Don't Eat That Fish

High mercury levels in fish have prompted a new nationwide advisory: The species you bring home could make you sick.

Field & Stream Online Editors

It is the most basic of human rights: to fish for food, to take from the bounty of our waters a healthy meal for ourselves and our families. The practice is as old as mankind, from a caveman bent over a river with a sharpened stick to a modern angler powering a cast into the waves with a surf rod. But that right is under a grave threat.

Most fishermen today are familiar with some form of fish consumption advisories, because almost every state has waters that are contaminated by industrial chemicals or other toxic substances such as dioxin or polychlorinated biphenyls (PCBs). Dealing with toxins is one of the sadder facts of being a sportsman in the modern world. And while federal and state agencies have made progress in reducing many kinds of water pollution, one poisonous substance is very much on the increase, and it may turn out to be more dangerous than all the others combined.

That substance is mercury-the most widespread and pervasive toxin now found in the fish that we like to pursue and eat. To date, 45 states have fish consumption advisories for mercury. In December 2003, the Food and Drug Administration (which monitors fish that are sold commercially) collaborated with the Environmental Protection Agency (which monitors fish caught by sportsmen for private consumption) to issue a comprehensive warning on eating mercury-contaminated fish.

A Toxin Through History
People have known the dangers of mercury since the Roman empire, when slaves who worked in the "quicksilver" mines invariably died after less than three years. More recently, the expression mad as a hatter arose because mercury was used to preserve beaver pelts in the 19th century, and the craftsmen who made the hats would become bald and suffer from severe muscular tremors and dementia, including uncontrollable fits of laughter.

But the most terrible instance was identified in 1956, in Minimata Bay, Japan, where a chemical company dumping mercury caused a rash of ghastly birth defects and afflicted thousands of people with what came to be known as Minimata disease. Stray cats, which had long survived by scavenging from the many fish-packing businesses in this port city, were the first to show symptoms of poisoning. Investigators puzzled over the mysterious "dancing cat disease," so called due to the bizarre muscular spasms that wracked the cats before they died. It was the first time in history that the phenomenon of bioaccumulation came to the attention of scientists.

There is nothing complex about the process. Mercury is a naturally occurring toxin, found in soils, rocks, wood, and fuels like coal and oil. Simple soil erosion deposits mercury in rivers and lakes, but concentrations remain low, unless, as has been discovered in the recently deforested regions of the Amazon, erosion reaches extraordinary levels. Burning wood also releases some mercury that has been taken up from the soil by trees.

But of all the sources of mercury, it is our burning of coal to generate electric power that is the single greatest contributor to the problem. Mercury that naturally occurs in the coal is released during burning and enters the air; it is then precipitated into the oceans, lakes, and rivers by rain. According to the EPA, coal-fired power plants in the United States emit about 48 tons of mercury into the air every year-and more than half of this mercury falls within 10 kilometers of the plant itself. When it reaches the water, microorganisms consume it and convert it into a substance called methylmercury. Into the Food Chain
A study at the University of Tennessee recently rated methylmercury among the most dangerous poisons on Earth (just behind plutonium). It has no known beneficial use, and it accumulates in the muscle tissue of fish, animals, and humans. When minnows eat plankton or algae that is contaminated with methylmercury, it is deposited in their flesh; rger fish prey upon the minnows, and the toxin travels straight up the food chain to our most revered and noble gamefish-the big predators like bass, pike, walleyes, brown trout; and to all the finest food and sport fish of the seas-tuna, swordfish, marlin, halibut. According to the EPA, fish at the top of the aquatic food chain bioaccumulate methylmercury to a level approximately 1 million to 10 million times greater than dissolved concentrations found in surrounding waters.

Of course, when you climb one more rung up that food chain, you find us, the fishermen of the world and the millions of people who buy their fish from their local supermarket. Just like the predatory fish that we catch and eat, we store mercury in our tissues. Just like the ancient Romans, we know that high exposure to mercury is fatal. But according to the EPA and other government agencies, it is the gradual buildup of mercury over a lifetime of low-level exposure that poses the most widespread risk.

Women and Children First
At the greatest risk are young children and women who hope to become mothers. A recent report from the Centers for Disease Control found that one in 12 women of childbearing age has elevated mercury levels. Birth defects can occur even with amounts too low to cause illness in the mother.

Mercury is a neurotoxin, which means that its effects are primarily concentrated in the brain and central nervous system. The least horrific of the related birth defects are the ones that are the most difficult to measure-impaired brain development, leading to diminished memory, vision, coordination, and learning ability, especially difficulties with attention span and language skills. The same problems are associated with high levels of mercury in young children, whose nervous systems continue to develop until age 14.

Federal and state advisories focus on how much and what species of fish can be hazardous to women and children, but there are increasing signs that adult men, and women beyond childbearing age, are also at risk. "One of the problems with the advisories is that they can make [BRACKET "mercury"] seem like a women's issue only," says Dr. Jane Hightower, an internist at the California Pacific Medical Center in San Francisco, who is conducting extensive research into how elevated levels of methylmercury impact human health. "And that is not correct. I am seeing people that are ill from this all the time."

