Chapter 2: Mercury
Mercury is a naturally occurring element that has no nutritional value and is a potent neurotoxin. This means that it interferes with the way nerve cells function. Mercury’s dangers have been established for centuries—noted by both the ancient Romans and Incas.
Despite this, mercury is used in, and is a byproduct of, many industrial processes and consumer products. In Oregon, the major sources of industrial mercury are mercury-added products (such as thermostats, thermometers and fluorescent lamps), point sources (such as power plants that burn coal, commercial and industrial boilers, steel mills, and cement kilns), and abandoned mercury and gold mines. Additional sources of mercury in Oregon include laboratories, dental offices, health care facilities, global emissions, and erosion of native soils. The total amount of mercury released from human sources to air, water, and land in Oregon is estimated at approximately 4,500 pounds annually.30
Oregon's two largest source of mercury emissions are the coal-fired power plant at Boardman, emitting an estimated 165 lbs a year, and the Ash Grove cement kiln in the Eastern Oregon town of Durkee, emitting an estimated 2,500 lbs of mercury a year.31 In 2004, the Ash Grove Cement plant was the third largest source of airborne mercury in the nation.32
Once released mercury circulates in the atmosphere and deposits on land and water. Mercury entering water can be transformed into methylmercury, a highly toxic form of mercury that bioaccumulates in the muscle tissue of fish and biomagnifies in animals that eat fish. When a substance biomagnifies its concentration increases as it moves through the food chain. This study tested for the presence of methylmercury. The most common way people are exposed to mercury is by eating fish containing methylmercury.33 Just one gram of mercury (the amount in just two typical thermometers) can make the fish in a 20-acre lake unsafe to eat.
The EPA and the FDA have jointly determined a reference dose for mercury of 0.1 ºg/kg body weight per day, which corresponds to a blood mercury level of 5.8 ppb for women of childbearing age, pregnant and nursing women, and children under the age of fifteen. The EPA reference dose is defined as the amount of mercury a person, including sensitive subpopulations, can be exposed to on a daily basis over a lifetime without appreciable risk of effects. Currently men over age 16 and women over age 49 have no mercury exposure level guidelines. These guidelines are needed in order to be able to determine safe levels of mercury exposure for these populations. While mercury is naturally excreted, it can take months to leave the body after exposure. In addition, most people are regularly exposed to mercury in the environment and food.
Mercury in Oregonians
Oregonians are most directly exposed to mercury by eating contaminated fish. Oregon has 12 fish advisories due to mercury contamination covering 435 miles of waterway, including the entire main stem of the Willamette River.34
Methylmercury was detected in the blood of all ten Oregonians we tested. Methylmercury is a particularly toxic form of mercury as it specifically targets the central nervous system. Figure 3 shows that a wide range of mercury was detected in the participants, from 0.37 to 3.5 ppb, with a median of 1.83 ppb. Mercury levels for all but one Oregonian tested were higher than the national median of 0.70 ppb.35
Figure 3: Methylmercury levels measured in blood. The horizontal line depicts the national median value of 0.70 ppb.*
At 3.5 ppb, Alan Bates had the highest methylmercury level in our group. High blood methylmercury levels are often thought to correlate with fish-rich diets, but Alan did not report consuming the highest levels of fish among the participants, although he does eat fish occasionally (once a week). While it is difficult to know what accounts for Alan’s high methylmercury level, without a more in-depth evaluation of his exposures and habits, it is likely that the fish he does consume is contaminated with high levels of mercury. His results demonstrate that while fish consumption can be a significant source of mercury contamination for Oregonians, the exposure also depends on where the fish came from and the type of fish you consume.
Health Effects of Mercury
Many adverse health effects are associated with the accumulation of mercury in the body. They vary depending on the amount of mercury one is exposed to, time of exposure, chemical form of the mercury, and age of the subject.
