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

Sep 2, 2004

FOR IMMEDIATE RELEASE: Release No. 04-06
CONTACT: Allan Hirsch (916) 324-0955

SACRAMENTO -- The California Environmental Protection Agency’s Office of Environmental Health Hazard Assessment (OEHHA) has finalized a fish advisory concerning elevated levels of mercury in fish from Lake Natoma and the Lower American River in Sacramento County.

“Fish are still recommended as part of a healthy, balanced diet. But anglers and their families – especially women of childbearing age and children – should be aware of the presence of mercury in fish from Lake Natoma and the lower American River, and follow our guidelines for safe consumption of these fish,” OEHHA Director Dr. Joan Denton said.

A report containing the advisory and OEHHA’s evaluation of potential health threats posed by mercury in the fish is available for viewing and downloading on OEHHA’s Web site.

The advisory contains guidelines for consumption of bass, channel catfish and other fish species from Lake Natoma, the lower American River between Nimbus Dam and Discovery Park, and nearby creeks and ponds. 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 and toxic form of mercury in fish). A second set of proposals is for women beyond their childbearing years and men.

The 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 guidelines also call for women beyond childbearing years and 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 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 new advisory contains the same consumption guidelines as an earlier draft advisory that OEHHA released for public review and comment in April 2004. Visit oehha.ca.gov to view the fish advisory guidelines, reports, and fact sheets for Lake Natoma and the Lower American River.