Mothballs are used to prevent insects from damaging stored clothing. Chemical mothballs are made from either naphthalene or paradichlorobenzene. Both are toxic, and are suspected of causing cancer. Cedar balls are marketed as a more natural moth repellent, but even cedar oil carries risks to animals. The best way to prevent moths from damaging clothes is to seal clothing in a container they can't get into.
Naphthalene is a pesticide that changes from a solid to a gas. It is manufactured from coal tar or oil. Exposure to the fumes can cause headaches, nausea, dizziness and vomiting. It can cause anemia if a person or animal eats a mothball, or breathes enough of the vapors. Children who have consumed naphthalene mothballs can have fever, diarrhea, abdominal pain and pain while urinating. Infants exposed to blankets and clothing that have been treated with mothballs without being washed have developed anemia. Naphthalene breaks down into alpha-naphthol in the body, which can cause liver and kidney damage.
Paradichlorobenzene is also a solid that changes to a gas. It causes eye, nasal and skin irritation, and inhaling the vapors can cause nausea, dizziness, vomiting, fatigue and headaches. It can cause tremors, vomiting and abdominal pain in pets, and is suspected of causing liver and kidney damage. Paradichlorobenzene has been linked to cancer in mice, though it is not certain if it causes cancer in humans. Paradichlorobenzene travels through the blood and fatty tissue, and is excreted in milk and urine.
Cedar balls and oil are marketed as an alternative for moth control. Cedar can be toxic to pets that eat the balls or breathe the fumes. Cedar is known to cause liver damage in small animals kept on cedar wood shavings. Cedar fumes can also cause allergic reactions in humans.
There have been cases of people deliberately inhaling or ingesting naphthalene and paradichlorobenzene. Teenagers are known to suck on mothballs, and to place the balls in plastic bags to concentrate the fumes, then breathe from the bag. In 2006, two teenagers were hospitalized for scaly skin, unsteady gait and slow mental reaction times.