Warning Over Fish Mercury Levels (Heart Attacks)

Eating certain types of fish can increase the risks of having a heart attack, a study suggests. A team of international researchers has found a direct link between mercury and heart disease.

High levels of mercury are found in shark, swordfish, king mackerel and marlin. It is also found at lower levels in fresh or frozen tuna.

These new findings do not affect our current advice for people to try to eat fish twice a week

Belinda Linden, British Heart Foundation The researchers have suggested that people should consider eliminating fish with high mercury levels from their diet.

The UK's Food Standards Agency recently advised pregnant women and children against eating this type of fish.

There are fears that mercury can damage the nervous system of unborn infants and can increase the risks of poisoning in young children.

These latest findings are based on a study of more than 1,400 men from eight European countries including Britain, and Israel.

Researchers examined mercury levels in 724 of these men, who have had a heart attack. They did this by analysing their toenail clippings.

Levels of mercury in toenails are regarded as a reliable way of determining whether someone has had long-term exposure to the chemical.

They also examined the toenail clippings of the other men, who had no history of heart disease.

Their analysis found that mercury levels in men who had had a heart attack were 15% higher than those with no history of heart problems.

Their study also suggested that any of the benefits associated with eating fish may be lost if they have high mercury levels.

The Omega 3 fatty acids in fish are believed to have a protective effect on the heart.

Writing in the New England Journal of Medicine, the researchers suggested that the general public should be advised against eating fish with high levels of mercury.

"Exposure to methylmercury is currently a concern in specific high-risk groups, such as pregnant women and women of childbearing age who may become pregnant but this warning should perhaps be extended to the general adult population."

"A weekly intake of two to four servings of fish from a variety of species with special emphasis on fatty fish with low mercury content, such as salmon and small oceanic fish, is consistent with current advice for reducing cardiovascular risk."

"Whilst the benefits of eating fish are well known, this research confirms that this can be counteracted by mercury which the fish accumulate," said Belinda Linden, its head of medical information.

"These new findings do not affect our current advice for people to try to eat fish twice a week, including one portion of oily fish such as sardines and mackerel.

"This quantity should offer the benefits of omega-3 oils in fish while avoiding any potential harmful effects."

EPA Home Mercury

Frequently Asked Questions

Where does mercury come from? Are mercury levels increasing?

Mercury is a naturally occurring element that is present throughout the environment and in plants and animals. Human activity can release some of that mercury, increasing the amount available to accumulate in humans and other animals. Human activities have increased the amount of mercury that is currently cycling in the atmosphere, in soils, and in lakes, streams and the oceans. Mercury in these locations increases risks to people and wildlife. Although the U.S. and many other industrialized countries have substantially reduced mercury uses and releases in recent decades, these reductions are not yet reflected in the air, soils, water or fish.

What is methylmercury?

There are three forms of mercury -- methyl, elemental, and inorganic. Releases of mercury to the environment are usually in the form of elemental or inorganic forms. Methylmercury is an organic form of mercury. Biological processes change the chemical form to methylmercury, which is the more toxic form found in fish. Methylmercury bioaccumulates through the food chain and, once in the body, can affect the fetal and adult nervous systems. What are the biggest sources of mercury air emissions? According to EPA's 1997 Mercury Study Report to Congress, coal-fired electric utilities are the largest source of human-caused mercury air emissions in the U.S. Utilities are followed by:
1. Municipal waste combustors (19 percent);
2. Medical waste incinerators (10 percent);
3. Hazardous waste combustors (4+ percent).

How does mercury move through the environment?

In the atmosphere, mercury is transported by wind either as a vapor or as particles. Mercury reaches waters either through direct deposition or as run-off from soil after rain. In the water, biological processes can transform mercury into methylmercury – a highly toxic form, which can accumulate in fish.

How does mercury from power plants wind up in fish?

