Composition and safety

Older mothballs consisted primarily of naphthalene, but due to naphthalene's flammability, modern mothballs use 1,4-dichlorobenzene instead. Both of these ingredients have a strong, pungent odor often associated strongly with mothballs. Camphor, an insect repellent, can also be used in mothballs.

Both chemicals kill moths and moth larvae with the vapor. Both naphthalene and para-dichlorobenzene sublimate, meaning they go from a solid straight to a vapor. The vapor is toxic to the moths.

For either of these chemicals to be effective, they need to be placed with the clothing in a sealed container so the vapors can build up and kill the moths. In a sealed atmosphere like this, the vapors are not harmful to people because they are contained. The main threat would occur when opening the containers, or from wearing clothes immediately after opening (especially a problem for infants). A solution is to open the containers outside and let the clothes hang and air out for a day before wearing.
[edit] Uses and risks

In addition to repelling insects such as moths and silverfish, mothballs are used as a stovepipe cleaner, snake repellent, and to keep away mice or other pests. Mothballs have also been used by some campers to keep bears away from their food or even their entire campsite.[citation needed]

To clean the pipes of a wood burning stove, one or two mothballs thrown into the fire will help to loosen soot and creosote.[citation needed]

The main concern about the use of mothballs as a snake, mice, or animal repellent is their easy access to children, pets, and beneficial animals. Leaving them in a garden or in a living space unprotected makes it very easy for unintended victims such as children and pets to gain access to them. Mothballs are highly toxic when ingested, causing serious illness or death. In addition to this, using a very large quantity of mothballs in a basement or a living space may cause serious respiratory problems in people living in the space. [1]

It has also been suggested that the toxic chemical in mothballs will bond to garden soil, causing damage to it. Research has shown that a weak bond can occur, but naturally occurring soil microbes will break down the toxic component of mothballs over extended periods of time. In addition to this, the toxic effects of mothballs may also kill beneficial soil insects while it is present in soil. [2]

Mothballs have been used for solvent abuse by adolescents.[3][4] Mothballs have also been found to be a carcinogen[5].

In the Mythbusters episode "Scuba Diver, Car Capers" it was shown to be "plausible" that adding mothballs to a car's fuel tank would increase its horsepower.