When products containing mercury break, the mercury can evaporate, creating a risk of dangerous exposures to mercury vapor in indoor air. Moreover, exposed mercury 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 a highly toxic version of mercury called methylmercury.

Occasionally serious illness and even death results 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.

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.

However, if the consumer fails to clean up mercury either 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 the mercury will eventually volatilize and might reach dangerous levels in indoor air. The risks increase if the consumer attempts to clean up a mercury spill with a vacuum cleaner, or if the mercury is heated for some reason. The danger of significant mercury exposure is greatest in a small, poorly-ventilated room.

Several types of non-mercury thermometers are available commercially. These include:

• digital electronic thermometers
• glass alcohol thermometers
• Glass gallium-indium-tin (galinstan) thermometers
• ear canal thermometers
• flexible "forehead thermometers"

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.

Both glass mercury thermometers and digital thermometers will give you an accurate reading. What's most important is that you choose a thermometer that's easy to use and read.

The newest thermometers available are ear thermometers that quickly and easily measure temperature inside the ear canal. They are still fairly expensive compared with glass and electronic models, and learning how to use them correctly takes some training. But they can be quick and relatively comfortable for children.

Forehead thermometers are convenient and comfortable to use, but they are not very accurate. They may be handy for quick screenings, but for exact readings use a glass thermometer or a digital one (3).

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.

The amount of mercury in an individual thermometer may seem small, but the total amount contained in thermometers is significant but thermometer manufacturer Becton Dickenson estimates that 4.3 tons of mercury are contained in the thermometers sold every year to hospitals and consumers in the United States.

Duluth, Minnesota and San Francisco have actually banned the sale of mercury fever thermometers, while other state and local government agencies around the United States are in the process – or considering – discouraging the use of mercury fever thermometer use by the general public.