OEHHA Releases Draft Advisories on Mercury in Fish in Lake Sonoma and Lake Mendocino

Aug 17, 2006

FOR IMMEDIATE RELEASE:
Release No. 06- 06
August 17, 2006

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 draft fish advisories concerning elevated levels of mercury in some fish in Lake Sonoma (Sonoma County) and Lake Mendocino (Mendocino County).

“Like many water bodies in the California Coast Ranges, Lake Sonoma and Lake Mendocino are located near areas rich in mercury ores that had been mined in the past. So it is not surprising that some fish in these lakes have elevated mercury levels,” OEHHA Director Dr. Joan Denton said. “People can still enjoy eating the fish they catch from these lakes if they choose species that are lower in mercury and eat them in moderation.”

Sonoma County Health Officer Dr. Mary Maddux-Gonzalez said, "It is particularly important that pregnant and nursing mothers and children limit their exposure to mercury due to the toxic effects that this element can have on brain development. These guidelines developed by the State provide practical information for individuals and families to make healthy choices in limiting their exposure to mercury from fish in Lake Sonoma and other water bodies." Dr. Maddux-Gonzalez can be reached for comment at (707) 565-4401.

OEHHA staff scientists will make a presentation, answer questions and accept public comments on the draft advisories at a public workshop to be held at 5 p.m. on September 19, 2006, at the North Coast Regional Water Quality Control Board office, 5550 Skylane Blvd., Suite A, Santa Rosa.

Written comments on the draft advisories must be received by 5 p.m. on October 2, 2006, at OEHHA’s Pesticide and Environmental Toxicology Branch, 1515 Clay Street, 16th floor, Oakland, CA 94612. OEHHA will review all comments, make any appropriate revisions and issue final advisories.

For both Lake Sonoma and Lake Mendocino, the draft safe-eating guidelines recommend that women of childbearing age and children 17 years and younger may eat up to one meal a week of sunfish or crappie. They should eat no more than one meal a month of largemouth or smallmouth bass (and only if no other fish are eaten). Women beyond childbearing years and men may eat up to two meals a week of sunfish or crappie, or one meal a week of largemouth or smallmouth bass.

The draft advisories incorporate the results of fish sampling conducted by the North Coast Regional Water Quality Control Board.

The watershed draining into the two lakes is rich in mineral deposits, and prospecting for mercury has taken place in the area since the mid-1800s. Mercury from natural weathering and mining waste is believed to have entered the area’s water bodies. The region’s geothermal springs also vent mercury into water bodies. Mercury accumulates in the sediment and is converted by bacteria 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. Physical contact with the water in the lakes is safe.

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.

Fish are an important part of a balanced diet, and the American Heart Association recommends the consumption of two meals a week of fish that are low in mercury, such as shrimp, king crab, scallops, farmed catfish, wild ocean salmon, oysters, tilapia, flounder and sole. To maximize the health benefits of fish consumption, OEHHA recommends that people choose fish with lower levels of mercury that can be eaten most frequently. Because virtually all fish contain some level of mercury, people consuming the maximum amount of Lake Sonoma and Lake Mendocino fish recommended in the draft advisory should refrain from eating other fish during the period of time identified in the advisory.

Fish Advisories