Types of thermometers

If you're over 30, you may not recognize all the temperature-taking gadgets shown here. On the far left is a plastic strip with liquid crystals that react to heat. Moving clockwise, the others are a digital pacifier thermometer, a tympanic (ear) thermometer, a regular digital thermometer and a glass oral thermometer that contains a mercury substitute.

You probably remember glass mercury thermometers from your childhood. When broken or thrown away, these thermometers release mercury, a toxin that pollutes the environment and, in large amounts, causes brain damage. If you still have an old mercury thermometer, ask your doctor how to dispose of it safely.