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Where it Comes From and What It’s Doing to the Food Chain
Early in 2003, the Food and Drug Administration (FDA) announced dramatically lower safety limits for mercury in fish and has plans to extend its list of fish to avoid, pending tests that could reveal mercury in the fish above the new “safe” limits. Mercury is a well-established potent neurotoxin, and researchers have described its harmful effects, particularly on the developing fetus, for decades. By following the latest FDA guidelines, consumers–especially pregnant women and parents of young children–can make better choices when including fish in their diets; but the complex story behind mercury contamination of our marine and freshwater food supply reveals many unsavory sources of pollution as well as a conflict of interest in our so-called watchdog government agencies.
The FDA lowered its previous “safe” standard from 1 part per million (ppm) of mercury in fish to the threshold of 0.2 ppm recommended three years ago by the National Academy of Science (NAS) based on their 2000 study on mercury.
It has been clear since the infamous 1950s case of women in Minimata, Japan who gave birth to children with severe birth defects because of mercury-tainted fish in their diet, that exposure to high levels of mercury can be harmful. Subsequent studies have revealed that even low-level mercury exposure threatens normal development of the fetus. Problems with vision, hearing, language and motor skills are typical of mercury-related neurological damage. The National Academy of Sciences (NAS) estimates that over 60,000 US children are born each year at risk for life-long problems because of dangerous blood levels of mercury in their mothers.1 Young children, whose brains are still developing, are also at risk of being harmed as are adults, who may suffer from cognitive, motor or immunological problems that are difficult to diagnose until mercury exposure is considered. Researchers are only now beginning to explore the life-long deleterious effects of mercury exposure. Some recent studies indicate that men with elevated mercury levels may suffer more heart attacks. Animal studies suggest that low-level mercury exposure produces autoimmune diseases and other immune system anomalies.2
Something Fishy Going On
But why did the FDA wait until only this year to issue stricter safety limits for fish? For years, the National Academy of Sciences, public health activist groups and individual scientists have requested complete and specific information about the dangers of mercury in fish.
In 2001, the FDA issued a warning for pregnant women and young children to avoid eating tilefish, swordfish, shark and king mackerel because they contained dangerous levels of methyl mercury. Further, the FDA cautioned the same group of consumers not to eat more than 14 ounces of any type of fish per week. However, the FDA did almost nothing to make sure that Americans learned of this important information, either by implementing their promised public education program, or by printing warning labels for packages of fish or posting warnings on restaurant menus. What’s worse, the FDA mentioned nothing at all about the dangers of consuming tuna, ignoring the urging of consumer groups and its own scientists.3 Although the amount of mercury in canned tuna is considered “moderate” when compared to other fish, many people, including children, eat canned tuna regularly, even up to a can per day, so the potential for mercury to reach dangerous levels is great.
The Environmental Working Group (EWG), an organization well known for alerting consumers to the dangers of pesticides, obtained over one thousand pages of transcripts on seafood and mercury from FDA-sponsored public “focus groups” in Denver, Boston, and Calverton, Maryland held in October and November, 2000. The transcripts reveal several instances in which FDA scientists directly contradict agency guidelines and admit to participants that the then-current “safe” levels of mercury in fish, including tuna, are not protective of the unborn. These guidelines advise against anyone eating more than one and a half 6-ounce cans of tuna per week.4
Further, from other publicly available FDA documents the EWG discovered that while drafting the final language for their fish advisory, the highest officials from the FDA met privately three times that fall with executives from Chicken of the Sea, Starkist, Bumble Bee, the US Tuna Foundation and the National Food Processors Association. These “big fish” from the seafood industry obviously had more influence than the FDA’s own scientists and Advisory Committee, or the NSA, for in the final version of the FDA’s advisory, published on January 12, 2001, methyl mercury warnings had been watered down, and there were no references at all to tuna.
