About mercury

Mercury is a naturally occurring metal found in the environment. It's a liquid at room temperature and easily evaporates into the atmosphere where we can breathe it in. Mercury is among a group of pollutants called persistent bio-accumulative toxins, or PBTs. These toxins persist in the environment and don't break down or go away.

Mercury-Free Colorado Campaign

Recycle compact fluorescent lamps (CFLs), health and toxicity, fish consumption advisories, a closer look at mercury in homes, schools, hospitals, and dental offices.

Human exposure to mercury

When mercury is deposited in waterways, bacteria convert it to methylmercury. Methylmercury builds up in the tissue of fish, which may then be eaten by wildlife (e.g., eagles, osprey, common loons, river otters, minks) and by people. Because mercury is tightly bound to the fish muscle tissue, there is no method of cooking or preparation that will remove or reduce mercury once it's in fish.

This doesn't mean you should stop eating fish. It's a good source of protein and is low in saturated fat. You can still get the benefits of eating fish by using moderation in how much you eat.

The two organ systems most likely affected by methylmercury are the central nervous system and the kidneys. The groups most vulnerable to the effects of mercury toxicity are women who are pregnant or may become pregnant, nursing mothers and young children. The most significant concerns about chronic exposure to low concentrations of methylmercury in fish are for neurological effects in children and developing fetuses.

Although human exposure to mercury occurs most frequently through eating contaminated fish, other human exposures to mercury can occur. People have been exposed to mercury from inhaling mercury vapors from broken fluorescent lamps, gas regulators or even home fever thermometers. There have been cases of mercury exposures from accidental swallowing, but these cases are rare.

Learn more about exposure to mercury

Mercury toxicity

Mercury (Hg) is a naturally occurring metal found throughout the environment. It's a liquid at room temperature, combines easily with other metals, and expands and contracts evenly with temperature changes.

Because of these properties, mercury has been used in many household, medical and industrial products. Although it performs many useful functions in our workplaces and homes, mercury is toxic and can impair our health. It's a potent neurotoxin, meaning it interferes with the way nerve cells function. Mercury poisoning causes a decreased ability to see, hear, talk and walk. It can cause personality changes, depression, irritability, nervousness and the inability to concentrate. It also can cause damage to the brain, kidneys and lungs.

Mercury is a particularly serious problem for pregnant women and children. Fetuses and young children suffer the greatest risk because their nervous systems are still developing. They are four to five times more sensitive to mercury than adults.

Mercury in the environment

Mercury can be released into the environment from natural sources, such as volcanic and geothermal activity, marine environments or forest fires, or it can be released from man-made sources like coal-fired power plants and other industrial activities.

Recent studies suggest that human activity contributes 50 to 70 percent of the mercury in the environment globally (Office of Air Quality and Standards Report to Congress, 1997). Once it enters the environment, it circulates in and out of the atmosphere until it ends up in the bottoms of lakes and oceans where it is transformed by bacteria into a form that can accumulate in fish tissue.

Mercury is among a group of pollutants called persistent bio-accumulative toxins, or PBTs. These pollutants "persist" in the environment, meaning that they don’t break down or go away. Mercury can’t be destroyed or combusted and it doesn’t degrade.

Mercury in hospitals

Mercury is used in many instruments and products in the medical setting because of its uniform response to temperature and pressure changes. Mercury is used in sphygmomanometers, laboratory and patient care thermometers, and gastrointestinal devices. Mercury compounds also are used in preservatives, fixatives and reagents. Mercury from medical applications can enter the environment through sewers, spills and land disposal of trash.

Practice Greenhealth is designed to help hospitals improve their environmental performance. Through this program, health care professionals are educated about mercury reduction and pollution prevention opportunities. Practice Green health provides a wide range of tools and technical resources.

Health Care Without Harm and the World Health Organization are advocating for the virtual elimination of mercury-based thermometers and sphygmomanometers and their substitution with accurate, economically viable alternatives.

Instruments and products used in hospitals that may contain mercury

  • Thermometers:
    • Body temperature thermometers.
    • Clerget sugar test thermometers.
    • Heating and cooling system thermometers.
    • Incubator/water bath thermometers.
    • Minimum/maximum temperature thermometers.
    • National Institute of Standards and Technology calibration thermometers.
    • Tapered bulb (armored) thermometers.
  • Sphygmomanometers.
  • Gastrointestinal tubes:
    • Cantor tubes.
    • Esophageal dilators (bougie tubes).
    • Feeding tubes.
    • Miller Abbott tubes.
  • Dental amalgam.
  • Pharmaceutical supplies.
  • Contact lens solutions and other ophthalmic products containing thimerosal, phenylmercuric nitrate.
  • Diuretics with mersalyl and mercury salts.
  • Early pregnancy test kits with mercury-containing preservative.
  • Merbromin/water solution.
  • Nasal spray with thimerosal, phenylmercuric acetate or phenylmercuric nitrate.
  • Vaccines with thimerosal (primarily in haemophilus, hepatitis, rabies, tetanus, influenza, diphtheria and pertussis vaccines).
  • Cleaners and degreasers with mercury-contaminated caustic soda or chlorine.
  • Batteries (medical use):
    • Alarms.
    • Blood analyzers.
    • Defibrillators.
    • Hearing aids.
    • Meters.
    • Monitors.
    • Pacemakers.
    • Pumps.
    • Scales.
    • Telemetry transmitters.
    • Ultrasound.
    • Ventilators.
  • Batteries (non-medical use).
  • Lamps:
    • Fluorescent.
    • Germicidal.
    • High-intensity discharge (high pressure sodium, mercury vapor, metal halide).
    • Ultraviolet.
  • Electrical equipment:
    • Tilt switches.
    • Float control.
    • Septic tanks.
    • Sump pumps.
  • Thermostats (non-digital).
  • Pressure gauges:
    • Barometers.
    • Manometers.
  • Vacuum gauges.


Disposal options

How mercury from a business is regulated