
What is dioxin?
The term
"dioxin" refers to a group of chemicals that share certain similar chemical
structures. This term is also used for the most well-studied and most toxic of
these compounds: 2,3,7,8-tetrachlorodibenzo-p-dioxin, or TCDD for short. Dioxins
are not created intentionally, but are a byproduct of human activities.
Combustion, chlorine bleaching of pulp and paper, some types of chemical
manufacturing and processing, and other industrial processes can create dioxin.
For additional
information concerning dioxin issues, contact the United States Environmental
Protection Agency (USEPA) at
www.epa.gov/ncea/dioxin.htm or contact
one of the state agencies.
What is dioxin used for?
Dioxins are
unwanted byproducts of human activities. Minute quantities are found in smoke
and ash from motor vehicles, municipal incinerators and wood fire. A September
1999 US EPA fact sheet lists pulp and paper bleaching processes and production
of some chlorinated phenols as sources. The most common source of dioxin
currently results from incineration. Dioxins have been found in soil, surface
water, sediment, plants, and animal tissue throughout the earth.
Where did the dioxin come from?
Past industrial
activities in the lower Kanawha Valley, especially near the city of
Nitro,
West Virginia, have resulted in several dioxin-contaminated sites. The dioxin
likely originated with the production of industrial solvents and the herbicide
2,4,5-T at facilities in and around Nitro. Disposal practices earlier in the
20th century --including burial of drums, dumping of dioxin-contaminated liquid
wastes, and incineration of dioxin-contaminated material-- spread dioxin
throughout the Nitro area. Areas downstream of Nitro likely became contaminated
through the release and transport of dioxin into the Kanawha River and its
tributaries. The Kanawha River and two of its tributaries, the Pocatalico River
and Armour Creek, have been the focus of a total maximum daily load (TMDL) study
and preliminary federal Superfund investigations to determine the location and
extent of the dioxin sources.
Sampling for
dioxin is continuing at several known and suspected contaminated sites in the
Nitro area.
How do people become exposed to dioxin?
Dioxin
accumulates in animal fat and tends to become concentrated in these tissues.
Dietary intake is the most common source of exposure to dioxin for the general
population. Meat, dairy products, fish, and other seafood contribute greater
than 90 percent of intake for the general population. People who consume large
quantities of freshwater fish and meats, dairy, and poultry products could have
higher dioxin exposure.
Where can I learn more about dioxin?
Informational
websites:
http://www.epa.gov/ncea/pdfs/dioxin/dioxreass.html
http://www.atsdr.cdc.gov/tfacts104.html
http://www.dep.state.pa.us/dep/deputate/polycomm/update/11-21-97/11219715.htm
Quotation or
citation of a published source should not be interpreted as an official
endorsement of that particular source. Sites quoted and cited are examples of
available reference materials. There is no actual or implied guarantee of their
accuracy.
What's being done about dioxin contamination?
The US EPA
continues to assess the extent and magnitude of dioxin contamination in the
Nitro area. In March 2004, USEPA entered into an administrative order to conduct
an Engineering Evaluation/Cost Analysis to study dioxin-contaminated sediment in
the Kanawha
River. The purpose of this is to evaluate response alternatives that would
protect public health, welfare, and the environment and to provide sufficient
information for USEPA to determine the necessity, feasibility, and effectiveness
of particular non-time critical removal actions. This effort is coordinating
with the sport fish advisory committee in the development of a fish consumption
survey and additional fish sampling.
What is
selenium?
Selenium is a
naturally occurring mineral element that is distributed widely in nature in most
rocks and soils, particularly in the western and southwestern United States.
What are
the sources and uses of selenium?
Most processed
selenium is used in the electronics and glass industries. Selenium is a
component of pigments in plastics, paints, enamels, inks, and rubber. Selenium
is used in the preparation of pharmaceuticals, pesticides, and rubber. Selenium
is an ingredient in some anti-dandruff shampoos. Selenium can be released into
the environment during combustion of fossil fuels, and when metals are smelted.
It is present in leachate from coal fly ash disposal areas. In West
Virginia selenium has been found downstream of large-scale earth disturbance
activities. Selenium also enters the environment when rocks weather.
What are the health effects of selenium?
Selenium is an
essential nutrient but is toxic to both humans and animals at high
concentrations. Selenium is used as a nutritional supplement for humans and
animals. Long-term adverse effects from ingestion by humans have not been
studied thoroughly. Selenium has the ability to bioaccumulate in aquatic food
chains and may thereby contaminate the diet and induce reproductive effects in
fish and birds. EPA has determined that one specific form of selenium, selenium
sulfide, is a probable human carcinogen. However, selenium sulfide is not
present in foods or the environment.
Where can I learn more about selenium?
Informational
websites:
http://www.atsdr.cdc.gov/tfacts92.html
http://www.epa.gov/safewater/dwh/c-ioc/selenium.html
Quotation or
citation of a published source should not be interpreted as an official
endorsement of that particular source. Sites quoted and cited are examples of
available reference materials. There is no actual or implied guarantee of their
accuracy.
What are future sampling plans?
Fish
contamination is a measure of environmental health as well as a potential source
of human illness. BPH, DNR, and DEP are striving to improve the understanding of
fish contamination throughout West Virginia. In 2001 DEP secured a grant from
the EPA to conduct a two-year statewide evaluation of fish for PCB and mercury
contamination. DEP, DNR, BPH and the West Virginia University/US
Geological Survey Cooperative Fish and Wildlife Research Unit conducted this
research. The study was finalized in 2004 and supplied the basis for the
2005 Fish Consumption Advisories.
DEP is continuing to analyze
available fish tissue for selected contaminants when funding is available.
What can I do if I am concerned about past fish consumption habits?
You should
discuss any health concerns with your health care provider. The Bureau for
Public Health can provide additional information.
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