Chemistry, and Your Health: Antiseptics and Disinfectants: Same Thing?

Antiseptics and disinfectants are both used for
the same purpose: to kill bacteria. The difference between these two categories
of bacteria killers is where they are used. Antiseptics are used to kill
bacteria on living tissue, such as wounds. Disinfectants are used to kill
bacteria on inanimate objects. Some antiseptics, such as iodine and hydrogen
peroxide, operate by oxidizing and thus destroying compounds essential to the
normal functioning of the bacteria. A solution containing 3% hydrogen peroxide
dissolved in water is an antiseptic found in most pharmacies, and it is often
used to treat minor cuts and abrasions. A 2% solution of iodine dissolved
in alcohol, called tincture of iodine, is also generally available, and it is
used in a way similar to hydrogen peroxide. One disadvantage of the iodine
solution is that it stains the skin a yellow brown color.

 Oxidizing antiseptics are often regarded as
being too harsh. They may damage skin and other normal tissue, as well as kill
the bacteria. For this reason, they have been replaced in many products by
antiseptics derived from phenol. Water solutions of phenol, called carbolic
acid, were first introduced as hospital antiseptics in 1867 by the English
surgeon Joseph Lister. Before that time, antiseptics had not been used, and
very few patients survived even minor surgery because of postoperative
infections. These phenolic derivatives can often be recognized on ingredient
labels by the characteristic -ol ending of their names. Some examples are
thymol, eucalyptol, and eugenol.

 Because
disinfectants are used on inanimate objects, there is much less concern about
the damage they might do to living tissue, and many of them are oxidizing
agents. Sodium hypochlorite is one of the most widely used disinfectant compounds.
In 5% solutions, it is marketed as liquid laundry bleach. This solution is
an effective disinfectant for sinks, toilets, and similar fixtures. A
chemically similar compound called calcium hypochlorite is the active
ingredient in bleaching powder, and it is also used in hospitals as a
disinfectant for clothing and bedding. Chlorine gas and ozone gas are two
widely used, strong, oxidizing disinfectants. Their most well-known use is
water treatment; they are added in small quantities to municipal water supplies
to kill any harmful bacteria that may be present.