Mercury

Overview

Mercury is a chemical element (Hg), a heavy metal that is unique in that it is commonly used in liquid form. Mercury has long been used in healthcare in a variety of functions, including in measuring instrumentation and electronic equipment, as an antibacterial or preservative, and in fixatives and stains used in pathology labs. The concern with using mercury is that it is a highly potent neurotoxin that can cause a range of different health impacts. There are three primary forms of mercury. The forms have different properties, and therefore present different types of exposure risks:

• Metallic liquid mercury: Like any other liquid, mercury evaporates.  Once in the vapor state, it passes very efficiently into the lungs (about 80% of what is inhaled stays in the body).  Some of it is then converted to inorganic salts.  The rest dissolves in fatty tissue, and can enter the central nervous system, where it can cause neurological problems ranging from subtle to severe.  In contrast, metallic liquid mercury does not pass very readily though skin, nor is it absorbed well from the digestive tract.
• Inorganic mercury salts: This form of mercury is highly toxic.  If ingested, about 10% will pass into the body through the digestive tract lining.  Much of that will collect in the kidneys and can cause severe damage there.  But inorganic mercury salts do not dissolve well in fat, and are not absorbed easily into cells.
• Organic mercury compounds: This form of mercury is fat-soluble, and passes easily into the body (90 - 95% in the case of methylmercury) from the digestive tract.  They will be distributed throughout the body, and will cross the placental barrier, passing from mother to unborn child where they can cause significant neurodevelopmental impacts.

The US EPA website provides a concise summary of health effects from exposure to each form of mercury, with links to more detailed references.

Mercury is a persistent, bioaccumulative and toxic (PBT) chemical and is on EPA's Priority Chemicals List , which is a list of 31 chemicals targeted for reduction or elimination.  Persistent refers to the fact that mercury doesn’t break down in the environment, it doesn’t go away. Bioaccumulative refers to the fact that mercury builds up in the food chain and persists in muscle  tissue when ingested. Toxic refers to the range of different neurodevelopmental and harmful effects mercury can have in the body.

Human Exposure to Mercury

The primary route of human exposure to mercury is through the consumption of mercury-contaminated fish and seafood. Different sources of industrial pollution release mercury to air where it falls into bodies of water and is transformed into methylmercury. Fish ingest the methylmercury and it makes its way up the food chain. Humans eat contaminated fish, and methylmercury enter the bloodstream. Methylmercury can cross the blood-brain barrier and cross the placenta, impacting fetal development. Data from the Centers for Disease Control and Prevention (CDC) show that about 10 percent of all women of childbearing age have blood methylmercury levels above the dose that may put their fetus at risk for adverse neurological effects (CDC, 2001). EPA's Fish Advisories webpage can provide information on current fish advisories in different states for mercury. Learn more about safer fish to eat with the Environmental Working Group's Safe Fish List.

Healthcare's Mercury Contribution

In 1997, medical waste incineration was listed as the third largest source of mercury to the environment (EPA, 1997). At the time, healthcare facilities were routinely disposing of waste and materials contaminated with mercury and sending these wastes for disposal through medical waste incineration. Healthcare-generated mercury was also being disposed of to the solid waste stream where it entered the environment through landfills or municipal waste incinerators, and through wastewater effluent. Healthcare also contributes to mercury pollution through its use of electricity--much of which is fuled by coal-fired power plants, the #1 source of mercury to the environment. In 1998, recognizing healthcare's impact, the American Hospital Association and the Environmental Protection Agency signed a landmark Memorandum of Understanding calling on the nation's hospitals to voluntarily eliminate mercury, reduce other persistent bioaccumulative toxic (PBT) chemicals where possible and to reduce the volume of hospital waste.  The MOU set a goal of complete mercury elimination in health care by 2005.  The sector has not yet accomplished this goal but continues to make progress.

The healthcare sector utilizes mercury in a variety of different devices and products including:

• Clinical Devices: Including (but not limited to) fever thermometers, sphygmomanometers (blood pressure devices), esophageal bougies and dilators, Cantor tubes and Miller-Abbott tubes. Also used in dental amalgam.
• Facility Equipment: Including (but not limited to) switches, relays, thermostats, fluorescent lamps and light bulbs, and batteries.
• Lab: Including (but not limited to) fixatives and stains used for epdiemiology in histopathology labs (such as B5, Zenker's Solution and Gram iodine stains), and laboratory equipment.
• Pharmacy: Mercury is used in the preservative thimerosal (59% mercury by weight) which is used in vaccines and other pharmaceutical formulations. See Premier's comprehensive list of mercury in pharmaceuticals here.
• Other: Mercury has been found in the fixer solution for non-digital x-ray technology, in trace amounts in cleaning products and bleach, and in electronics such as computer and laptop screens, to name a few.

See Mercury Elimination Tools & Resources for available mercury assessment tools.

Next Steps

Hospitals across the United States--and around the world--are finding ways to utilize alternative devices, products and chemicals that no longer contain mercury, and are finding it can actually save the facility money through decreased hazardous waste disposal costs, avoided spills and lost revenue from closed patient areas during spills, and even the purchase of mercury spill kits.

Learn more about Elimination Strategies for Mercury

See additional Mercury Elimination Tools & Resources