Raccoons prefer life in quiet forested areas with plentiful water nearby, but sometimes their quest for food or a den site leads them too close for human comfort. Highly adaptable, raccoons adjust quickly to urban areas or anywhere with plentiful food and shelter. While many raccoon repellents are available, mothballs are not among them. This chemical pesticide, designed to deter and kill moths, is restricted from use against raccoons throughout the United States.
Mothballs contain pesticides, usually paradichlorobenzene or naphthalene, that slowly vaporize over time. The U.S. Environmental Protection Agency states that exposure to these chemicals can cause nasal cancer, and other studies link them to liver damage and other serious illnesses. If mothballs are left in an attic or crawlspace to repel raccoons or other creatures, these chemicals can seep into the rest of the house, exposing anyone living there. If left as a repellent outside, mothballs can be ingested by animals such as dogs or cats -- or even small children -- which could prove fatal.
The National Pesticide Information Center reports that mothballs are registered for pesticide use against moths only. They are intended for use in small, airtight enclosures such as trunks or other storage containers, not in open areas such as attics or basements where raccoons may find their way in to your home. They should never be used outdoors in open areas, even high out of other animals' reach. Any use other than the registered use is illegal. Not only is mothball use as a pesticide against raccoons prohibited by law, the effectiveness as a raccoon repellent is unproven.
According to the Environmental Protection Agency, natural plant oils like mustard oil have been proven to deter raccoons from rummaging through trash cans and gardens. Specialized live traps can also humanely remove raccoons from houses without injuring the animal or spreading dangerous pesticides such as mothballs around. The best prevention against unwanted raccoons is to remove the attractions that draw them in. Keep trash cleaned and confined where raccoons can't reach it, and cover chimney openings and similar entrances to prevent raccoons entering.