ABC-TV's '20/20' tested two types of 'detox' foot pads and concluded that they didn't work. The products are claimed to remove toxins, restore 'balance' within the body, and boost energy. Users are instructed to apply them to the soles of the feet and leave them on overnight. In the morning, they claim, the pads will absorb toxins and turn muddy brown or black. The basic idea that toxins will be excreted through the skin clashes with what is known about human anatomy and physiology. Real detoxification of foreign substances takes place in the liver, which modifies their chemical structure to the can excreted by the kidneys, which filter them from the blood into the urine. Sweat glands in the feet can excrete water and some dissolved substances. However, its minor role in ridding the body of unwanted substances is not changed by applying foot pads. The 20/20 investigation found that (1) When used overnight, the pads darkened, but dropping distilled water on the pads produced the same dark colour; (2) Laboratory analysis of pads used by eight volunteers who showed no significant evidence of heavy metals or commonly used solvents; (3) When asked for tests that would show that their products really work the companies offered no valid scientific studies. Investigation by John Stossel, ABC News (11th April 2008)