Mercury Rising

Al Hanners is a retired oil geologist who worked worldwide for a major U.S. oil company for nearly four decades, and who was a Middle East geologist for that company in the early 1970s.

Mercury ingested in any form is toxic to humans, and methylmercury in fish is a worldwide health problem. However, as Georgia-Pacific admittedly dumped tons of mercury into Bellingham Bay, our local focus has been on mercury in the bay and on mercury in fish in Lake Whatcom. Bellingham and Whatcom County have jointly hired the United States Geological Survey (USGS) to study mercury in Lake Whatcom and in other local places. The fieldwork was done in 2002 and the report on the study is long overdue. It might be released in September or October of 2003.

In the mean time, it is rumored that two sources of mercury were found in sediments. One is pre-1960, and is called archival; the other is post-1960 after Georgia-Pacific started to use and dump mercury. As will be elucidated below, some of the mercury found by the USGS almost certainly came from “worldwide” airborne pollution. Hence, we can expect the USGS report to cast light on the answers to these difficult questions: How accurate is the 1960 date? How much of the post-1960 mercury is from Georgia-Pacific? How much is from “worldwide” airborne pollution?

This article provides a broad perspective that fills some gaps. It is a brief synthesis of illness caused by mercury, where mercury comes from, how it is spread about the world, how it gets into fish and what we can do.

Health problems from ingesting too much mercury were not well known until the 1950s when an epidemic hit fishermen and their families living in Minamata Bay in Japan. People whose diet was mainly seafood suffered brain damage and even died. An investigation traced the health problem to methylmercury from a local chemical plant that discharged mercury into the bay.

While focus on mercury locally has been on mercury in freshwater sport fish in Whatcom County, and statewide on mercury in fish in lakes and streams, the fact is that far more Americans are endangered by eating too much of two species of saltwater fish because people eat more of them than they do other fish. Those species are wild tuna and farmed salmon. Tuna are of concern because of the mercury they contain; farmed salmon can be dangerous to health because of the large amounts of PCBs.

This article is about mercury and certainly PCBs are a digression; but everything is connected somehow. For me, the information on PCBs in farmed salmon is a by-product of research on mercury in fish. The high level of PCBs in farmed salmon in the United States results from what they are fed, bottomfish. Bottomfish are depleted to a crisis level because fish farms have proliferated.

There is abundant evidence that mercury is a worldwide problem; hence, here are only a few points from the “Mercury Policy Project (MPP)” Web site. Vermont is leading the nation on safety in the consumption of mercury, and MPP is based there.

• Over 65 mercury product bills have been introduced in 24 states in the year 2003.

• On June 26, 2003, the World Health Organization (WHO) recommended a new mercury exposure standard that is nearly twice as stringent as the existing WHO standard.

• The European Union released the position paper “Ambient Air Pollution by Mercury” on Oct. 17, 2002.

While tuna does not have as much mercury as some other top predatory fish, canned tuna is the chief mercury health threat to fetuses, nursing babies, and to young children whose brains are not yet fully developed, because mothers and young children eat a great deal of tuna. Canned tuna is said to be consumed in 90 percent of American households and accounts for 20 percent of U.S. seafood consumption. Children eat twice as much tuna as any other fish, and canned tuna is the most frequently consumed fish among women of childbearing years.

There are no agreed-upon world standards, and even the U.S. Food and Drug Administration (FDA) and the Environmental Protection Agency (EPA) do not agree on guidelines. However, the National Academy of Sciences in 2000 found the EPA’s reference dose justifiable for protecting most Americans. That reference dose is 0.1 microgram of methylmercury per kilogram of human body weight per day. It’s doubtful that most Americans would make that calculation. Hence, the following table based on that reference dose might have more utility because more people would use it. Once mercury enters our tissues, it stays there for the rest of our lives. The guidelines are merely estimates of how much methylmercury we can consume before we have obvious ill health, or we die of other causes. There may be no really safe guidelines.

Pounds body weight/Ounces chunk white Albacore tuna consumed per week

• Pregnant women and women nursing babies probably should eat less.

