[env-trinity] More Trinity lake Mercury Info from the Office of Environmental Health Hazard Assessment

[Josh Allen]

Release No. 05- 03
April 8, 2005
OEHHA Releases Draft Advisory on Mercury in Fish in Trinity Lake and
Other Water Bodies in the Trinity River Watershed

Contact: Allan Hirsch
(916) 324-0995 

SACRAMENTO -- The California Environmental Protection Agency's Office of
Environmental Health Hazard Assessment (OEHHA) is seeking public
comments on a draft fish advisory concerning elevated levels of mercury
in fish in Trinity Lake and selected water bodies in the Trinity River
watershed in Trinity County.
<http://www.oehha.ca.gov/fish/so_cal/trinitycrnr.html>  

"The pristine ambience of Trinity County does not change the fact that
mercury from past mining activities and other sources was released into
the region's waterways, and has accumulated in the fish," OEHHA Director
Dr. Joan Denton said. "The public should still enjoy fishing in the
Trinity River watershed, but we recommend that people - especially women
of childbearing age and children - carefully monitor how much fish they
eat." 

A fact sheet and draft report
<http://www.oehha.ca.gov/fish/so_cal/TrinRiverF.html>  containing the
proposed advisory and OEHHA's evaluation of potential health threats in
the fish posed by methylmercury (the most prevalent and toxic form of
mercury in fish) are available for viewing and downloading on OEHHA's
Web site at www.oehha.ca.gov <http://www.oehha.ca.gov/> . 

OEHHA staff scientists will make a presentation, answer questions and
accept public comments on the draft advisory at a public workshop at
11:30 a.m. on May 3, 2005, at the Victorian Inn Conference Room, 1709
Main Street, Weaverville, California. 

Written comments on the draft advisory can be sent until May 9, 2005, to
OEHHA's Pesticide and Environmental Toxicology Section, P.O. Box 4010,
Sacramento, CA 95812-4010. OEHHA will review all comments, make any
appropriate revisions and issue a final advisory. 

The draft advisory contains proposed guidelines for consumption of fish
from the following Trinity County water bodies: Trinity Lake (also known
as Clair Engle Lake), the Trinity River, Lewiston Lake, Coffee Creek,
Canyon Creek, Eastman Creek, Eastman Dredge Ponds, Carrville Pond, Crow
Creek, Tamarack Creek, the New River and the East Fork Trinity River and
its tributaries. 

One set of proposed guidelines is for women of childbearing age and
children age 17 and younger, who are particularly sensitive to
methylmercury. A second set of proposed guidelines is for women beyond
their childbearing years and men. Until a final advisory is issued,
OEHHA recommends that the public follow the advice in the draft
advisory. This replaces the interim county advisory
<http://www.oehha.ca.gov/fish/so_cal/TrinRiver.html>  issued in July
2002. 

The draft advisory contains the following recommendations for women of
childbearing age and children age 17 and under: 

*	Limit consumption of all bass from all water bodies named above
to one meal a month, and also consumption of Chinook (king) salmon from
Trinity Lake, and rivers and creeks draining into the lake, to one meal
a month. With the exception of trout from Lewiston Lake and Carrville
Pond, consumption of all other sport fish species, including white
catfish from all water bodies and trout from any other water body,
should be limited to one meal a week. The one-meal-a-week recommendation
also applies to salmon from rivers and creeks below Lewiston Lake. Trout
from Lewiston Lake and Carrville Pond may be consumed up to three times
per week for this population group. 

The draft advisory contains the following recommendations for women
beyond childbearing years and men: 

*	Limit consumption of all bass from the water bodies named above
to one meal a week, and also consumption of Chinook (king) salmon from
Trinity Lake, and rivers and creeks draining into the lake, to one meal
a week. Consumption of all other sport fish species, including white
catfish and trout, should be limited to three meals a week. The
three-meal-a-week recommendation also applies to salmon from rivers and
creeks below Lewiston Lake. 

The draft advisory incorporates the results of fish sampling conducted
recently in the Trinity River watershed by the U.S. Geological Survey
and the State Water Resources Control Board. 

Mercury in fish from the Trinity River watershed originated from the
mining of mercury and gold, the majority of which took place from the
Gold Rush until approximately 1960. Miners used mercury to extract gold
from mined materials and discharged the waste into rivers and streams,
where mercury accumulated in the sediment. Bacteria converted the
mercury to the more toxic methylmercury, which fish take in from their
diet. Methylmercury can accumulate in fish to concentrations many
thousands of times greater than mercury levels in the surrounding water.