Methylmercury, the most common form of mercury to which people are exposed, is a very potent neurotoxin that interferes with brain development. Once in the brain it interferes with nerve cell differentiation and cell division by binding DNA and RNA. Methylmercury can cause nerve cell death and scarring in selected areas of the brain.36 In the case of methylmercury poisoning, numbness is the first sign of damage to the nervous system.37 Other symptoms that may follow a higher dose of methylmercury poisoning are stumbling or clumsy gait and generalized weakness. Higher doses of methylmercury poisoning may lead to speech difficulties, loss of vision and hearing, tremor, and finally, coma and death.38
Young children and fetuses are more sensitive to methylmercury than adults.39 Mercury in the mother’s body passes to the fetus and may accumulate there. It can also pass to a nursing infant through breast milk. Children exposed to methylmercury in utero show irreversible damage to their central nervous systems: numbness and tingling around mouth, fingers and toes; a clumsy stumbling gait; difficulties swallowing and speaking; general weakness and fatigue; vision and hearing loss; spasticity and tremor; and seizures. Methylmercury interferes with cell division and migration of cells in the developing brain.40 Prenatal mercury exposure has also recently been implicated in preterm birth.41 According to the CDC, 8% of U.S. women of childbearing age have enough mercury in their blood to pose a threat of neurological damage to the fetus.42
Chronic exposure to methylmercury in adults may also produce cardiovascular problems,43 though studies have not yet determined a reference dose for the level of exposure that might trigger these effects. There is some evidence that methylmercury may function as a hormone disruptor and may play a role in diseases such as breast cancer.44
Policy Changes Needed
Regulation of mercury is particularly difficult because it readily moves between media; from release into the air and deposition in land and water, to bioaccumulation in animals and people. In addition, mercury is produced as an unintentional byproduct of mining and other industrial processes, so we are continually producing more of it. One emerging problem involves how to capture and store excess mercury. Also, absent regulations, excess mercury in the United States can be sold on the international market. Subsequently, mercury sold abroad can eventually be released by production facilities back into the air and recontaminate Oregon's environment and people. At the federal level, the Mercury Market Minimization Act is being proposed to help reduce the amount of mercury circulating in the global marketplace.
Many states have acted to limit mercury exposure, use, and production. A number of states have implemented broad mercury reduction efforts, such as Connecticut (phase out all anthropogenic discharge of mercury), Massachusetts (requires manufacturers to collect mercury containing products), and California (controlling mercury throughout its lifecycle). Other states including Oregon, Maine, New Hampshire, Illinois, Indiana and Washington have focused on eliminating mercury-added products. Maryland is focusing on getting mercury out of schools, and Michigan has focused on getting mercury out of hospitals. Several local jurisdictions around the country also have adopted restrictions on sales of products containing mercury.
Eliminate the use and sale of mercury-containing products. Oregon has begun to address the problem of mercury releases through the Mercury Reduction Act of 2001 which has phased out use and sale of certain mercury-containing products such as fever thermometers, auto switches and novelty products. Although mercury-containing thermostats can still be sold under this legislation, they cannot be installed by contractors.
Reduce mercury emissions from power plants. Oregon has adopted a Utility Mercury Rule that limits mercury emissions for new plants and mandates installation of mercury control technology for Oregon’s only existing coal-fired power plant. The rule requires that the power plant achieve a 90% reduction in mercury emissions by 2012. If the 90% reduction is not technologically achievable, the coal-fired power plant must install continuous mercury monitoring equipment by 2008 and develop a mercury reduction plan. In the long-term, coal burning should be replaced with conservation and cleaner energy production.
Reduce mercury emissions from manufacturing facilities. Oregon Department of Environmental Quality (DEQ), in partnership with the Ash Grove Cement plant and local community and environmental organizations, are working on a plan to reduce mercury emission through the installation of control equipment. The mercury reduction effort is a voluntary effort specific only to Ash Grove as it is the only cement manufacturing plant in Oregon. To avoid excessive mercury pollution, the state should require that all facility retrofits and every new facility constructed in Oregon use the best available technology.
Health care facilities, including hospitals and dental offices, should phase out mercury containing products in favor of safer alternatives. For several years, the Oregon Dental Association, local governments, and Oregon DEQ have been promoting voluntary environmental best management practices to reduce mercury contamination from dental amalgam in dental offices.
In 2007, the Oregon Legislature passed a requirement regulating dentist disposal practices of amalgam fillings that contain between 40 and 50% mercury. If no protective measures are taken, mercury from amalgams ends up in air after being incinerated with medical waste, or in water if disposed of down the drain. This legislation requires installation of amalgam separators in all dentist offices, which can remove over 90% of all the mercury if installed properly. While this legislation is a step in the right direction, further action is needed to encourage health care facilities to eliminate the use of mercury in health care practices to ensure that no mercury enters the environment from dental and medical offices.
The Oregon Center for Environmental Health’s “Health Care Without Harm” campaign is working to eliminate mercury in hospitals by promoting safer alternatives. In 2006 Kaiser Permanente Northwest Region, Legacy Heath System, and Providence St. Vincent Medical Center received the “Making Medicine Mercury-Free” Award from the Hospitals for a Healthy Environment for virtually eliminating mercury devices from their facilities and discontinuing the purchase of new mercury-containing devices. Also in 2006 Oregon Health & Science University, Providence Newberg Hospital and Providence St. Vincent Medical Center were recipients of the Partners for Change Award from the Hospitals for a Healthy Environment for the significant progress they have made toward eliminating mercury from their facilities.
