Mothballs are made of naphthalene or para-dichlorobenzene, two pesticides that transform straight from a solid to a gas. Because of its flammable nature, naphthalene is a less common component of modern mothball production. The chemicals in mothballs repel insects and are often used in areas where clothing is stored.
Fumes from mothballs can be harmful to humans. Clothing that has been sealed in a bag with mothballs should be aired out before wearing. Contact with the eyes or the skin can cause irritation and burning. Long-term exposure to mothball fumes can cause damage to the eyes, breathing difficulty, weakness and fatigue.