• This table can be used as a guideline for other marine top predatory fish. People eating other kinds of tuna could eat a little more. People eating shark, swordfish or other top predatory fish, probably should eat a little less of them.

• Mercury was found in fish in all 21 waterbodies in Washington that have been sampled by the Department of Ecology, has been reported in Oregon, and is well known in waterbodies scattered throughout the United States. Hence, this table could be used as a rough guideline for larger freshwater fish in the United States.

The MPP web site states, “Recently obtained information from the FDA reveals a seafood mercury monitoring program severely lacking in thoroughness, depth and degree. The report says that although the FDA is charged with protecting the public from mercury-contaminated seafood, by it’s own admission, FDA no longer conducts a monitoring program for tuna (canned, steaks and sushi), shark or swordfish.” The tuna industry seems to have a powerful long arm.

Is that the reason that I have never, never seen articles in popular press urging people to eat more fish while at the same time saying, “Wait a moment, consider what the mercury could do to the health of you and your family?”

Mercury is a very unusual metal and the only common metal that is liquid at normal room temperatures. It quickly becomes vaporized when heated. In nature, it rarely is uncombined with other elements. The common commercial mercury ore is cinnabar, a red mercury sulphide that mainly is obtained from Spain and Italy. Metallic mercury is obtained by heating cinnabar and condensing the vapor.

Ores of iron and aluminum do not contain mercury, but important ores mined for some other metals do contain mercury. When those ores are smelted, mercury becomes volatile and is passed into the atmosphere. Airborne mercury from the burning of coal is generally regarded as a very important source of mercury in fish. It will be commented on more fully below.

Mercury has been used to make medicine to treat syphilis. More importantly, there are two medical uses that are controversial. Mercury has been used to make amalgams since 500 B.C., and currently mercury amalgams are the substance of choice for filling dental cavities. Fortunately, children seldom have dental cavities while their brains are still developing. In comparison, consuming mercury-contaminated fish would appear to be a more serious health risk. However, pregnant women could pass mercury from dental fillings to their fetuses. The most serious problem resulting from dental amalgams is mercury amalgams drilled out of cavities and discarded and flushed into the sewer. While there have been some efforts to make that practice illegal, so far they have been unsuccessful.

The most controversial use of all is the use of mercury in vaccines for infants. Hundreds of lawsuits have been filed by parents claiming that mercury induced autism in their children. However, reliable evidence is hard to come by because the U.S. Justice Department under Attorney General John Ashcroft has requested the courts to seal the documents. It seems that action was taken to protect the vaccine manufacturer by keeping information from the general public.

Mercury is used in thermometers, barometers, electrical switches and in mercury vapor lamps to light highways. The commercial use of mercury in equipment is normally not particularly dangerous to the public. It is improper disposal of mercury in worn out equipment, in sewer systems and landfills that is the chief problem. As a result, some commercial uses of mercury are being phased out.

Worst of all commercial uses of mercury is as a catalyst in the production of chlorine. Chlorine is used to kill bacteria in drinking water, in making bleaches for household uses, and in the production of white toilet tissue and other white paper. It was the production of chlorine by Georgia-Pacific in Bellingham for decades starting in the 1960s, and dumping many tons of discarded mercury in the shipping channel waterway in Bellingham Bay that led the public to consider mercury in fish in Lake Whatcom to be a local problem. However, at least a portion of our current mercury problem probably is part of a larger worldwide problem.

The Department of Ecology Publication No. 03-03-026, “Mercury in Edible Fish Tissue and Sediments from Selected Lakes and Rivers of Washington,” was published in June 2003. Twenty lakes and streams scattered throughout the state were selected and, to no surprise, all fish tissue contained mercury, some more than others, but none with very large concentrations. The widespread occurrence of mercury indicates two things. First, from a health point of view, mercury is likely to occur in the many waterbodies that were not tested. While there is no guarantee without testing, eating modest quantities of fish from any of them is not likely to be a serious threat. Second, from the point of view of the origin of the mercury found, there is widespread occurrence where there is no credible evidence of a local geologically primary source of mercury. Therefore, a widespread airborne source is indicated.

