OEHHA Seeks Comments on Draft Advisory on Mercury in Fish in Bear River, South Yuba River, Deer Creek Watersheds

Jan 31, 2003

FOR IMMEDIATE RELEASE: Release No. 03-01
CONTACT: Allan Hirsch (916) 324-0955

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 certain fish from five reservoirs and portions of the Bear and South Yuba rivers and Deer Creek in Nevada, Placer and Yuba counties.

Once finalized, the fish advisory will be the first ever issued by the State of California for water bodies in the Sierra Nevada.

"We are using 21st-century science to evaluate potential health threats from eating fish containing mercury that was released into Sierra streams as far back as the Gold Rush," OEHHA Director Dr. Joan Denton said. "In most cases, limited amounts of fish can be eaten safely, but we recommend that people - especially females of childbearing age and children - carefully monitor how much they eat."

A draft report containing the proposed advisory and OEHHA's evaluation of potential health threats posed by mercury in the fish is available for viewing. OEHHA will hold a public workshop in Grass Valley at 2 p.m. on February 27, 2003, to discuss and receive public comments on the draft evaluation and proposed advisory. The workshop will be held at the Nevada Irrigation District Conference Room, 1036 West Main Street. Written comments can be sent until February 27 to OEHHA's Pesticide and Environmental Toxicology Section, P.O. Box 4010, Sacramento, CA 95812-0410.

The draft advisory contains proposed guidelines for consumption of bass, channel catfish and other fish species from Camp Far West Reservoir, Lake Combie, Lake Englebright, Rollins Reservoir, Scotts Flat Reservoir and portions of the South Yuba River, Deer Creek and Bear River. One set of proposals is for females 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 adult males and females beyond their childbearing years.

The proposed guidelines call for females of childbearing age and children to refrain from eating all bass from Camp Far West Reservoir; limit their consumption of bass and channel catfish from the other water bodies to 1 to 2 meals per month, depending on where the fish were caught; and limit their consumption of trout from Deer Creek to 2 meals per month. The proposed guidelines also call for females beyond childbearing years and adult males to limit their consumption of bass and channel catfish to 2 to 4 meals per month, depending on where the fish were caught; and limit consumption of Deer Creek trout to 4 meals per month.

OEHHA's evaluation and draft advisory are based on fish samples from the five reservoirs and 14 stream sites in the watersheds taken by the U.S. Geological Survey (USGS) in 1999. OEHHA completed an initial analysis of the sampling results in 2000 and assisted local health offices in Nevada, Placer and Yuba counties in developing interim health advisories that recommend adults and children limit their consumption of bass species to 1 meal per month, and channel catfish and various other species to 1 meal per week. The OEHHA draft fish advisory is based on a more extensive evaluation of the USGS data and will replace the interim county advisories when it is finalized.

Mercury in fish from these watersheds is a legacy of gold mining dating from the Gold Rush. Miners used inorganic mercury to extract gold from mined materials and discharged the waste into 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.