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BALTIMORE — Washington, D.C., is launching a rat birth control program to lower the rodent population in the city.
The pilot program is set to begin this spring with the distribution of ContraPest, according to DC Health officials.
Baltimore used the rodent contraceptive during a similar program from April 2025 to October 2025. The program's success spurred a city-wide expansion on Feb. 24, according to Baltimore's Department of Public Works.
ContraPest uses the chemicals 4-Vinylcyclohexene Diepoxide and Triptolide to suppress fertility in female and male rats, officials said.
Addressing the rodent population
Like Baltimore, D.C. also faces ongoing issues with rodents.
In 2025, pest control company Orkin ranked D.C. as the sixth "rattiest" city, while Baltimore ranked at no. 12.
Aside from being a significant nuisance for neighbors and businesses, rats also impact public health in communities as they carry and transmit diseases and parasites.
A study released in February 2025 estimated that the "war on rats" costs about $500 million per year. Some areas, including D.C., have seen a spike in their rodent populations amid warming temperatures due to climate change, the study found.
Baltimore's rat birth control success
In April, officials with the Department of Public Works said Baltimore's pilot program showed a decline in rat activity in targeted areas. The program also resulted in a slight decrease in rat burrows in some areas.
As of April, the department said ContraPest bait stations have been deployed across all 14 Baltimore city council districts as part of the pest management strategy.
ContraPest is administered through tamper-resistant stations that are placed in areas that see high rat activity, according to the department. The stations are also placed in areas where frequent rat-related service calls are made.
