Angela Garcia, age 15, of Rutland, Vt., for her question:

WHAT IS HEXACHLOROPHENE?

Hexachlorophene is a chemical antibacterial ingredient that used to be used in deodorants and antiperspirants. But the product hasn't been in general use since 1972 when the United States Food and Drug Administration restricted its use in cosmetics after research showed that it could damage the nervous system.

Common antibacterial ingredients are currently being used instead of hexachlorophene. They include a variety of zinc salts. Most antiperspirants also contain some type of aluminum salt that acts as an astringent to decrease perspiration.

Perspiration itself, by the way, has no odor. But sometimes underarm perspiration reacts with bacteria on the skin and causes an odor. Deodorants reduce the growth of bacteria.