Expand and develop programs to safely collect and recycle mercury-containing products. In the past few years, Oregon DEQ has implemented, funded, and co-sponsored a number of programs to collect and safely manage mercury thermostats, thermometers, fluorescent light tubes, and auto switches. These programs need to be expanded and continually evaluated to ensure that mercury-containing products are safely collected and recycled. The increasing use of energy-efficient compact fluorescent light bulbs (CFLs) necessitates the quick implementation of an effective recycling program to avoid the accumulation of mercury from CFLs in our solid waste management systems.*
Develop scientifically based regional fish-consumption guidelines. The amount of fish eaten varies geographically and among different populations. Data demonstrate that some populations in Oregon consume more fish than the current EPA reference dose.45 Oregon DEQ—in partnership with the EPA, the Confederated Tribes of the Umatilla Indian Reservation and other community members—is in the process of reviewing Oregon fish consumption rates to determine appropriate fish consumption guidelines. Oregon needs to adopt appropriate, regional guidelines for fish consumption that protect populations at risk from eating contaminated seafood and fish from local and commercial sources.
Reducing Your Exposure to Mercury
Avoid fish high in mercury. Fish species that are known to be high in mercury are long-lived, large predators. Examples include king mackerel, tilefish, swordfish, orange roughy, and marlin. Limit consumption of tuna, especially steaks and canned ‘white’ albacore. In a recent study, 100% of tested canned tuna contained methylmercury.46 The range of contamination was wide, but a pregnant or nursing woman could only eat one can of the most contaminated tuna every 98 days without risking damage to her baby. Lower-mercury choices include wild salmon, sardines, anchovies, Atlantic herring, Dungeness crab, Pacific cod, Alaskan black cod, farmed striped bass, tilapia, farmed catfish, clams, mussels, and Pacific oysters.
You can find additional guidance on fish choices at the following websites:
- Oregon Department of Human Services, An Expectant Mother’s Guide to Eating Fish in Oregon.
- Environmental Defense, Oceans Alive: Best and Worst Seafood
- Environmental Working Group, Mercury in Seafood (includes Tuna Calculator)
Exercise caution when consuming sport-caught fish. If you eat fish caught in local rivers and streams, check the Oregon Department of Human Service’s fish advisories for specific guidance on Oregon water bodies or coastal waters. Almost 20% of Oregon’s waterways are under fish advisories due to contamination from persistent bioaccumulative pollutants, including mercury. These advisories include fish in the Cottage Grove Reservoir near Eugene, fish in the Coast Fork and entire main stem of the Willamette River and fish throughout eastern Oregon. Fish and shellfish consumption advisories are available here.
Avoid purchasing and using consumer products that contain mercury. The most common household items that may contain mercury include thermostats, barometers, manometers and thermometers.* Buy digital or mechanical thermostats and digital or alcohol-based thermometers, all of which are free of mercury. Encourage local businesses to carry mercury-free items whenever possible and to offer recycling for mercury-containing products in their stores.
Make sure your medicines are free of mercury. Some home remedies, including some Hispanic folk remedies (“grieta”) and Ayurvedic herbal preparations and immunizations can contain mercury. Look at ingredient lists, talk to your doctor, and avoid folk remedies and other medicines that contain mercury.
Dispose of mercury-containing products responsibly. Keep mercury out of landfills and incinerators by recycling batteries and mercury-containing wall-mounted thermostats. Exchange mercury-containing thermometers. Recycle compact fluorescent lightbulbs (CFLs) appropriately. While compact fluorescent light bulbs do contain a small amount of mercury, they reduce overall mercury emissions because they are far more efficient than incandescent bulbs and reduce the amount of coal burned to power our homes.
Choose green energy. A primary source of mercury in the environment is pollution from coal-fired power plants. Although Oregon only has one coal power plant, one-third of our electricity is generated by coal-fired power plants located here and in nearby states. By choosing your power utility’s green energy option, you can help reduce mercury and other air pollutants across the West.
Ask your elected officials to take action on mercury reduction policies. Lobby your elected officials to strengthen regulations on industrial releases of mercury and to fund clean-up of Oregon’s abandoned mines which continue to leak mercury.
* It is important to note that although CFLs do contain small quantities of mercury, they are far more energy efficient than incandescent lights. CFLs significantly reduce the amount of mercury released into the environment because they reduce the amount of energy generated by coal-fired power plants, the main source of mercury in the United States.
* In 2002, the sale of mercury-containing fever thermometers was banned in Oregon. Mercury-containing fever thermometers are still available for purchase in other states.
