OEHHA Releases Draft Advisory on Mercury in Fish in Lake Natoma and Lower American River

Apr 29, 2004

FOR IMMEDIATE RELEASE:
Release No.04- 03

CONTACT: Allan Hirsch
(916) 324-0955
www.oehha.ca.gov

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 from Lake Natoma and the lower American River in Sacramento County.

“The mercury in fish from Lake Natoma and the lower American River is a legacy of a century of gold mining activity in this region that began with the Gold Rush and continued into the 1950s,” OEHHA Director Dr. Joan Denton said. “The public should still enjoy fishing at these water bodies, but we recommend that people – especially women of childbearing age and children – carefully monitor how much fish they eat.”

OEHHA will hold a public workshop at 10 a.m. on May 10, 2004, to discuss and receive public comments on the draft evaluation and proposed advisory. The workshop will be held at the Cal/EPA Headquarters Building in the Coastal Hearing Room, Second Floor, 1001 “I” Street, Sacramento.. Written comments can be sent until June 2 to Dr. Robert K. Brodberg in 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 will then issue a final advisory. Until a final advisory is issued, OEHHA recommends that the public follow the advice in the draft advisory.

The draft advisory contains proposed guidelines for consumption of bass, channel catfish and other fish species from Lake Natoma and the lower American River between Nimbus Dam and Discovery Park. One set of proposals is for women of childbearing age and children age 17 and younger, who are particularly sensitive to methylmercury (the most prevalent form of mercury in fish). A second set of proposals is for women beyond their childbearing years and men.

The proposed guidelines call for women of childbearing age and children age 17 and younger to refrain from eating all channel catfish from these water bodies, while limiting consumption of all bass, white catfish, pikeminnow and sucker to one meal a month, and bluegill, sunfish and other species to one meal a week.
The proposed guidelines also call for women beyond childbearing years and adult men to limit their consumption of channel catfish and bass from these water bodies to one meal a month, white catfish, pikeminnow and sucker to one meal a week, and bluegill, sunfish and other species to three meals a week.

OEHHA’s evaluation and draft advisory are based on mercury analyses of fish samples from these water bodies by the U.S. Geological Survey, the University of California, Davis, and state and local monitoring programs.

Mercury in fish from these water bodies originated from gold-mining and dredging activity that took place from the Gold Rush until the 1950s. Miners used inorganic mercury to extract gold from mined materials and discharged the waste into rivers and streams, where mercury accumulated in the sediment. Bacteria converted 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 clearly 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.