Obviously, we will wait in vain for the seafood industry to warn consumers of potential dangers in its own products. But the FDA had completely abdicated its role as public defender by allowing the tuna industry to take advantage of a study on the benefits of fish and omega-3 fatty acid consumption to promote tuna as a healthy choice for pregnant women: According to a US Tuna Foundation press release, “. . . this new study adds to the long list of startling health benefits scientists believe omega-3 fatty acids provide to pregnant women and small children. The most convenient, economical source of omega-3s for moms and kids is, quite simply, canned tuna!”5
It is clear that mercury in fish poses health problems, and that citizens are left, once again, to shoulder the responsibility of educating themselves in order to protect their families’ health in the face of duplicitous government agencies. But the closer one looks at the tragedy of our poisoned fish supply the more interwoven are the many threads from seemingly unrelated sources that lead to an ecosystem out of balance. There is no way to ignore the fact that we all share one earth, one biosphere in which our transgressions against nature, either from ignorance or greed or malice, eventually affect us all.
Mercury depositions into earth’s oceans and waterways continue apace and there are several sources of contamination that may not at first seem obvious. Numerous studies have fingered emissions from coal-burning power plants as the main source of mercury pollution in many parts of the world. A 2002 study from the University of Santa Cruz, California illuminates the mechanisms of one such pollution pathway. This study found that mercury from coal emissions in China ends up in rainwater on the California coast.6 Atmospheric mercury travels around the globe as a gas and must be oxidized into charged ions that will attach themselves to water molecules before they are washed out as rain. Ozone, abundant in industrial and urban smog, plays a key role in this oxidative process. When the gaseous mercury blows into San Francisco Bay from Asia, the local smog is there waiting to “enrich” it and set in motion the process of introducing more mercury into the food chain via rain onto surface waters. In other words, it is not enough to curtail mercury emissions alone; local pollution levels directly influence the rate of deposition.
Interestingly, the same report noted that much of California’s mercury contamination is the result of mining operations during the Gold Rush when miners used large amounts of liquid mercury to extract gold ore. These operations left enormous areas of contaminated sediments along the watershed that ultimately drains into the San Francisco Bay. Researchers in the study also found that long-abandoned mine sites in coastal regions still continue to leach mercury into rivers and streams that end up eventually in the San Francisco Bay. State officials have issued advisories warning against consumption of fish that inhabit more than a dozen bodies of water in California, including San Francisco Bay.
Gold mining has also played a role in the mercury contamination of the Amazon River, which ultimately empties into the Atlantic Ocean. The 1970s gold rush in the Amazon basin attracted thousands of itinerant gold miners who used mercury to extract gold ore. An estimated 100 to 150 tons of mercury per year have entered the environment via dumping or evaporation; many studies cite “astronomical” levels of mercury in soils and rivers near mining areas.7
Researchers were initially puzzled when mercury levels equal to those in mining districts were found very far downstream (400 km) from active mining sites. Scientists from the University of Quebec, who have been studying the Amazon basin since 1992, contend that the source of most of the contamination is a natural result of millennia of volcanic action. Compared to the soils of Quebec, which are the result of glaciation about 10,000 years ago, soils in the Amazon are much more ancient, perhaps more than one million years old. This is a very long time for mercury to accumulate to substantial levels. Yet why was the mercury suddenly leaching from the soil?
The researchers measured riverbank sediments for mercury levels in small increasing increments and discovered that the most recent sediments contained 1.5 to 3 times the amount of mercury compared to those of 40 years earlier. The timing of the mercury increases fits well with the huge colonization of the area initiated during the 1960s by Brazil’s National Institute of Colonization and Agrarian Reform. Through this program, tens of thousands of families relocated from the poorer regions of northeastern Brazil to the Amazon basin. Most of these families turned to farming, and cleared more than 2.5 million hectares of Amazon forest using “slash and burn” methods. While most people are aware of the perils of deforestation in terms of global warming and depletion of protective ozone, only now are scientists beginning to understand that the consequent erosion of soils contributes to worldwide mercury contamination. “When you have forest cover, this mercury is extremely stable in the soils,” explains one of the researchers. “There is hardly any release to the aquatic ecosystem. The mercury is bound to clay, organic matter, humic acids, and so on.”8 Without the forest cover, exposed soil is washed into waterways as regularly as it rains. Once in contact with bacteria in the rivers, inorganic mercury is converted to methyl mercury and thereby introduced into the food chain.
