Mercury

Ever wonder where the old saying "mad as a hatter" came from? Or, what made the Mad Hatter in "Alice's Adventures in Wonderland" (Lewis Carroll's 1865 classic) "mad"? Why did these hat makers or "hatters" have a reputation for strange, unpredictable behavior? The answer: they were suffering from mercury poisoning.

In the 1800s, mercury nitrate was used in the felting process. Exposure to the chemical affected the workers nervous systems, causing them to display symptoms of chronic mercury poisoning: excitability, mental instability, a tendency to weep, fine tremors of the hands and feet, and personality changes.

Mercury is no longer used in the felting process, but it is still a common ingredient in many household and workplace items. If these items are broken or managed improperly, they can release mercury vapors into our homes, workplace, and environment.

Learn to identify mercury-containing products around the home!

The following are known to often contain mercury:

• Thermostats with mercury tilt switches (example)
• Various switches and relays in electronics (e.g., LA Gear® children's shoes manufactured before 1997 with flashing lights in the soles, automatic or tilt shut off steam irons and curling irons, some laptop computer screens/covers, computer hard drives, some cellular/portable phones, the fuel gauge in some riding lawnmowers, sump pumps, some automobile hood and trunk lights, automobile anti-lock brakes, and some appliance lid lights)
• Mercuric oxide batteries (primarily used in hearing aids, cameras, and watches)
• Alkaline batteries (pre-1992 have much more mercury than newer ones)
• All fluorescent lamps
• All high intensity discharge (HID) lamps (e.g., mercury vapor, metal halide, high pressure sodium 'neon' lamps, black lights, "bug zappers")
• Thermometers with characteristic silver bulbs
• Gauges (e.g., barometers, blood pressure)
• Latex paint manufactured before 1990
• Oil-based paint (check the label)
• Dental "silver" amalgam (example)
• Some automotive headlights (those that shine with a bluish tint)
• Manometers (used for carburetor synchronization in motorcycles, cars, and boats)
• Pesticides (prior to 1976)
• Pilot light flame sensors (gas dryers, ranges, ovens, refrigerators, space heaters- but not gas water heaters)
• Mercurochrome®/merbromin (topical disinfectant) (example)
• Thimerosal/Tincture of Merthiolate (topical disinfectant and preservative found in some nasal sprays and older contact lens solutions)
• Weight/counterweight in grandfather clocks
• Archery/crossbow dampers
• Jewelry (usually glass ampules made in Mexico)
• Spiritual/ritual use in some Caribbean/Hispanic communities
• Some greeting cards that light up or make noise
• Vintage toys (e.g., the Mercury Maze game)
• Some chemistry sets
• And some people have jars of elemental mercury (a silver liquid) just sitting around!

Workers in the health care field should be cautious around the following instruments and solutions since they often contain mercury:

• Gastrointestinal tubes (e.g., bougies, feeding tubes, cantor tubes, esophageal dilators)
• Various thermometers (incubators...) (example)
• Sphygmomanometers
• Pressure gauges (e.g., barometers, manometers, vacuum gauges, x-ray tubes, heating pad tilt switches)
• Pharmaceutical supplies (e.g., vaccines with thimerosal, early pregnancy kits with mercury containing preservatives, diuretics with mersalyl or phenlymercuric nitrate, Fixative B5)
• Batteries (e.g., alarms, defibrillators, hearing aids, pacemakers, ultrasound machines, ventilators)
• Electrical equipment (e.g. building security systems, fire alarm switch boxes)
• Dental "silver" amalgam

Why is mercury used in so many products?

Mercury has unique characteristics that make it the easiest material to use in various medical, industrial, and household devices. For example, mercury is the only metal that exists as a liquid at room temperature. It expands and contracts according to temperature changes, combines easily with other metals, and conducts electricity.

Fluorescent lights, for example, take advantage of many of its properties. When the light switch is turned on, the electrical current heats the mercury housed inside a thin tube within the bulb. Once heated, it expands to fill the tube, conducting electricity from one side of the tube to the other. The circuit is completed and the light turns on. When the switch is turned off, the mercury shrinks, disconnecting the circuit.

Before you buy, check what's inside!

Don't buy mercury-containing products unless absolutely necessary. Consult the following list for alternative products. If you see mercury-containing products used at your workplace, suggest alternatives. Reducing hazardous materials at work makes good business sense.

Common alternatives to mercury containing products:

Alternatives for the health care field

Mercury is present in "silver" dental fillings. There is much debate over whether it is a health concern for the patient.

A note on fluorescent and HID lights

Even though these lights contain mercury, the energy savings they deliver over incandescent bulbs saves tons of mercury air pollution that would be released from coal in coal burning power plants. Buying them is a good thing; just purchase lamps with green caps (indicating low-mercury) if possible and recycle the light at the end of its useful life.