When mercury is deposited into the water, microorganisms help convert it to methylmercury, a highly toxic form of mercury. Small organisms and plants take up the mercury as they feed. As animals higher up the food chain eat those plants and organisms, they, too, take in methylmercury. The process continues, with levels of mercury increasing, up the food chain. This process is known as bioaccumulation. Fish higher in the food chain, such as sharks and swordfish, have much higher mercury concentrations than fish lower on the food chain.

How much does the U.S. contribute to worldwide mercury emissions?

Although the amount of mercury the U.S. contributes globally is small (about 3 percent), it still contributes more than it receives. Approximately two-thirds of U.S. mercury emissions are transported outside our borders. However, approximately 60 percent of the mercury deposition that occurs in the U.S. comes from domestic, human-made sources of pollution. The highest deposition rates from U.S. sources occur in the southern Great Lakes, the Ohio Valley, the Northeast, and scattered areas in the Southeast.

How does mercury affect health?

At high doses, mercury exposure can cause tremors, inability to walk, convulsions, and even death. At levels more commonly seen in the United States, the mercury exposure effects documented include more subtle – yet still serious – damage to the senses and brain.
The developing fetus is the most sensitive to the effects of mercury, and so women of child-bearing age are the population of greatest concern. Children of women exposed to relatively high levels of methylmercury during pregnancy have exhibited a variety of abnormalities, including delayed onset of walking and talking, and reduced neurological test scores. Children exposed to far lower methylmercury exposures in the womb have exhibited delays and deficits in learning ability.

Do some fish contain more mercury than others?

Yes. Freshwater fish caught by recreational or subsistence fishermen (people who fish for their food) from contaminated waters have been shown to have particularly high levels of methylmercury. Certain species of commercially available saltwater fish, such as shark and swordfish, kingfish and tilefish also can contain high levels of mercury.

How much will EPA reduce mercury emissions from power plants?

On DATE, EPA announced it will regulate emissions from power plants. That's the first step toward developing regulations. Next, EPA will begin the work to propose regulations (December 15, 2003). The Agency will issue final regulations by Dec. 15, 2004.

What else is EPA doing to reduce mercury emissions?

EPA has taken a number of recent actions to reduce mercury pollution, include issuing stringent regulations for industries that significantly contribute to mercury pollution. These actions, once fully implemented, will reduce nationwide mercury emissions caused by human activities by about 50 percent over 1990 levels. They include:
Municipal waste combustors (MWCs) emitted about 20 percent of total national mercury emissions into the air in 1990. EPA issued final regulations for MWCs on October 31, 1995. When fully implemented in the year 2000, these regulations will reduce mercury emissions from these facilities by about 90 percent, from 1990 emission levels.
Medical waste incinerators (MWIs) emitted about 24 percent of total national mercury emissions into the air in 1990. EPA issued emission standards for MWIs on August 15, 1997. When fully implemented in 2002, EPA's final rule will reduce mercury emissions from MWIs by about 94 percent from 1990 emission levels.
Hazardous waste combustors (HWCs) emitted about 2.5 percent of total national mercury emissions in 1990. In February 1999, EPA issued emission standards for these facilities, which include incinerators. When fully implemented, these standards will reduce mercury emissions from HWCs by more than 50 percent from 1990 emission levels.
In addition, U.S. industrial demand for mercury dropped 75 percent from 1988 to 1997. The drop can be attributed to a number of actions, including:
federal bans on mercury additives in paint and pesticides; industry efforts to reduce mercury in batteries;
increasing state regulation of mercury emissions and mercury in products;
state-mandated recycling programs; and
voluntary actions by industry.
EPA supports the efforts of state and local governments to achieve mercury discharge reductions through outreach and technical assistance for mercury pretreatment programs at sewage treatment plants. EPA also assists states and tribes in developing innovative regulatory approaches, such as the market-based emissions reduction program for the State of Minnesota.

("Most of the tuna sold in the US is caught in the Pacific which doesn't have a source of mercury.")

