There are no toxic baits registered for controlling chipmunks. Baits that are used against rats and mice in and around homes will also kill chipmunks, although they are not labeled for such use and cannot be recommended. Moreover, chipmunks that die from consuming a toxic bait inside structures may create an odor problem for several days. Some states have Special Local Needs 24(c) registrations for chipmunk control for site-specific use.
Consult a professional wildlife control operator or Wildlife Services biologist if chipmunks are numerous or persistent.
Fumigants
Fumigants are generally ineffective because of the difficulty in locating the openings to chipmunk burrows and because of the complexity of burrows. Aluminum phosphide is a Restricted Use Pesticide that is registered in many states for the control of burrowing rodents, including chipmunks. It is available in a tablet that reacts with soil moisture when dropped into the burrow, generating phosphine, an extremely toxic and flammable gas. Aluminum phosphide, however, must not be used in, under, or even near occupied buildings because there is a danger of the fumigant seeping into buildings. If you are considering the use of aluminum phosphide, be sure to download and review the label (a small booklet) before purchasing any material. This will help you determine if aluminum phosphide is appropriate for your situation.
Gas cartridges are registered for the control of burrowing rodents and are available from garden supply centers, farm stores, hardware stores, seed catalogs, or the USDA Wildlife Services program. The openings of chipmunk burrows may have to be enlarged to accommodate the commercially or federally produced gas cartridges. Gas cartridges should not be used under or around buildings or near fire hazards since they burn with an open flame and produce a tremendous amount of heat. Carbon monoxide and carbon dioxide gases are produced while the cartridges burn; thus, the rodents die from asphyxiation.
Resources: (online)
Chipmunks
Tips on hiring professionals
Fumitoxin (a brand of aluminum phosphide) label booklet