After entering rivers, streams, and estuaries, mercury accumulates in
the sediment. Bacteria convert the inorganic mercury to the more toxic
methylmercury, which fish take in from their diet. Methylmercury can
accumulate in fish to concentrations many thousands of times greater
than mercury levels in the surrounding water. 

Women can pass methylmercury on to their fetuses through the placenta,
and to infants through breast milk. Excessive exposure to methylmercury
may affect the nervous system in children, leading to subtle decreases
in learning ability, language skills, attention and/or memory. These
effects may occur through adolescence as the nervous system continues to
develop. In adults, the most subtle symptoms associated with
methylmercury toxicity are numbness or tingling sensations in the hands
and feet or around the mouth. Other symptoms at higher levels of
exposure could include loss of coordination and vision problems. 

The Office of Environmental Health Hazard Assessment is one of six
entities within the California Environmental Protection Agency. OEHHA's
mission is to protect and enhance public health and the environment by
objective scientific evaluation of risks posed by hazardous substances.

Draft Health Advisory for Fish from Trinity Lake and Selected Water
Bodies In the Trinity River Watershed (Trinity County)

A Fact Sheet

 

[04/08/05]





  _____  

Why has OEHHA developed a draft health advisory for fish from Trinity
Lake and selected water bodies in the Trinity River Watershed?

Recent studies by the U.S. Geological Survey and the State Water
Resources Control Board indicated that some species of fish in Trinity
Lake and other water bodies in the Trinity River watershed contain
elevated levels of mercury and could pose a health risk to people who
eat them frequently. The Office of Environmental Health Hazard
Assessment (OEHHA) has evaluated the health effects of eating fish from
Trinity Lake (also known as Clair Engle Lake), the Trinity River,
Lewiston Lake, Coffee Creek, Canyon Creek, Eastman Creek, Eastman Dredge
Ponds, Carrville Pond, Crow Creek, Tamarack Creek, the New River, and
the East Fork Trinity River and its tributaries and has issued a draft
report <http://www.oehha.ca.gov/fish/so_cal/trinitycrnr.html>  and
health advisory with guidelines for the consumption of fish from these
water bodies. 

OEHHA recommends that individuals limit their consumption of bass,
Chinook (King) salmon, white catfish, and other types of fish from
Trinity Lake and other listed water bodies in the Trinity River
watershed. One set of guidelines applies to women of childbearing age
and children age 17 and younger, who are particularly sensitive to
methylmercury (the most prevalent and toxic form of mercury in fish). A
second set applies to women beyond their childbearing years and men. 

Why is mercury found in fish from this region?

Mercury contamination of fish is a global problem. Emissions from
volcanoes and coal-burning power plants release mercury into the air
where it can be carried worldwide before being deposited in oceans,
lakes, and rivers. In northern California water bodies, however, mercury
is also a legacy of gold and mercury mining activities that began during
the Gold Rush and continued until approximately 1960. Both gold and
mercury were mined in the Trinity River watershed and some mercury
remains today. The inactive Altoona Mercury Mine is located along the
East Fork Trinity River and is reported to contribute significantly to
the mercury content of Trinity Lake. Gold miners used mercury to extract
gold from mined materials and discharged the waste into streams, where
the mercury accumulated in the sediment. Liquid mercury moves relatively
slowly through river systems and accumulates in places where sediments
are trapped, such as reservoirs. Bacteria convert this inorganic form of
mercury into a more toxic, organic form, known as methylmercury, which
fish take in from their diet. Methylmercury can accumulate in fish to
concentrations many thousands of times greater than mercury levels in
the surrounding water. Because methylmercury accumulates in fish slowly
over time, larger fish of a species usually have higher concentrations
of methylmercury than smaller fish from the same water body. Predatory
fish, such as bass, generally contain more methylmercury than
non-predatory fish, such as trout. 

What are the human health effects of methylmercury found in these fish? 

Developing fetuses and children are especially sensitive to
methylmercury. Pregnant women and nursing mothers can pass on
methylmercury to their fetuses or infants through the placenta and
through breast milk. Excessive exposure to methylmercury can affect the
nervous system in children, leading to subtle decreases in learning
ability, language skills, attention, and memory. These effects may occur
through adolescence as the nervous system continues to develop. For this
reason, a more conservative set of guidelines applies to women of
childbearing years and children up to and including age 17. 

In adults, the most subtle symptoms of methylmercury toxicity are
numbness and tingling sensations in the hands and feet or around the
mouth. Other symptoms at higher levels of exposure could include loss of
coordination and vision problems. 