The Canadian researchers are helping local populations respond to the mercury contamination by advising the consumption of only herbivorous fish. For the long term, however, different means of land use are required–not an easy prospect in a region lacking abundant capital.
Mercury continues to appear in places and via means that scientists have not predicted. Two studies in the March 15, 2002 issue of Environmental Science and Technology describe the phenomenon of “mercury sunrise,” an event first described in 1998 in the Arctic north. During a span of only five months during the polar spring each year, the northern-most coast of Alaska receives more than twice the amount of mercury that falls during an entire year on the northeastern coast of the US. This phenomenon also occurs on the southern polar region as well, and researchers estimate that from 50 to 300 tons of mercury are dumped on both poles annually.9
The “mercury sunrise” occurs in the presence of ultraviolet light, open water and active sea ice, all of which have been increasing at both poles in recent decades. When the sun finally rises after the long polar winter, it triggers a chemical reaction that causes vaporized atmospheric mercury to rain down onto the snow packs where it can be acted on by bacteria and then enter the food chain. According to one of the research teams, these new findings shed light on the rising levels of mercury in Arctic sea birds, seals and beluga whales.
One of the same researchers who studied the mercury sunrise phenomenon in remote polar locations also led a team that found high levels of methyl mercury in gas venting from municipal landfills much closer to home. In the July 7, 2001 issue of Science News, Steve E. Lindberg of the Oak Ridge National Laboratory in Tennessee demonstrated that interred mercury-containing wastes, including medical wastes, fluorescent bulbs, batteries and old latex paint, are acted on by the same bacteria that methylate inorganic mercury in bodies of water, and that the methyl mercury then enters the air via the venting pipes in the landfills. His findings helped to explain the presence of methyl mercury in air and rain, which had confounded scientists prior to the landfill venting discovery.10 Lindberg plans to initiate inventories of landfill emissions, especially of older ones containing the most abundant stores of mercury-containing wastes. He also calls for technological means of trapping the methyl mercury before it enters the atmosphere. Preventing the problem by excluding mercury-containing wastes from landfills would be a vigorous first step, but one that is unlikely to be implemented given the convoluted politics and tangled bureaucracies of waste management.
The most stupeyfying and inexcusable source of mercury contamination is the US military’s toxic war on the earth. We seem to have entered an era of “permanent war” with US bombardment commonplace throughout the planet and the military’s never-ending need to consume and pollute growing like a cancer. According to Bob Feldman, reporting in the March/April, 2003 issue of Dollars and Sense, “the Department of Defense is the world’s largest polluter, producing more hazardous waste per year than the five largest US chemical companies combined.” The two largest offenders are Washington’s Fairchild Air Base, which produces the most hazardous waste among military bases–13 million pounds in 1997 alone–and Oklahoma’s Tinker Air Force Base, which emits the greatest amount of toxics–over 600,000 pounds in the same year.11
In June, 2001, the Military Toxics Project and the Environmental Health Coalition issued their report, “Defend Our Health: A People’s Report to Congress,” with details on the Pentagon’s war against the earth.12 The list of contaminants emitted from military bases from coast to coast, from Alaska to Hawaii to Puerto Rico, includes pesticides, solvents, petroleum, lead, mercury and uranium. A 1999 report by the Pentagon’s own Inspector General documents pollution at US bases in Canada, Germany, Great Britain, Greenland, Iceland, Italy, Panama, the Philippines, South Korea, Spain and Turkey.13 And since the Pentagon runs its bases as “federal reservations,” they operate above the law both at home and in the host countries, where the full extent of contamination cannot be ascertained by local authorities until after a base is closed.
