Why has Illinois issued a statewide methyl mercury advisory?
Illinois Fish Contaminant Monitoring Program (IFCMP)*
has issued a statewide advisory for predator species in Illinois
waters. The change is based on the latest scientific findings of recent
studies that have documented impaired fetal development and a consistent
pattern of methyl mercury levels detected in predator species throughout
the state. The advisory has been established to protect the most sensitive
populations including pregnant or nursing women, women of child-bearing
age, and children <15 years of age.
*IFCMP includes staff from the Departments’ of Agriculture,
IEPA, DNR, IDPH, and Nuclear Safety.
Q: Has the concentration of mercury increased in Illinois predator
A: No. Methyl mercury levels detected in predator sport fish have remained
relatively consistent; the advisory has been issued based on the results
of recent scientific studies indicating that methyl mercury is more
toxic than previously thought. Based on the study results, the guidelines
that were used to establish the Illinois fish advisories have been lowered
for methyl mercury.
Q: Why is the statewide methyl mercury advisory only for predator
is very persistent in the environment. Small organisms absorb mercury
from water and sediment and the organisms are eaten by smaller fish.
Predator fish eat the smaller fish and methyl mercury is accumulated
up the food chain so the larger fish have the highest amounts of methyl
mercury stored in their bodies. Predator
species for Illinois include all species of black bass (largemouth,
smallmouth, and spotted), striped bass, white bass, hybrid bass, walleye,
sauger, saugeye, flathead catfish, muskellunge, and northern pike.
Is mercury stored in the human body for long periods of time?
A: When methyl mercury is ingested, approximately 95% is absorbed through
the gastrointestinal tract into the bloodstream and it is rapidly carried
to other parts of the body. The half-life for methyl mercury in the
body is approximately 70 days. It is slowly excreted from the body over
several months, mainly in feces.
Q: Why is there a special methyl mercury advisory for pregnant
or nursing women, women of child-bearing age, and children <15 years
are the populations at highest risk for adverse health effects. This
is due to the greater sensitivity of the developing nervous system of
infants and children.
How does methyl
mercury get into water bodies in Illinois?
A: Mercury is a metal that occurs naturally in small amounts in the
environment. It also is thought to come from burning coal or trash,
as well as from industry. Mercury gets into lakes and rivers several
ways, including rain and runoff. When conditions are right in the water,
certain kinds of bacteria change inorganic mercury into methyl mercury.
Methyl mercury is stored in the muscle of fish that eat mercury-contaminated
food or live in mercury-contaminated water.
Q: What are the potential health effects for people who eat fish
contaminated with methyl?
At low doses, methyl mercury can harm the developing nervous
system in a fetus and children. At high doses, methyl mercury can affect
the central nervous system (triggering such health problems as memory
loss and slurred speech), kidney damage and failure, and gastrointestinal
damage. The health affect is dependent on the amount of methyl mercury
in the fish and how much is consumed over a period of time. Based
on the concentrations detected in predator sport fish in Illinois, it
is unlikely that individuals would experience health effects associated
with high doses.
Q: What about the fish I buy in the grocery store - do I have
to be concerned that they may be contaminated with mercury?
such as shark, swordfish, king mackerel, and tilefish contain high
levels of methyl mercury. The FDA is advising pregnant women, women
of child-bearing age, and children not to eat these fish. The FDA
advisory acknowledges that seafood can be an important part of a balanced
diet for pregnant women and those of child-bearing age who may become
pregnant. FDA advises these women to select a variety of other kinds
of fish including shellfish, canned fish (including
tuna), smaller ocean fish or farm-raised fish. These women
can safely eat 12 ounces per week of cooked fish. A typical serving
size of fish is from 3 to 6 ounces.
Q: Why has Illinois issued a statewide methyl mercury advisory
based on a new standard, but at the same time lowered the advisory for
Cedar Lake and Lake Kinkaid? Has the concentration of mercury decreased
in these lakes and in the sport fish?
A:The concentration of methyl mercury in predator sport fish in Cedar
and KinkaidLakes has not changed
significantly. A new approach for issuing fish advisories for methyl
mercury in Illinois has changed
significantly. Prior to this year’s fish advisory, advisories
for methyl mercury were based solely on protecting sensitive populations
and there were only two categories: “do not eat” and “unrestricted”.
The new approach for issuing fish advisories for methyl mercury has
resulted in five categories (similar to the PCB approach) and the added
categories include advisories for sensitive populations as well as men
(>15 years) and women beyond child-bearing age.
I be concerned about children swimming in water bodies in Illinois based
on mercury contamination?
A: No. The amount of contact or incidental
consumption you would experience while swimming in waters contaminated
with mercury is insignificant.
there a Special Mercury Advisory for some water bodies in the state?
A: Laboratory results from predator sport fish in
some water bodies (Ohio River, Campus Lake, Cedar Lake, and Kinkaid
Lake) have shown higher contamination than what has typically been found
in other water bodies. Based on these higher concentrations of methyl
mercury, a more restrictive advisory is necessary to protect public
Q : Why are there so many new advisories based on PCBs this
IFCMP is a source of federal funds that paid for the analyses of fish
samples was reduced in 1992 and 1993, and disappeared from 1994-1996.
Therefore, there is a fairly large gap in the database used by the
IFCMP to determine the need for advisories. Beginning in 1997, state
funds became available to pay for the fish analyses, and the IFCMP
began filling in the data gaps. Since in most cases two consecutive
samples are needed to add, change, or remove an advisory, it wasn’
t until 1999 that changes could start to occur in the advisory list.
A large number of waters that were identified as needing a second
sampling from 1997-1999 had the required follow-up sampling completed
last year, which is why there are 21 new bodies of water listed for
PCB contamination, and a major revision of the advisory for the Rock
River this year.
actions are being taken to reduce man-made sources of mercury into
are several actions being taken, at the national, regional, state,
and local level. At the national level, USEPA is developing Maximum
Achievable Control Technology (MACT) standards for air pollution sources
that emit mercury, which should be released soon. It is also working
on regulations or guidance on air pollution controls to limit the
amount of mercury emitted from coal-burning power plants, which have
been identified as significant sources of airborne mercury. At the
regional level, the US-Canadian Binational Toxics Strategy has developed
numerous approaches for voluntary reductions in mercury releases to
the environment, some of which are already being implemented in the
Great Lakes basin (ex., fluorescent bulb recycling programs, mercury
thermometer exchange programs). At the state level, the IEPA has formed
a mercury workgroup to research sources of mercury release to the
air in Illinois, and to identify opportunities for mercury reductions
through regulations and air permits (these efforts will require the
final release of the MACT standards before they can be implemented).
The IEPA has also obtained a grant from the USEPA' s Great Lakes National
Program Office to investigate ways to decrease the use of mercury
in hospitals, which has resulted so far in a pilot program for mercury
thermometer exchanges at two hospitals. At a more local level, there
are a few fluorescent lamp recycling programs in existence (a listing
can be found at
and elemental mercury and mercury-containing products can be turned
in at Household Hazardous Waste collections sponsored by IEPA each