Older, larger fish in the same waterbody contained more mercury than smaller fish of the same species, but size differs from waterbody to waterbody. Therefore regression studies relating fish size to mercury content were done so mercury content of a single fish size could be used as a standard for comparing the lakes and streams selected. Only 15 out of 20 waterbodies had adequate data and significant correlations between fish length and mercury concentration. Of those 15 waterbodies, fish from Moses, Upper Long and Banks lakes were found to have adjusted mean mercury concentrations that were significantly lower than the other waterbodies. The Department of Ecology did not venture a reason for the lower mercury concentration in those three waterbodies.

However, it is interesting to note that all three are artificial lakes formed by dams. The water in Banks and Moses lakes is pumped from the Columbia River at the Grand Coulee Dam to provide water for irrigation. The water is not from drainage basins around the lakes that could be expected to have anaerobic wetlands where airborne mercury could be converted to methylmercury. Upper Long Lake was created by a dam on the Spokane River. Hence, if a larger percentage of the Columbia and Spokane River drainages are in slope than the flatter area where most of the 15 waterbodies occur, one might expect less methylmercury in fish in Banks, Moses and Upper Long lakes. To me, these results corroborate the theory that the principal source of mercury found in the June 2003 study is airborne.

The June 2003 Department of Ecology report does not include the fish tissue sampling reported in “Lake Whatcom Watershed Cooperative Drinking Water Protection Project. Results of 1998 Water, Sediment and Fish Tissue Sampling,” September 1998. Presumably the reason is that the 1998 study analyzed composite samples of fish tissue and no attempt was made to normalize the mercury content to fish of a single size. The high concentration of mercury in smallmouth bass in Lake Whatcom Basins 2 and 3 has been taken by some observers to indicate mercury entering Lake Whatcom in water diverted from the Nooksack River. However, the September 1988 report states that, “Mercury concentration in muscle fillet was generally found in moderate concentrations with the exception of one smallmouth bass sample from Lake Whatcom (0.5 mg/kg). That sample was a composite of eight very large specimens collected from Basins 2 and 3, with an average weight of 2 pounds. Therefore, mercury in that sample probably reflects the size of the specimens and the feeding habits of smallmouth bass.”

There appears to be a consensus among most scientists and environmentalists that the burning of coal is the principal source of mercury in fish. Most of that coal is burned in coal-fired electrical power plants. While efforts to reduce mercury contamination by making some other industrial uses of mercury illegal are commendable, realistically, no significant reduction of ingestion of mercury in humans can be made without reducing emissions of mercury from coal-fired power plants. On the positive side, environmentalists claim mercury emissions from coal-fired power plants can be reduced significantly. On the down side, the principal sticking point has been that coal-fired power plants were grandfathered in the Clean Air Amendment of 1990.

However, that covered only the plant and equipment in place when the act was passed. Power companies did not modernize plants, because if they did, they would have to also abide by the Clean Air Amendment. Now all that has changed for the worse. Claims are being made that to prevent reoccurrence of the recent widespread blackout in the eastern United States and Canada, the plants must be modernized at costs of billions of dollars. The Aug. 8, 2003, Bellingham Herald ran an article by the New York Times that said, “In one of its far reaching environmental actions, the Bush Administration signed a rule that will allow thousands of refineries, pulp and paper mills, chemical plants and other industrial facilities to make extensive upgrades that would increase their pollutants without having to install new antipollution devices.”

Whether or not there is a reduction of mercury emissions from coal-fired power plants in eastern United States is of great importance to people living there, but given that we have the great Pacific Ocean on our west, live in a region of prevailing westerly winds, and have no significant coal-fired power plants along the coast, if any, we have our own set of airborne mercury problems. Much of our current airborne mercury probably comes from China, not coal-fired plants in eastern United States. Here is what was said in the “Study of Mercury in Whatcom Fish,” by Al Hanners, in the June 2002 issue of Whatcom Watch:

“Atmospheric scientists are said to be able to detect when Chinese begin to till their fields in the spring. An article on global pollution published by The Bellingham Herald on May 26, 2002, said, ‘For the United States, China is a major source.’ Coal usually contains mercury, and burning it releases mercury to the atmosphere. China has little petroleum and natural gas and burns much coal. Hence, our ‘global’ source of airborne mercury might be from China.”