Activists around the globe are calling attention to target-range bombardment, abandoned munitions and radioactive waste which are part of the ongoing poisonous legacy of the US military. The tiny island of Vieques, just a short ferry ride from the main island of Puerto Rico, has become a symbol of independence as it struggles to exist in the midst of the US Navy’s War Zone. Citizens of Vieques should be enjoying life in a beautiful Caribbean paradise; instead 45 percent of them have excessive blood levels of mercury.14 According to epidemiologist Dr. Carmen Ortiz Roque, the only known source of mercury contamination in Vieques is US Naval exercises. Predictably, cancer rates are high among Viequenses, along with other debilitating diseases and birth defects.
In 1985, the Navy began reporting to the EPA on heavy metals released into the waters of the impact areas near Vieques. Measurements showed at least 20 substances exceeding boundaries set by the Clean Water Act, including lead, cadmium, arsenic, boron, cyanide and hexavalent chromium. Further, the Navy admitted in 1999 to illegally firing 263 rounds of depleted uranium on Vieques; the same radioactive armaments used in the US bombings of Yugoslavia, Afghanistan and Iraq.
Humans are not the only species under siege at Vieques. Coral reefs and at least 13 endangered species face extinction if bombing and toxic contamination continue. The Navy, however, goes on contemptuously firing a whole host of live weapons into the ocean, both within the Vieques firing range and on the high seas in a range extending 200,000 square miles from Vieques, almost to the coast of Venezuela. The Pentagon is now promoting a bill in Congress that would exempt military exercises from environmental regulations such as the Clean Air Act, the Clean Water Act and laws that protect endangered species.
Local Viequenses have mounted many valiant protests against Navy despoliation of their home and local ecology, joined by many international supporters. These voices of protest have either been ignored or violently put down by the FBI and US Federal Marshals.15
The Bush administration’s request for 399.1 billion dollars for the Pentagon in 2004 includes 16.9 billion dollars for the Department of Energy’s nuclear weapons activities. The aim is to gradually restore nuclear warhead production to Cold War levels.16 Aside from the horrors that could be unleashed by the use of this bristling array of nuclear armaments is the deadly pollution that results from their manufacture. According to Nuclear France: Materials and Sites, the US uses lithium hydride for boosted fission warheads and lithium deuteride for the fusion stage in thermonuclear warheads. “The greatest threat to the general population and to the environment is indirect. The production of lithium traditionally requires a great deal of mercury, and the manufacturing plants have generated considerable pollution by this heavy metal.”17
Returning our focus to the dinner plate, we will find some guidance regarding safer types of fish to eat. Several sources recommend a rather short list, including summer flounder, wild Pacific salmon, croaker, sardines, haddock and tilapia. Of course when choosing fish, mercury is certainly not the only contaminant to consider, so this list may be bigger or smaller depending on what kinds of fish are available in your vicinity. Fresh water species like catfish and trout may contain lower levels of mercury, but are often heavily contaminated with DDT.
There are also certain foods that can help the body release mercury stored in tissues. Several years ago a researcher studying a possible connection between chronic bacterial infections and heavy metals in the body, found that some patients released mercury into their urine after eating Vietnamese soup containing cilantro (Coriandrum sativum).19 This effect has been replicated in other studies, although scientists have not yet determined exactly which constituents in cilantro have mercury-chelating effects. As a preventive, then, cilantro can be eaten, fresh and raw, as a regular part of the diet to orally chelate not only mercury, but lead and aluminum as well.
According to the Marine Technology Society, brown seaweeds, such as kelp, contain fucoidan and algin, which have been shown to remove lead, mercury, cadmium, barium, tin and other heavy metals from tissues.20 Seaweeds also help remove radioactive isotopes from the body. Using seaweeds both as a condiment and at least several times a week as a vegetable (so that you consume a half-cup serving) is necessary for chelating action to take place.
So if it weren’t for universal pollution and over-fishing, we could enjoy our fish dinner in peace! While ignorance is certainly not bliss, as readers of this journal well know, knowledge ought to empower its seeker. And although the struggle for a clean, healthy food supply often seems a contest between David and Goliath, the outcome of that Biblical confrontation, after all, was the diminutive David. In this continuing struggle, there are, will be and must be many heroes of David’s moral stature.
