A. Mercury is a naturally-occurring toxic element that may be found in any of three forms – elemental (metallic), inorganic, and organic. In its elemental form, mercury is a shiny, silver-white, dense, odorless liquid metal used in items such as thermometers and electrical switches. When it evaporates, elemental mercury forms a colorless, odorless gas. Mercury can combine with other elements to form inorganic compounds. Methyl mercury, an organic mercury compound and the form that poses the greatest threat to humans and the environment, is created when biological processes alter elemental or inorganic mercury.

A. Mercury is a big deal because it is a persistent, bioaccumulative toxin (PBT) and one that is highly mobile. Short-term high-level exposure to mercury (generally vapors or liquid) can result in central nervous system impairment, kidney damage and failure, gastrointestinal damage, cardiovascular collapse, shock, and death. Even a few small drops of elemental mercury can raise air concentrations to levels that may be dangerous to human health. Mercury and its vapor are very difficult to remove from areas in which it has been spilled and may remain for months, continually exposing those in the environment. Chronic exposure to relatively high levels can result in effects on the cardiovascular and immune systems, but the major concern is mercury’s neurotoxicity. Additionally, it is absorbed a lot faster than it can be removed. Half-life in the human body is estimated to range between 44 and 80 days. Worse yet, methyl mercury readily crosses the placental barriers, placing our children at great risk.

A. Yes. Wildlife (including fish) are most often exposed to mercury in its methyl mercury form. Wildlife exposed to mercury may experience death, reduced reproductive success, impaired growth and development, or behavioral abnormalities. Alarmingly, reproductive damage can occur at mercury levels far lower than those which indicate toxicity. Top-level predator fish and top-level avian and mammalian predators, such as eagles, loons, osprey, mink, and otter, are more likely to be at risk for mercury exposure than organisms existing lower on the food chain, due to the processes of bioaccumulation and biomagnification.

A. Bioaccumulation results when organisms take in contaminants faster than their bodies can remove them, leading to a gradual accumulation of contaminants over time.

A. Biomagnification is the incremental increase in contaminant concentration at each level in the food chain. As a result, upper-level predators, such as bass, pike, swordfish, and shark, have greater methyl mercury concentrations than their lower-level prey. Upper-level predatory fish can acquire methylmercury concentrations up to 10 million times greater than the surrounding waters.(1)

A. Human exposure to mercury can result from:

• Inhalation of mercury fumes.
• Absorption through the skin. (A common type of skin exposure is improperly cleaning up broken glass thermometers containing mercury.)
• Ingestion of objects that contain mercury. For example, small children may eat batteries that contain mercury. Small amounts of mercury released from broken high power lights and fluorescent tubes may also be ingested accidentally.
• Ingestion of foods (especially fish) or water that has been contaminated by mercury. Mercury is absorbed by fish through their gills. Mercury also makes its way up the food chain when fish eat plankton or smaller fish that are contaminated. Fish that are commonly found with high levels of mercury include shark, swordfish, and large tuna. The U.S. Food and Drug Administration has set a 1 ppm (part per million) limit on the amount of mercury in fish intended for human consumption.

A. Just about everyone, but mostly fetuses and developing children. Obviously, people who use mercury products in their home, school, or work are at risk from mercury exposure. However, most of the health risk from mercury exposure is due to methylmercury exposure from fish consumption. In 2002, 44 states issued fish consumption advisories aimed at protecting people from mercury contamination. Many factors determine the level of risk from mercury exposure, including the dose, duration, and type of contact. Developing embryos and young children are a high risk population. Methyl mercury in the mother’s body may enter unborn children and breast-fed infants. Children under 15 are at higher risk than adults because of their still-developing nervous system and lower body weight relative to amount of food consumed. Exposure and health risks may be determined by measuring the amounts of mercury in blood, urine, breast milk, and hair. Over time, the body can slowly rid itself of contamination. Adults who consume an unusually large amount of contaminated fish on a regular basis, such as subsistence fisherman, may also be at risk.

A. Current Sources:

Metallic mercury is used in gold mining and in the production of chlorine gas and caustic soda. It is also a component of any thermometers, barometers, electrical switches, and batteries. Additionally, approximately 50% of the content of dental fillings, crowns, etc., is mercury. Some other products containing metallic mercury include:

• Cathode tubes
• Calculators and small appliances
• Medical laboratory chemicals
• Production of urethane polymers for plastics
• Mercury vapor lamps and advertising signs
• Hearing aides
• Common household cleaners

Inorganic mercury is used in some skin-lightening creams, topical antiseptics and disinfectants, and antibacterials. Formerly, it was an ingredient in laxatives, worming medications, and teething powders. It has been used in color paints and tattoo dyes, as well.

Methyl mercury was used as a fungicide until the 1970s and as an antifungal in paints until 1991.

To view more details about products containing mercury, click here.

A. Not really. Substitutes for mercury abound. Instead of mercury:

• lithium, nickel-cadmium, zinc, or indium compounds can be used in batteries;
• diaphragm and membrane cells can be used to produce chlorine and caustic soda;
• dental amalgams (crowns, filings, etc.) can be made of ceramic;
• latex paint fungicides are now made with organic compounds;
• thermometers, barometers, etc., can utilize digital technology.

A. U.S. government summaries have indicated no apparent health hazard to the general population, but admit a need for further studies on subtle behavioral and immune system effects and potentially sensitive populations, such as children under 6, pregnant women, persons with impaired kidney function, and persons with hypersensitivity to metals. At any rate, removal of already emplaced amalgams can put the person at greater risk, if done improperly. For the latest on dental amalgam hazards, click here.

A. Unfortunately, the majority of products containing mercury are disposed in waste systems not equipped to handle mercury. In fact, approximately 1/3 of mercury pollution in the U.S. is released by waste incinerators burning mercury-tainted trash. Wind can carry airborne mercury great distances before it is deposited on land and water, primarily by rain and snow, contaminating pristine waters hundreds of miles from the nearest mercury source.

A. Mercury is persistent, mobile, and bioaccumulative. Most of the mercury found in the environment is inorganic mercury that can enter the air from several sources. Incineration of mercury-containing municipal and medical waste and natural processes such as ore erosion and volcanic activity release mercury into the atmosphere. Airborne mercury is then deposited in rain or snow. Microscopic organisms metabolize the mercury and release methyl mercury. Methylmercury is quickly taken up into higher organisms through the food chain and is retained in their bodies. It reaches the highest levels in large predatory fish and in birds and mammals that consume fish. Levels of methyl mercury in fish are typically hundreds of thousands times greater than those levels in surrounding water.

A. The Environmental Protection Agency has set a mercury limit for drinking water of 2 ppb (parts per billion). The EPA also recommends that the level of mercury in rivers, lakes, and streams be no greater than 0.144 ppb. Additionally, the EPA’s Office of Water has issued guidelines for fish consumption advisories for methyl mercury. The U.S. Food and Drug Administration has set a maximum methyl mercury level for seafood of 1 ppm.

Sources:
(1) U.S. Environmental Protection Agency. Office of Water. “Mercury Update: Impact on Fish Advisories.” June 2001. 30 June 2003 <http://www.epa.gov/ost/fishadvice/mercupd.pdf>.
(2) “Public Health Statement for Mercury.” March 1999. Agency for Toxic Substances and Disease Registry. 30 June 2003 <http://www.atsdr.cdc.gov/toxprofiles/phs46.html>.