The state's largest doctors' group has recommended that fresh and canned fish carry labels informing consumers about the health dangers from excessive amounts of mercury.

The resolution by the influential California Medical Association encourages physicians to educate their patients on the dangers of mercury in food, particularly fish, and to advise pregnant women and children to limit consumption of fish with significant concentrations.

Mercury is toxic to the nervous system and particularly to a developing fetus. The most common exposure comes in the diet from consuming large oceangoing fish such as swordfish, shark and tuna that accumulate the poison in their bodies.

Such species as salmon, tilapia, sardines, sole, Pacific red snapper and small shrimp are known to be low in mercury.

"We're pushing away from high fat and high cholesterol. We consider fish to be healthy," said Rob Margolin, chairman of the CMA's San Francisco delegation.

"But fish that is high in mercury, we're coming to learn, can be quite dangerous."

One of the contentious issues at the CMA's annual meeting last week in San Francisco was the question of labeling fresh, packaged and canned fish, Margolin said.

"Some people were a little nervous whether fishermen would be upset. But our push was to study the issue more fully, better measure mercury in fish and educate the public. We need the label so people can know what they're eating."

The association had invited San Francisco physician Dr. Jane Hightower to write the resolution. In November, Hightower published a study showing a correlation between eating swordfish, tuna and other large fish and the presence of significant levels of mercury.

Hightower was pleased that the resolution was passed.

"People are now blindly buying fish, and unknowingly consuming the highest mercury content fish sold in the market. We need to identify the fish that have low mercury levels. If we have appropriate labeling, we could do that," Hightower said.

The state group intends to refer the resolution to the American Medical Association's annual meeting in June.

On Tuesday, scientists in the Centers for Disease Control and Prevention published a paper on mercury in fish in the Journal of the American Medical Association, based on a CDC study released in February on human exposure to environmental chemicals.

In examining the U.S. data, they found that mercury levels among women who ate three or more servings of fish in the prior 30 days were almost four times higher than among women who ate no fish. Levels were almost twice as high in children who ate fish compared to children who didn't eat fish, the study found.

"We don't want to overly worry women. Overall, the levels of exposure are fairly low. But we do reiterate in our conclusions that women who are pregnant or intend to become pregnant should pay attention to federal and state advisories on consumption of fish," said lead author Susan E. Schober, an epidemiologist in the CDC National Center for Health Statistics.

In February, state Attorney General Bill Lockyer sued grocery stores, charging that their failure to label certain types of fish for mercury is a violation under the state's anti-toxins law, Proposition 65. Safeway, Whole Foods, Trader Joe's and Albertson's have agreed to post warnings at the fish counter, but the suit has not yet been settled.

On Monday, 10 groups, including Physicians for Social Responsibility, sent a letter to Lockyer asking him to add canned tuna to the Prop. 65 warnings.

"Canned tuna is one of the most consumed fish in the U.S., and in some cases the only fish pregnant women and kids eat. Ten states now warn pregnant women . . . to limit canned tuna consumption," the letter said.

For more information visit the following Web sites: www.epa.gov/mercury/fish.htm and www.cfsan.fda.gov/.