Fish to Avoid
According to both EPA and FDA sources, the following fish are best avoided altogether by pregnant women, and consumption should be restricted for the rest of us.
|Tuna (fresh or frozen)||0.32|
The fish in this list represent large, carnivorous varieties whose natural lifestyles make them prime candidates for concentrating mercury in their tissues. Tinned tuna has lower comparative mercury concentrations since smaller tuna species are typically caught for the canning industry, yet it represents by far the most frequently consumed fish in American diets. Not only is it tasty, but it is far less expensive than the other varieties, and is available practically anywhere year round. Source: FDA and EPA
Mercury is not the only threat to fish in our oceans. During the past fifty years, industrial fishing methods have reduced the populations of large fish such as tuna, marlin, swordfish, sharks, cod and halibut by an astonishing 90 percent, and according to researchers some species are very close to extinction.16
Researchers from the Biology Department of Dalhousie University in Nova Scotia found that it takes industrial fisheries only 10 to 15 years to reduce target fish populations by 80 percent. Compounding this intense worldwide over-fishing is the fact that fish species that require years to mature before they can reproduce now rarely reach full size and are caught long before they have a chance to replenish stocks.
While data has been accumulating to suggest that fish stocks have been declining recently, it was still thought that larger fish reservoirs existed far out in the open oceans. The Dalhousie University team was able to document that the fish declines spread consistently from four continental shelf and nine oceanic systems. They urge immediate action to create marine reserves that are restricted to fisheries and to limit the numbers of fish that are caught.
- Mercury in the Environment, on-line factsheet; www.usgs.gov/themes/factsheet/146-00
- N. Shute, Heavy Metal Fish, U.S. News & World Report, March 17, 2003
- J.H.Lee and D. Zuckerman, Can We Trust Charlie Tuna? FDA Negligence on Methyl Mercury, Red Flags Weekly, August 26, 2002; www.redflagsweekly.com/features/2002_august26.2.html
- Executive Summary, Focus Pocus, the FDA withholds information from pregnant women on mercury-contaminated fish…Environmental Working Group on-line report; www.ewg.org/reports/FocusPocus/es.html
- Mercury in California Rainwater Linked to Industrial Emissions in Asia; Media Alerts Archive, December 19, 2002; www.earthobservatory.nasa.gov/Newsroom/MediaAlerts/2002/2002121911028.html
- R.C.Willis, Mercury Rising: Deforestation and gold mining in the Amazon basin cause the release of toxic metal, Today’s Chemist at Work, March 2001, vol. 10, No. 3, pp 30-36
- T. Steele, “Mercury sunrise” effect found in Antarctica, EurekaAlert!; www.eurekalert.org/pub_releases/2002-03/acs-sp031902.php
- J.Raloff, Landfills make mercury more toxic, Science News, vol.160, no.1, July 7, 2001
- B. Feldman, The U.S. military’s war on the Earth, Dollars and Sense, March 13, 2003
- Military Toxics Project, www.miltoxproj.org/magnacarta/magnacarta.htm.
- Chemical Weapons Working Group. www.cwg.org/pr_01.13.99y2k2.html.
- A. Thomas Conteris, Vieques Si, Bombing, No!, Fellowship of Reconciliation Task Force on Latin America and the Caribbean, 2002, www.forusa.org/Programs/puertorico/ViequesSi_Conteris.html
- Analysis of new FY 2004 military budget, Council for a Livable World; www.clw.org/milspend/dodbud04.htm
- M.Byrd Davis, The six nuclear materials: Lithium; Nuclear France: Materials and Sites, 8/25/01.
- R.A. Myers and B. Worm, Rapid worldwide depletion of predatory fish communities, Nature, 423: 280-283 (2003)
- D. Williams, Poor Man’s Chelation Therapy, on-line version, www.home.earthlink.net/~jedcline/cilantro.html
- S. Weed, Healing Wise, Ash Tree Publishing, 1989, p.223.
This article appeared in Wise Traditions in Food, Farming and the Healing Arts, the quarterly magazine of the Weston A. Price Foundation, Summer 2003.