I was on a 10-day tour of eastern China over a decade ago at the time of the Tienemen Square uprising. The day before we left China we actually got caught in the traffic jam at the Square as hundreds of people, most of them workers, not students, marched into the Square. Those 10 days were a memorable time in China. The Chinese were very friendly with Americans, spoke out freely, and even sought us to have their pictures taken with us. One of our Chinese guides was the most informative. He had been a champion swimmer who learned to swim in the Grand Canal. He also fished there during his youth. The Chinese Government is making a determined effort to industrialize China and now the Grand Canal is little better than an open sewer.

He said the government knows what it is doing to the environment, but its policy is to sacrifice the environment to achieve their goal. Moreover, we have to consider U.S. policy. Expect U.S. companies dependent on imports from China to resist putting pressure on China.

Mercury is highly volatile. The consensus among scientists and activists appears to be that when coal is burned, mercury becomes airborne as fine particules. For example, that conclusion was corroborated by researchers in Minnesota who published in the Science News issue of March 9, 2002. Mercury in the Cobb River peaked in May and June when metallic mercury from leaves washed into the river. Methylmercury peaked in November when metallic mercury in dead leaves had been converted to methylmercury.

Airborne metallic mercury particulates do not indiscriminately drop everywhere. Smoggy and foggy conditions tend to cause airborne particles to drop out. It is said that fish in the Everglades in Florida have the highest mercury content of any fish in the United States, and that has been attributed to smoggy conditions in the Everglades. For mercury to be ingested by fish, mercury must first be converted to methylmercury by anaerobic bacteria.

Requirements for the process include the presence of mercury and the oxidation of metallic mercury, and the presence of organic matter and an oxygen-deficient environment. Those conditions are found in wetlands, some lakes and streams, and some wet landfills. In waterbodies methylmercury is taken up by plankton, which is eaten by larger organisms. It is concentrated by passing up the food chain to successively larger organisms with predatory fish having the most mercury. It also is concentrated with increasing age of the fish.

How mercury gets into marine fish is not as clear as how it gets into freshwater fish. Metallic mercury is converted to methylmercury on land and virtually all rivers and creeks flow into the sea. But also, particulate metallic mercury falls out of the atmosphere far out at sea where top predators such as swordfish and tuna live. The saltwater there contains oxygen. Therefore, does all the methylmercury in those top predators originate close to land, or is some metallic mercury far out to sea converted to methylmercury by a process not reported on land?

Whereas the primary source of mercury is in ores associated with siliceous igneous rocks of geologically shallow origin, mercury is sedimentary in coal just like coal itself. Coal is organic matter that originated in anaerobic swamps, most of them near marine shorelines. Seashores are notorious for foggy conditions. That fog is believed to have caused airborne mercury from volcanoes to drop preferentially into those swamps. The principal constituent of marketable coal is carbon that plants had extracted from the atmosphere. As the coastal areas subsided and were filled with marine sediments, the overlying load of sediments on the organic swamp material increased. As the organic material was compacted, more and more hydrogen left, principally as methane, and coal was formed.

Mercury forms compounds with a number of elements, and for our purposes here there are three important forms: metallic mercury, mono-methymercury, and di-methylmercury. Mono-methylmercury is water-soluable; di-methylmercury is not water-soluble and is the form that comes off landfills and wetlands as a gas. However, that gas is unstable and reverts to airborne metallic mercury or some other mercury compound. Much of that mercury is recycled again and again unless it is semi-permanently or permanently stored in animal bodies or in coal.

When a coastal swamp is near the edge of a tectonic plate and is plunged very deep into the earth by tectonic processes, the mercury becomes one element of many in magma and is released once more into the atmosphere by volcanoes, and the whole process begins again. §