A mercury fever thermometer is a small glass tube that contains liquid elemental mercury--a silvery white substance. Glass thermometers that contain a red or blue liquid are alcohol thermometers and contain no mercury. Another, not yet in wide distribution, contains galinstan, a mixture of gallium, indium and tin that is similar to mercury in appearance. These thermometers are mercury-free, however, and are generally marked as such.
Mercury is a toxic substance that can harm both humans and wildlife. When products that contain mercury break, the mercury can evaporate, creating a risk of dangerous exposures to mercury vapor in indoor air. Moreover, mercury that volatilizes when products such as thermometers break in the home or in the waste disposal system enters the environment and can be deposited in lakes and rivers, where it can be transformed into highly toxic methylmercury. Methylmercury accumulates in the food chain, so that a very small amount of mercury in a lake can lead to dangerous levels of methylmercury in fish. People who consume large amounts of fish are at risk of adverse effects of methylmercury on the nervous system. Because the developing nervous system is more vulnerable to mercury toxicity, fetuses exposed to methylmercury through their mothers consumption of fish and individuals who eat large amounts of fish that have high mercury contamination are particularly at risk of adverse effects. Mercury is the most frequent basis for advisories about the potential dangers of consuming fish, represented in 60 percent of all water bodies with fish consumption advisories. Forty states have advisories for mercury in one or more water bodies, and eleven states have issued statewide mercury advisories.
Do fever thermometers really contain enough mercury to affect the environment? (back to Top)
While the amount of mercury in an individual thermometer may seem small, the total amount that is released to the environment as the result of thermometer use is significant. Fever thermometers containing an estimated 17 tons of mercury are discarded annually to municipal solid waste in the United States, making fever thermometers the largest single source of mercury to municipal solid waste. Combustion of municipal solid waste is the second largest source of mercury to the environment in the United States; the fourth largest source of mercury to the environment is combustion of medical wastes. These two categories together account for nearly one-third of the mercury released to the atmosphere.
Does a broken fever thermometer really pose a health risk to the consumer? (back to Top)
Breaking one fever thermometer is unlikely to threaten the health of the consumer in most circumstances, but under some conditions, the mercury from a fever thermometer can seriously harm the consumer and his or her family. If the consumer either fails to clean up mercury because he or she is unaware that it has broken or because it is difficult to gain access to the mercury (for instance because it has seeped through a carpet), then all of the mercury will eventually volatilize and could reach dangerous levels in indoor air. Moreover, if the consumer attempts to clean up a mercury spill with a vacuum cleaner, of if the mercury is heated for some reason, the mercury will vaporize quickly, increasing the risk. The danger of significant mercury exposure is greatest in a small, poorly-ventilated room.
The medical literature contains several cases of serious illness and even death resulting from exposure to mercury from fever thermometers. Most, but not all, of these cases involve young children, who are known to be most susceptible to the effects of mercury. (see below)
It is also common for children to break fever thermometers in their mouths. Mercury that is swallowed in such cases poses low risk in comparison with the risk of breathing mercury vapor. The mercury passes through the body without being absorbed, but then it enters the waste water system and can reach the environment.
What should you do with a broken mercury thermometer? (back to Top)
Even small mercury spills must be cleaned up properly. Never use a vacuum cleaner, shop vac, or broom to clean up mercury! A vacuum will put the mercury into the air, and a broom will just spread the mercury, making it harder to collect. If a thermometer breaks on a smooth surface, use two stiff pieces of paper to scoop all the tiny beads into a sealable, plastic container. If necessary, use an eye dropper to capture the beads of mercury. Wipe area with a damp sponge. All cleanup material, including paper, eye dropper and sponge, as well as any contaminated rug or portion of carpet must be properly disposed with the mercury. Put everything in marked plastic containers and take them to a local mercury recycling site. Replace the broken thermometer with a non-mercury thermometer.
What are the alternatives to mercury thermometers? (back to Top)
Several types of non-mercury thermometers are available commercially. These include:
All of the above thermometers, like mercury thermometers, can be used to take oral, rectal or axillary (armpit) temperature. Digital electronic fever thermometers are readily available at retailers. There are also digital basal thermometers for family planning that can be used instead of mercury basal thermometers. Alcohol thermometers are currently less easy to find at retailers. Galinstan thermometers have recently been approved by the Food and Drug Administration.
Are non-mercury fever thermometers adequate diagnostic tools? (back to Top)
A recent statement by the American Medical Association reviewed the benefits and drawbacks of the more readily-available types of fever thermometers:
There may be rare instances when a mercury thermometer may be preferred for some types of patients. Patients who are concerned about whether non-mercury thermometers are adequate for a particular circumstance should consult their physicians.
What are the risks that an alternative thermometer could poison the user? (back to Top)
There is no known or anticipated risk.
What are the environmental consequences of non-mercury thermometers? (back to Top)
The known environmental damages caused by alternative thermometers are significantly less than those presented by mercury thermometers. A typical mercury thermometer contains approximately one-half gram of mercury (500 milligrams), but larger thermometers can contain as much as three grams. The primary environmental concern arising from use of alternative thermometers relates to the disposal of button cell batteries used in digital electronic or ear canal thermometers. Button cell batteries used in digital thermometers contain significantly less mercury than a mercury thermometer--roughly 3.5 to 11 milligrams of mercury per battery.
When either a mercury thermometer or a button cell battery is thrown away and ends up in an incinerator, much of the mercury that it contains is likely to be emitted to the atmosphere. Similarly, if an intact thermometer or battery goes to a municipal waste landfill, most of the mercury contained in either product is likely to be buried in the landfill. However, a mercury thermometer that breaks in the home, or that breaks in the solid waste system prior to burial in a landfill, will release significantly more of its mercury than will a button cell battery.
Contact: Alexis Cain, U.S. Environmental Protection Agency, Region 5 (back to Top)
This Page created June 11, 1998
Revised: September 24, 2001