by Jeff Meyers
Republished with permission, Lake Champlain Committee “Shorelines” Spring 1999
At dusk the fisherman begins casting the river, his line baited with a minnow. He keeps the bait on or very near the bottom, hoping to drag it across a sandbar next to deep water where walleye tend to school. Soon after dark, the first fish strikes, and as luck would have it, it is a big one, a fighter. In the light of his flashlight, the fisherman sees the fish in his net is probably over 20 inches ling. But despite the fact that walleye are renowned for their savory flesh, the fisherman will not eat this fish—the flesh of Lake Champlain walleye is polluted with mercury.
Eating too many large walleye is dangerous, New York and, Vermont have issued health warning against the consumption of large walleye and other predatory species like lake trout
Ironically, there used to be a connection between the flashlight the fisherman uses to look at his fish and mercury that keeps him from eating it.. Many alkaide batteries used to contain mercury.
Fish absorb mercury in the form of methylmercury directly from the water and from eating smaller fish and aquatic organisms. Metlylmercury binds to fish tissues, including muscle, and does not break down. Unlike other toxins such as PCBs that reside in fatty fish tissue and can be filleted out, mercury is impossible to remove with a filet knife. Moving easily through the food chain from prey to predator, it accumulates in aquatic organisms and their predators, and becomes progressively more concentrated (“biomagnifies”) towards the top of the food chain, in fish, birds, and mammals. Greater amounts of methylmercury are found in older fish which absorb more and more methylmercury with each fish they eat. The most desirable sportfish—the largest, oldest predators—are the most highly polluted.
Mercury in Lake Champlain
Since the 1970s, scientists have measured mercury in Lake Champlain’s fish. Vermont and New York State fish monitoring from 1988-1994 found that mercury levels in large walleye taken from the Missisquoi, Great Chazy, Lamoille, and Poultney Rivers were at or above 1.0 parts per million (ppm). This discovery led both states to issue health advisories for consumption of walleye from the Lake. There are now also health advisories from lake trout, chain pickerel, smallmouth bass and other fish.
Mercury is a highly toxic metal which affects the central nervous system. At very low levels, mercury can cause severe health effects including irreversible damage to the central nervous system, muscle tremors, behavior and personality changes, digestive disorders, skin rashes, kidney damage, blindness, and deftness. The period between exposure and the onset of symptoms may be months or years. Levels as low as 200 parts per billion in blood can cause the first affects of mercury poisoning. Because it targets the nervous system, mercury is particularly dangerous for fetuses (whose nervous systems are still developing), and mercury exposure will cause birth deformities. Thus there are specific health advisories for children and women of child bearing age. As a precautionary measure, the New York Department of Health recommends that individuals falling into these categories eat no fish from Lake Champlain. A fish with mercury concentrations of 1.0 ppm is considered unsafe for human consumption by the United States Food and Drug Administration.
The most infamous episode of mercury poisoning occurred from 1953 to 1982 when there were 1,800 verified cases of human mercury poisoning in Minymata Bay , in Kyushu, Japan. The victims had consumed fish with very high concentrations of methylmercury from a nearby chemical plant. As concentrations of methylmercury increased to toxic levels in their bodies, people grew sick and many died. Autopsies show concentration form 2 to 70 ppm.
Fortunately, there is no direct source of mercury to Lake Champlain comparable to the Minymata Bay chemical plant. Only trace amounts enter the Lake naturally. With only minor natural inputs and no direct industrial source, scientists wonder where the mercury is coming form. How does is get into the Lake?
Sources of Mercury Pollution
The major source of mercury pollution in the Basin, it turns out, is the sky, In the nation, various combustion and manufacturing sources emit an estimates 137.2 tons of mercury per year. Coal fired electric utilities are the worst offenders. Municipal, commercial and medical waste incinerators follow a close second. Other combustion sources, which include a variety of industrial practices, contribute the rest. Forty three percent of the mercury contamination in Basin air, water and soil comes from sources within New York State and the New England region.
Although most atmospheric mercury pollution comes from distant fossil fuel power plants, we are all guilty of mercury pollution. The flashlights that anglers used to use for night fishing were powered with batteries that contain mercury. Many common consumer products still contain mercury including batteries, electrical components, switches, plastics, dyes, thermometers, fluorescent light tubes, latex and anti fouling paints, fungicides, and household disinfectants A few years ago even LA Gear sneakers (the ones that flashed) contained mercury. Mercuric oxide button cell batteries contribute the most mercury to the waste stream; approximately 40% of all mercury used in the US is in household batteries. Waste stream mercury has a very low bio-availability—it is “locked up” and unavailable to biological processes—while it remains bound to these materials. When burned in incinerators (which operate at temperatures as high as 2000 degrees), however, mercury tends to vaporize and enter the air in the form of a gas or as microscopic particles. From there is will eventually be deposited by rain or snow onto the land and waterbodies.
