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By Archana Malla
Mercury and polychlorinated biphenyls
(PCBs) are toxic chemicals
present in the environment in different forms:
- Airborn mercury is found in its elemental form, whereas waterborn
mercury is present as methyl mercury, which is more toxic than
elemental mercury. Although
mercury in the environment comes from the improper disposal of mercury
products and wastewater discharges, most of it comes from coal
burning power plants.
Almost all of these plants in Ohio are old. These aging plants emit excess
mercury and thus pollute the air and water of Ohio.
- PCBs were found in many products including dielectric fluids
in transformers and capacitors, coolants, lubricants, pesticide
extenders, flame retardants,
hydraulic fluids, adhesives, wood floor finishes, and in carbonless copy
paper. PCB production was banned in the 1977 due to its harmful
health effects. PCBs
are classified as persistent organic pollutants which bioaccumulate in
animals. PCBs can still be released into the environment from
hazardous waste sites,
by the illegal or improper disposal of industrial wastes and consumer
products, from leaks from old electrical transformers containing
PCBs, and by the burning
of some wastes in incinerators. PCBs do not readily break down in the
environment and thus may remain there for very long periods of
time. In water, a small
amount of PCBs may remain dissolved, but most stick to organic particles
and bottom sediments. These toxic chemicals in water resources
get into the tissue
of fish and then transfer to the human body through the food chain.
 Human exposure to methyl mercury is a global concern. Mercury poses
greater risk to children, women of childbearing age, pregnant
women, and nursing mothers. Small amounts of mercury can damage
the brain and nervous system of a fetus, infant, or young child,
which may lead to impairment in learning, memory, vision, and
hearing. The EPA has recently estimated that about 400,000 babies
born each year in the U.S. are at risk of neurological damage
due to the consumption of mercury-contaminated fish. Other health
risks associated with mercury exposure are various neurological
disorders such as tremors, vision change, loss of hearing, muscle
coordination, loss of sensation, and difficulties with memories.
Higher exposure to mercury can affect the kidneys, lungs, and
digestive and cardiovascular systems. Health problems associated
with PCBs include damage to the nervous and immune systems in
children, and skin conditions in adults. Women who ate large
amounts of fish contaminated with PCBs had babies that weighed
slightly less than babies from women who did not have these exposures.
Babies born to women who ate PCB-contaminated fish have abnormal
responses such as problems with motor skills and a decrease in
short-term memory. A study suggests that the immune system was
affected in children born to and nursed by mothers exposed to
increased levels of PCBs. A few studies of workers indicate that
PCBs were associated with certain kinds of cancer in humans,
such as cancer of the liver and biliary tract.
Fish and shellfish are a good part of a healthy low-fat diet and are a great source
of protein, vitamins, and minerals. However,
you could be harmed by eating certain types of fish or by eating
too many fish too often from waters high in mercury and PCBs contamination.
All ages, regardless of gender and ethnicity, are affected though
the level of risk varies on concentration and duration of exposure.
 Ohio
has been issuing fish consumption advisories for 15 years to make
people aware of safe fish varieties and safe fish portions
to avoid risk to consumers. They are not enforceable limits, but
act as guidelines and suggestions on what is considered safe meal
size, safe meal frequency, and what species are reliable for consumption.
Also, they are not intended to discourage anyone from eating fish
but should be used as a guide for choosing fish with low contaminants.
Fish consumption advisories are issued by the state, tribal, and
local governments to communicate the risk associated with certain
chemicals in certain water bodies. The Ohio EPA with the help of
the Ohio Department of Health and the Ohio Department of Natural
Resources issue an updated annual fish consumption advisory on
the basis of processed samples collected during the previous fishing
season. Since fishing season has begun, they already have issued
the la test 2008 advisory from 391 collected samples. The fish
consumption advisory has been improved for some species in Lake
Erie and the Ohio River. Lake Erie walleye 23 inches and larger
can now be eaten once a week instead of a one-meal-a-month limit.
Lake Erie channel catfish 16 inches and over also can be eaten
at one meal every two months which have been upgraded from ‘do
not eat’. Similarly, flathead catfish 20 inches and over
and smallmouth buffalo 24 inches and over from the Ohio River have
changed from one meal every two months to one meal per month. More
stringent advisories are required for some species in the study
of water bodies such as Dow Lake, East Fork Lake, Lake Erie, Little
Miami River, Mahoning River Muskingum River, Ohio River, and West
Branch Reservoir. Due to mercury concentration, a statewide advisory
of one meal per week for most fish remains the same.
Fish from the
ocean, estuaries, and inland water also may contain certain amount
of mercury and PCBs as well as other contaminants.
The amount of contaminants that may be present in commercially
available fish can add to the fish what you are already taking
in from other sport fish. You should consider all sources
of fish in your diet while making choices of eating sport fish. Fish present
in grocery stores, restaurants, and food stores are subject to
inspection and regulation. Fish with levels of contaminants above
the Food and Drug Administration levels of concern are not allowed
in the market.
There are several ways to lower the health hazard
from harmful contaminant. Choosing a variety of smaller and younger
fish, and
seafood caught in different places can reduce the risk of contamination.
As harmful chemicals build up in the fatty parts of fish, trimming
off the skin, belly fat, and other fat when preparing fish will
help to reduce PCB contamination. More details on all fish advisories
issued in Ohio can be found by visiting Ohio EPA’s Web site
http://www.epa.state.oh.us/dsw/fishadvisory/index.html.
There is more information available at www.earthdaycoalition.org.
Archana
Malla is working on Ohio’s Fish Consumption Advisory
at Earth Day Coalition. |
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