The levels of methylmercury found in fish from these lakes and rivers
should not result in the health effects described above if the proposed
guidelines are followed. The extent of health effects depends on the
amount of methylmercury that people ingest from the fish that they eat
and is also related to a person's body weight. 

What are the next steps in OEHHA's evaluation?

OEHHA is seeking public comment on the draft report and advisory
guidelines. OEHHA staff scientists will make a presentation, answer
questions and accept comments on the draft advisory at a public workshop
at 11:30 a.m. on May 3, 2005, at the Victorian Inn Conference Room, 1709
Main Street, Weaverville, California. Written comments can also be sent
directly to OEHHA at the address below until May 9, 2005. OEHHA will
review all comments before issuing a final report and advisory. 

Should I stop eating all fish from these water bodies?

No. Fish are a nutritious part of your diet when eaten in moderate
amounts. By following OEHHA's guidelines for eating fish from this
region, you can reduce your risk of health effects from exposure to
methylmercury. 

Because of the increased sensitivity to methylmercury during periods of
neurological development, it is particularly important for women of
childbearing age and children age 17 and younger to follow the guidance
provided. OEHHA offers separate advice for women beyond their
childbearing years and adult men. 

Additionally, because virtually all ocean and freshwater fish contain
some level of methylmercury, OEHHA recommends that women of childbearing
age and children aged 17 and younger do not eat shark, swordfish, king
mackerel, or tilefish and limit their total consumption of any locally
caught sport fish to no more than one meal per week, unless more
restrictive advice is already in place. This advice is consistent with
recent federal guidance for consumption of commercial and sport fish. 

Where can I get more information?

For information on mercury and other contaminants in sport fish in
California, contact: 

Office of Environmental Health Hazard Assessment
Pesticide and Environmental Toxicology Section
P.O. Box 4010
Sacramento, CA 95812-4010 

(916) 327-7319 or http://www.oehha.ca.gov <http://www.oehha.ca.gov/> 

For information on mercury in commercial fish, contact: 

U. S. Food and Drug Administration
Center for Food Safety and Applied Nutrition
1 (888) SAFEFOOD or http://www.cfsan.fda.gov <http://www.cfsan.fda.gov/>


Address written comments to: 

Dr. Robert Brodberg
Office of Environmental Health Hazard Assessment
Pesticide and Environmental Toxicology Section
P.O. Box 4010
Sacramento, CA 95812-4010

  _____  

Draft Health Advisory for Fish from Trinity Lake and Selected Water
Bodies in the Trinity River Watershed (including Trinity River, Lewiston
Lake, Coffee Creek, Canyon Creek, Eastman Creek, Eastman Dredge Ponds,
Carrville Pond, Crow Creek, Tamarack Creek, the New River, and the East
Fork Trinity River and its tributaries)

Fish Consumption Guidelines*

Type of Fish

Women of childbearing age and children age 17 and younger 

Eat No More Than:

Women beyond childbearing years and men 

Eat No More Than:

All Sites, Except Specific Species at Sites Listed Below

 

 

All Bass

Once a Month

Once a Week

Chinook (King) Salmon

Once a Week

3 Times a Week

White Catfish

Once a Week

3 Times a Week

All Trout

Once a Week

3 Times a Week

Other Sport Fish Species including salmon from rivers and creeks below
Lewiston Lake

Once a Week

3 Times a Week

Trinity Lake (including rivers and creeks draining into Trinity Lake)

 

Chinook (King) Salmon

Once a Month

Once a Week

Lewiston Lake and Carrville Pond

 

 

All Trout

3 Times a Week

3 Times a Week

 

 

 

 

				

*MANY OTHER WATER BODIES ARE KNOWN OR SUSPECTED TO HAVE ELEVATED MERCURY
LEVELS. If guidelines are not already in place for the water body where
you fish, women of childbearing age and children aged 17 and younger
should eat no more than one sport fish meal per week and women beyond
childbearing age and men should eat no more than three sport fish meals
per week from any location. 

EAT SMALLER FISH OF LEGAL SIZE. Fish accumulate mercury as they grow. 

DO NOT COMBINE FISH CONSUMPTION ADVICE. If you eat multiple species or
catch fish from more than one area, the recommended guidelines for
different species and locations should not be combined. For example, if
you eat a meal of fish from the one meal per month category, you should
not eat another fish species containing mercury for at least one month. 

SERVE SMALLER MEALS TO CHILDREN. MEAL SIZE IS ASSUMED TO BE 8 OUNCES FOR
A 160-POUND ADULT. If you weigh more or less than 160 pounds, add or
subtract 1 oz to your meal size, respectively, for each 20-pound
difference in body weight. 

 

 

 

 

 

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