Your thermostat: a small change will make a big difference

Do you have a mercury-containing thermostat? To find out, look behind the cover at about the 1 o'clock position (example). If there's a silver liquid inside a glass switch, it contains mercury. When it needs replacing install a digital, programmable thermostat. With a digital thermostat you'll not only reduce mercury pollution, but will save money and energy.

Health issues

Mercury affects the brain, spinal cord, kidneys, and liver. It affects the ability to feel, see, taste, and move. Long-term exposure to mercury can result in symptoms that get progressively worse and lead to personality changes, stupor, and coma.

Exposure to mercury can occur through inhalation, ingestion, or absorption through the skin. The most common routes are inhalation and ingestion.

Inhalation exposure commonly occurs when mercury vapors are inhaled while cleaning up a broken mercury-containing item. A few such incidents over the course of a lifetime may or may not affect your overall health. The outcome will depend on the individual, the dose received, and the exposure time.

The other common route of exposure is ingestion from eating contaminated fish. When mercury finds its way to a body of water, it settles into the sediment where bacteria converts to methyl mercury, its most dangerous form. It then moves to aquatic plants and small organisms that are eaten by fish. The fish, in turn, cannot metabolize or excrete the mercury, and it accumulates in their tissues. The level of mercury in the fish continues to rise over time as the fish consume more mercury-laden plants.

Mercury also increases in concentration as it passes through successive levels of the food web (i.e., as smaller fish are eaten by larger fish and other predators). The top predator in a food web can have up to 1 million times more mercury in its tissues than the concentration of the toxin in the water body.

This does not mean you should stop eating fish. But you may want to closely monitor your intake depending on the amount you eat, the source of the fish, and your health status.

Pregnant women should exercise extra caution as the fetus is highly susceptible to methyl mercury poisoning. Mercury can pass through the placenta, where it affects fetal development by preventing the brain and nervous system from developing normally. Affected children show lowered intelligence, impaired hearing, and poor coordination.

According to an article from a medical website, the FDA has recommended that pregnant women avoid shark, swordfish, king mackerel, and tilefish/ocean whitefish. The agency reported that these species carry the most risk since they are relatively long-lived and can accumulate large amounts of mercury in their tissues. For other cooked fish, the agency said that pregnant women could safely eat about two large servings (about 12 ounces), per week. Watchdog groups, however, argue that the FDA recommendations are not stringent enough.

(See Sean Martin, "Expectant Moms, Can the Fish," WebMD, April 12, 2001, http://content.health.msn.com/content/article/1728.77255)

How to see if you've been exposed

Ask your doctor to run a blood, urine, or hair test.

How to test for mercury contamination in the air

An environmental/industrial hygiene consulting firm can perform a test or you can buy a monitor to do it yourself. One source of mercury monitors can be reached at 800-827-4821, or on the Internet at www.mercuryvapor.com. Also check for additional sources under "environmental laboratories" in the yellow pages.

Prevent mercury spills!

The best way to avoid a spill is to replace mercury-containing products before they break! If the product is necessary and no mercury-free replacement exists, purchase a mercury spill kit to keep on hand in the event of a spill. One source of spill kits in Georgia is MWS at 770-953-8000. Do not leave children unattended near the device and try not to use it in a carpeted area. Mercury is much easier to clean up if spilled on a smooth surface rather than on a rug or carpet.

Tips for health care facilities

1. Hold a mercury thermometer exchange for employees and the public
2. Hold annual mercury training/spill/labeling programs
3. End the distribution of mercury thermometers to new parents and patients
4. Implement a mercury-free purchasing policy
5. Create a replacement plan and budget for the elimination of mercury-containing equipment
6. Collect all wastes from processes involving fixative B5 and designate a team to investigate the use of mercury-free alternatives
7. Develop a waste trap cleaning/recycling program

How to clean up a mercury spill

Even tiny mercury spills need to be thoroughly cleaned up. Never use a vacuum cleaner or a shop vac to clean up a mercury spill! Vacuums release mercury vapors into the air, which is exactly what you want to avoid. Instead, if a small spill (thermometer) occurs on a smooth surface, use two pieces of thick paper (such as index cards) to scoop all the tiny beads into a sealable, plastic container. If necessary, use an eye dropper to capture the mercury beads. Wipe the area with a damp sponge. If a spill occurs on a rug, carpet, or upholstery, it is best to remove the affected item since mercury can split into tiny beads and never be detected.

After clean up and/or removal, place everything that has been in contact with mercury in marked plastic containers and call 1-800-CLEANUP or go to www.CLEANUP.org for a recycling location.

For larger spills, place a bucket over the area if possible (to reduce vapors), ventilate the room, and leave the area to contact an environmental company located in the phone book under "environmental services." If contact with mercury occurs, call the Georgia Poison Center at 404-616-9000 or 800-282-5846.

How to dispose of mercury

Recycling is the best method for managing mercury. For recycling options, call 1-800-CLEANUP, go to www.CLEANUP.org, or contact your local recycling coordinator.

Household Hazardous Waste

Radon

Home Landscaping

Resources for Students and Teachers

Overview of Mercury Policy in the U.S.