Last modified: November 29. 2002 12:00AM
Studies differ on risks of mercury

By Linda A. Johnson
Associated Press

Two studies have yielded contradictory findings about the possible heart dangers of eating mercury-laden fish.

Plenty of research shows that mercury accumulated from fish can harm the developing brain of a fetus or child. Far less is known about how the toxic, widespread pollutant affects the heart.

Two studies in Thursday’s New England Journal of Medicine on the long-term effects of mercury exposure on the hearts of middle-aged and elderly men had opposite findings.

One found no clear link between mercury levels in the body and the risk of developing heart disease; the other found men who had suffered a heart attack had higher mercury levels than similar men who had not.

That left the researchers, Food and Drug Administration officials and other experts agreeing on just two things: More research is needed, and people should not stop eating fish, because minerals and fatty acids in fish protect the heart. Also, many fish, such as salmon and shrimp, contain little or no mercury.

"The bottom line is, yes, you should eat fish, and yes, you should know which fish have mercury" levels considered unsafe, said Dr. Daniel Shindler, a cardiologist at Robert Wood Johnson Medical School in New Brunswick, N.J., who was not involved in either study.

The American Heart Association, citing new research showing the omega-3 fatty acids in fish reduce the risk of heart disease, last week reiterated its guidelines that people eat at least two servings of fish per week, preferably fatty fish.

Researchers at the Johns Hopkins Bloomberg School of Public Health reviewed data and tissue samples from an earlier, nine-country European cardiac study. They compared 684 middle-aged men who had had one heart attack with 724 similar men who had not had a heart attack.

Those with the highest mercury levels were nearly 2.2 times more likely than those with the lowest levels to have had a heart attack, said Dr. Eliseo Guallar, assistant professor of epidemiology at Hopkins.

Researchers at Harvard School of Public Health studied 470 men who had had heart surgery or a heart attack, comparing each with a similar man without heart disease. Dr. Walter Willett, a professor of epidemiology and nutrition, said mercury levels in the men’s toenails corresponded well with the levels of fish they reported eating, but his team found no association between mercury exposure and heart disease.

"We can’t exclude the possibility that there’s some moderate risk," Dr. Willett said.

 

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