Hightower believes that we are just beginning to understand how the toxin, at different levels, affects individuals. "We have the data from Minimata Bay and other places regarding the effects of mercury poisoning," she says. "At a certain level of contamination you will see muscular tremors, hair loss, personality disorders, birth defects, inability to concentrate, and various illnesses. We know that for a fact. But the evidence has been trickling in for years that much lower mercury levels are linked to heart attacks, impaired cardiovascular function, muscle and joint problems. I have patients with a host of similar symptoms, who have not been able to get a conclusive diagnosis for what was wrong with them, and the common link we found was elevated mercury levels."

Hightower also says that accumulated mercury undermines the overall function of the body. "Whatever your weakness," she says, "[BRACKET "mercury"] will make it worse."

A Threat to Rich and Poor
Hightower's studies have so far focused on upper-income patients from around the San Francisco Bay area-people who eat a lot of big, predatory fish like tuna and swordfish. "But I'd like to work with the sport and subsistence fishermen, too," she says. "This is clearly a growing problem for both the poor who fish for their food, and the wealthy who buy the more expensive kinds of fish."

Hightower worries that many of the advisories available to fishermen are so complicated that they might be ignored. "The California advisory that comes with your fishing license is very good, and if you try to follow those rules, you can catch and eat fish that are healthy for you. But let's be clear about this: If you are eating fish all the time-I had one guy who ate 30 meals of fish a month-you are going to be in trouble. You have got to pay attention. Don't freak out about this; just pay attention. I tell people that they've got to rotate their poisons. Don't eat the same thing day after day."

Coincidentally, the new FDA-EPA fish consumption advisory was issued in the same month that the EPA released new proposed federal regulations to control mercury emissions from coal-fired power plants. Such regulations have never existed.

Mercury Rising?
In 1997, the EPA under the Clinton administration presented a detailed study that revealed the hazards of mercury contamination, pinpointed coal-fired power plants as the leading source of emissions, and promised action. But nothing was done. The EPA had begun work on a plan to address mercury pollution in December 2000; in a 2001 presentation, the agency said that 90 percent of mercury emissions from coal-fired power plants could be cut, using what is known as the Maximum Achievable Control Technology (MACT), by 2008.

Many environmental and fishing organizations expected that, with mercury pollution having attained such a high profile, the Bush administration would follow the MACT plan, but that was not to be. Instead, the EPA has unveiled a very different set of regulations that promises to reduce overall mercury levels by 70 percent by 2018. The new policy places them under a "cap and trade" system, where polluters trade "credits" for complying with the law. According to an EPA press release, this approach will be "the most cost effective way to achieve reductions." Indeed, such a strategy has shown success in reducing the emissions that cause acid rain.

But Felice Stadler, the National Wildlife Federation's national policy coordinator for their Clean the Rain Campaign, has worked on the mercury issue for the past four years and believes that the cap and trade system, as it applies to mercury, is a disaster. "Mercury is far too toxic to be placed under this system," she says. "Under the Bush plan, you will have seven times more mercury released into the waters than if we just simply followed the Clean Air Act as it is written today. There will be no overall reduction in mercury. Every other major source of pollution has been subject to the requirements of the Clean Air Act, until now. The Bush administration has simply decided that the coal-fired power industry will be exempt."

Several states have already decided that the federal plan is too lax. New Jersey announced in December that it will follow the MACT plan. Massachuseto complicated that they might be ignored. "The California advisory that comes with your fishing license is very good, and if you try to follow those rules, you can catch and eat fish that are healthy for you. But let's be clear about this: If you are eating fish all the time-I had one guy who ate 30 meals of fish a month-you are going to be in trouble. You have got to pay attention. Don't freak out about this; just pay attention. I tell people that they've got to rotate their poisons. Don't eat the same thing day after day."

Coincidentally, the new FDA-EPA fish consumption advisory was issued in the same month that the EPA released new proposed federal regulations to control mercury emissions from coal-fired power plants. Such regulations have never existed.

Mercury Rising?
In 1997, the EPA under the Clinton administration presented a detailed study that revealed the hazards of mercury contamination, pinpointed coal-fired power plants as the leading source of emissions, and promised action. But nothing was done. The EPA had begun work on a plan to address mercury pollution in December 2000; in a 2001 presentation, the agency said that 90 percent of mercury emissions from coal-fired power plants could be cut, using what is known as the Maximum Achievable Control Technology (MACT), by 2008.

Many environmental and fishing organizations expected that, with mercury pollution having attained such a high profile, the Bush administration would follow the MACT plan, but that was not to be. Instead, the EPA has unveiled a very different set of regulations that promises to reduce overall mercury levels by 70 percent by 2018. The new policy places them under a "cap and trade" system, where polluters trade "credits" for complying with the law. According to an EPA press release, this approach will be "the most cost effective way to achieve reductions." Indeed, such a strategy has shown success in reducing the emissions that cause acid rain.

But Felice Stadler, the National Wildlife Federation's national policy coordinator for their Clean the Rain Campaign, has worked on the mercury issue for the past four years and believes that the cap and trade system, as it applies to mercury, is a disaster. "Mercury is far too toxic to be placed under this system," she says. "Under the Bush plan, you will have seven times more mercury released into the waters than if we just simply followed the Clean Air Act as it is written today. There will be no overall reduction in mercury. Every other major source of pollution has been subject to the requirements of the Clean Air Act, until now. The Bush administration has simply decided that the coal-fired power industry will be exempt."

Several states have already decided that the federal plan is too lax. New Jersey announced in December that it will follow the MACT plan. Massachuset