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A fever can be a sign of an infection or other medical condition, so it is useful to check body temperature with a thermometer. Temperatures can be checked in the mouth, rectum, armpit, and ear as well as across the forehead. Thermometers use a variety of technologies to measure body temperature. The oldest technology is the mercury-in-glass thermometer. Newer technologies include non-mercury liquids-in-glass as well as digital and electronic devices that use sensors to measure temperature. Thermometers that check body temperature in the ear, across the forehead, or have a digital display do not contain mercury. The EPA recommends the use of mercury-free thermometers but it does not endorse any specific brand and suggests choosing a thermometer that is easy to use and read. A recent study found that the most accurate way to measure body temperature is with a rectal thermometer. However, the authors of the study say that when the rectal route is impractical or should be avoided, electronic thermometers that are placed in the mouth or in the ear are reasonable alternatives.
Potentially harmful effects from broken thermometers vary depending on the type of thermometer. The most concerning are mercury-containing thermometers. The least concerning are the digital/electronic thermometers because they contain no potentially hazardous liquids that can spill if broken. However, many of the electronic thermometers contain button cell batteries which can be very harmful if swallowed. If a battery is swallowed, contact the battery ingestion hotline at 800-498-8666.
Common to all the liquid-in-glass thermometers is the potential for injury from the broken glass. Studies of children in emergency rooms have noted injury to the mouth, rectum, and ear from broken thermometer glass. Otherwise the potential toxicity from these broken thermometers depends on the type of liquid used.
If you have a liquid-in-glass thermometer, it is important to be able to tell if it contains mercury. A few simple steps can help. If the liquid is not silver in color, it does not contain mercury. If the liquid is silver in color it might be mercury. Spilled mercury has a characteristic appearance. It is a dense, shiny, fast-moving liquid metal that can break up into little balls that reform when pushed together. But not all thermometers with silver liquid contain mercury. There are liquid-in-glass thermometers that contain a non-mercury silver substance (Galinstan®) that, according to its maker, is not toxic when swallowed because it passes through the digestive system without effect. Inhalation is also not a concern because there is no absorption through the lungs. If the thermometer has silver liquid and is not labeled as “mercury-free,” assume it contains mercury.
The non-silver liquid-in-glass thermometers typically contain a colored alcohol. Contact with the skin or inside the mouth could cause minor irritation or a burning sensation that should resolve quickly. If the liquid spills, rinse off the skin or rinse out the mouth with water. If the liquid gets in the eye, prevent irritation by irrigating the eye with water for 15 to 20 minutes, then call Poison Control.
Mercury can be toxic in certain situations. Most oral and rectal thermometers contain about 0.5-0.6 grams of mercury. Mercury is not absorbed through intact skin or from a healthy digestive tract in amounts that would cause toxic effects. Therefore, harmful effects would not be expected from swallowing or touching the small amount of mercury from a broken thermometer. However, skin irritation or contact dermatitis may develop.
The main health problems from mercury are from the vapors. These are produced at room temperature and especially when mercury is heated. The vapors can be inhaled and are absorbed into the body. The immediate effects of inhaling highly concentrated vapors include coughing, sore throat, difficulty breathing, chest pain, vomiting, and headache. An unexpected way to heat up mercury and produce vapors occurs when a vacuum cleaner is used to clean up a mercury spill. Never vacuum up mercury from a broken thermometer! If a mercury spill is not cleaned up right away, vapors will continue to be produced. These vapors might be in low concentrations that would not cause immediate effects, but repeated long-term exposure to vapors can cause problems such as shaking, difficulty walking, weakness, headaches, loss of appetite, gum inflammation, red skin, high blood pressure, rapid pulse, kidney damage, and personality changes.
Depending on the specific circumstances surrounding the broken mercury-containing thermometers, most cases can be managed safely at home; however, always contact Poison Control at 1-800-222-1222 for assistance.
Initial treatment following exposure to spilled mercury includes washing with soap and water if mercury came into contact with the skin and getting fresh air if the vapors are inhaled. Ingestion of small amounts of mercury usually do not need a specific treatment, but rinsing with water then spitting can help remove any mercury remaining in the mouth. For people with symptoms, special drugs can be given to help remove the mercury from the body.
Calls to Poison Control about mercury from broken thermometers are declining because of the availability of other types of thermometers. Although mercury is considered a highly toxic substance, the overall risk of toxicity from a broken mercury-containing thermometer is low when appropriate clean-up measures are taken.
The EPA recommends the following clean-up steps for broken mercury thermometers in your home.
- Have everyone else (including pets) leave the area; don't let anyone walk through the mercury on their way out. Open all windows and doors to the outside; shut all doors to other parts of the house.
- DO NOT allow children to help you clean up the spill.
- Mercury can be cleaned up easily from the following surfaces: wood, linoleum, tile, and most other hard, smooth surfaces.
- If a spill occurs on carpet, curtains, upholstery, or other absorbent surfaces, these contaminated items should be thrown away in accordance with the disposal means outlined below. Only cut and remove the affected portion of the contaminated carpet for disposal.
- Put on rubber, nitrile, or latex gloves.
- If there are any broken pieces of glass or sharp objects, pick them up with care. Place all broken objects on a paper towel. Fold the paper towel and seal it in a Zip-Lock style bag.
- Locate visible mercury beads. DO NOT use a vacuum cleaner or broom to clean up mercury. Use a squeegee or cardboard to gather mercury beads. Use slow sweeping motions to keep mercury from becoming uncontrollable. Take a flashlight, hold it at a low angle close to the floor and look for additional glistening beads of mercury that might be sticking to the surface or in small cracked areas on the surface. Note: Mercury can move surprising distances on hard, flat surfaces, so be sure to inspect the entire room.
- Use an eyedropper to collect the mercury beads. Slowly and carefully drop the mercury onto a damp paper towel. Place the paper towel in a Zip-Lock style bag and secure. DO NOT pour mercury down a drain.
- After you remove larger beads, put shaving cream on top of small paint brush and gently "dot" the affected area to pick up smaller hard-to-see beads. Alternatively, use sticky tape, such as duct tape, to pick up any remaining small glass fragments. Place the paint brush or duct tape in a zip lock bag and secure.
- Once all glass and mercury have been collected, Contact your local health or fire department for disposal guidance.
If someone has been exposed to a broken thermometer, contact Poison Control at 1-800-222-1222 for expert advice.
Karen D. Dominguez, PharmD
Certified Specialist in Poison Information
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