Debate focuses on tuna safety (Canned)

07/26/02
By BEN RAINES
Mobile Register
Staff Reporter

BELTSVILLE, Md. -- An independent panel convened by the U.S. Food and Drug Administration decided Thursday that the FDA needs to tell women and children to eat less canned tuna, which accounts for more than 25 percent of all seafood eaten in this country.

The panel, charged with reviewing the advice FDA gives to kids and women of childbearing age regarding mercury in seafood, recommended other significant changes in FDA policy. But the question of how much canned tuna can safely be eaten was the most contentious issue during the three-day conference.

Panelists recommended that FDA craft a warning more in line with states such as Wisconsin, Maine and seven others, which advise consumers to limit tuna consumption to just one can per week.

Scientists know that babies born to women with high levels of mercury in their bodies are at increased risk for birth defects.

Some research has shown that much lower levels of mercury -- less than those found during Register-sponsored hair testing of Gulf Coast residents -- also lead to lower IQ's in children and delays in their key developmental milestones, such as walking and talking.

After testimony from FDA officials, the commercial fishing industry, the U.S. Environmental Protection Agency and consumer advocacy groups, the Food Advisory Committee panel found that FDA's existing advice -- that women and children can safely consume two cans of tuna per week -- might expose children and fetuses to dangerous levels of mercury.

"The burning question," said Dr. Michael Shannon with Children's Hospital in Boston, "is whether it is safe for kids to be eating tuna fish sandwiches for lunch every day."

He and the other panelists agreed that neither FDA nor the fishing industry had provided evidence that settled that question. The committee also recommended that FDA begin investigating the effects of mercury on children, an area of research that panelists felt had been overlooked.

The panelists also challenged FDA to publish the methodology it used to arrive at what FDA scientists consider a safe level for mercury in the human body. The FDA's safe level is four times higher than the level the EPA, the National Academy of Sciences and the European Union believe to be safe.

Asked if the agency would comply, Joseph Levitt, the director of the FDA's Center for Food Safety and Applied Nutrition and the senior official in charge of the agency's mercury policy, said FDA would "be taking that advice to heart."

In all, the panel made eight recommendations to the FDA, though during a press conference after the meeting FDA officials presented only seven. Only after questioning from the Register did Levitt acknowledge the panel's final recommendation.

That recommendation, that the FDA add more fish to the so-called "Do Not Consume" list if they are found to be as high in mercury as the fish already on that list, could ultimately have the most powerful impact on the fishing industry.

FDA now advises women of childbearing age and children to avoid all swordfish, tilefish, shark and king mackerel, because those fish have average mercury levels over 1 part per million.

Asked if FDA would enforce that recommendation, Levitt said, "We're going to have to go back and see what the ramifications are."

It appears the ramifications might include listing some of the most popular and expensive commercially caught fish on the "Do Not Consume" list. Register-sponsored fish testing last year indicates that grouper, redfish, cobia, amberjack and tripletail may also qualify for the "Do Not Consume" list.

In addition, the very databases used by FDA to create the existing "Do Not Consume" list show that a number of important commercial fish, such as black grouper and some species of tuna, clearly qualify for the list, based on the agency's data.

"If you look at the distribution of mercury levels for a number of species in the Gulf of Mexico, clearly there are a number of species that will be added to the 'Do Not Consume' list, such as bluefish" said EPA's Kate Mahaffey, author of the 1998 Mercury Report to Congress and the agency's senior official dealing with mercury in fish and people.

Asked if the panel's findings were significant, Levitt was unequivocal.

"Oh yes," he said. "As I said, the committee felt we had started in the right direction but that we had a ways to go."

Mahaffey, who helped create the EPA's safe level for mercury in the human body, was somewhat guarded in assessing how the conference went.

"EPA has given FDA many of these same recommendations over a number of years. Consequently it remains to be seen whether FDA will implement the advice of their advisory committee," Mahaffey said. "Of course EPA looks forward to working with them if they do this."

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