Significant quantities of mercury have already built up in forests and in water bodies in sediment and fish. So it is essential that we act now to stop additional mercury pollution. Mercury pollution prevention means altering behaviors and processes so that the contaminant is never generated, to avoid having to treat or control it after generation and disposal. If we could reduce the use of mercury-containing substances, modifying our use of raw materials, and changing manufacturing processes perhaps fish advisories and the negative recreational and economic implications for the basin could become a thing of the past. Perhaps we can stop mercury from raining from the sky onto our cherished waters.
Solving the Problem
EPA recently released its long-awaited “Mercury Study Report to Congress”. Mandated by the 1990 Clean Air Act, the study documents mercury pollution sources and troubling trends in mercury pollution in the US.
In 1998, a regional study assessed the impacts of mercury emissions in the Northeast States and Eastern Canadian Provinces. Because this study did not fully speak to conditions in Vermont, the Vermont General Assembly created the Governor’s Advisory Committee on Mercury Pollution to report on the extent of mercury contamination to Vermont’s soil, water and air; examine health risks from mercury contamination in Vermont: and suggest methods to minimize risk of further contamination or increased health risk.
Also in 1998, passage of Vermont Senate Bill S. 181—which LCC lobbied for—required manufacturer labeling and the take-back by manufacturers of mercury-added consumer products, as well as addressing larger public health issues of mercury pollution. Beginning this year manufacturers of mercury-added products sold at retail in the state must inform the consumer of the existence of the mercury-added products collection system, and of the fact that the disposal of mercury-added consumer products is prohibited. Manufacturers will also establish a toll-free telephone number to provide information about mercury disposal and recycling.
In New York, a secondary mercury refining plant is Albany has shut its doors and is now serving as a transfer station to more efficient mercury recycling plants. Many incinerators are shutting down, although two facilities still in operation (Onandaga and Niagara Falls) have been retrofitted with the latest mercury controls. The State has adopted federal rules for combustion and waste incineration and is looking to tighten emissions at most plants. Along with the other Great Lakes states, New York is undertaking a solid mercury inventory before taking comprehensive actions to assure they the receive the biggest bang for their buck in mercury reduction. Volunteer pollution prevention methods are gaining ground. The state, for instance, is encouraging voluntary removal of mercury switches in junked automobiles before crushing, an effort pioneered in Buffalo area but now expanding into the rest of the state.
At the federal level, Senator Patrick Leahy of Vermont introduced the omnibus Mercury Emissions Reduction Act March 1998. The bill seeks to direct the EPA to promulgate mercury emissions standards for the largest emitting source categories, particularly fossil fuel utilities and solid waste incinerators. The bill would also require reports by EPA to Congress on progress in implementing mercury emission reductions. Leahy will also be looking for opportunities to enact pieces of the Omnibus bill in connections with electric utility deregulation legislation.
Increasing awareness about ways to remove mercury from the waste steam will go a long way toward reversing the trend of mercury pollution in Lake Champlain. Two additional Vermont programs will also contribute to solving the mercury problem: mercury collection at schools and at dairy farms. School chemistry labs and dairy farm manometers (used in milking parlors) contain many ponds of mercury that can be removed and replace by less toxic alternatives.
It’s No Only People Who Want to Eat Fish
Mercury poisoning is a threat to more than just people. It is important to thinks of the many other fish eaters that are at risk as well. The Lake’s loons, osprey, merganser, mink and otter—to name just a few species—can not read fish advisories. These animals suffer from biomagnification of mercury in fish. According to Dr. Mary Watzin of the University of Vermont, more research is needed to determine the health threat of mercury pollution to the fish themselves, as well as the meat-eating birds, and furbearers. A number of studies document the neurological and behavioral disorders that result in fish, birds, and furbearing carnivores from high doses of mercury, but, unfortunately, these studies involve experimental injection of mercury at higher doses than animals receive through diet—more on the order of Minymata Bay than Lake Champlain. Few studies have addressed mercury at levels animals are exposed to through the food web of the Lake.
Watzin has studied the effects of mercury on juvenile walleye at levels consistent with their exposure in the Lake. She found that there are significant reproductive impacts from mercury exposure to walleye, particularly males. Mercury exposure slowed growth of the fish and resulted in smaller testes. These smaller testes contained a greater number of atrophied (non-functioning) cells. Mercury pollution may not only make walleye dangerous to eat, it may be causing a steady decrease in walleye populations.
Although more research is needed, it is reasonable to suspect that similar negative impacts are occurring with the Lake’s other predatory fish species, as well as loons, cormorants, mergansers, mink, and otter. Our more prudent use of this highly toxic material will help alleviate their suffering as ell as our own.
Tips on reducing use and ensuring proper disposal of mercury-containing products:
For questions regarding disposal of mercury as hazardous waste, contact the following
In New York