The typical rat that New York City subway riders encounter on the tracks may have as many as 80 brothers and sisters running around with him. A new plan, hatched by the Metropolitan Transportation Authority, wants to bring the rat birth rate down to zero, by fighting the subway system’s thriving rat population with sterilization.
The New York Times reported on the agency’s new plan to host a multi-month field study, funded by the National Institute of Health, of ContraPest "a non-lethal, environmentally friendly rat fertility management bait."
According to the MTA’s fact sheet, "ContraPest accelerates the natural egg loss in female rats which eventually leads to permanent, irreversible sterility." Its manufacturer SenesTech has used the product to help reduce rat populations on farms throughout Asia. The release adds that ContraPest won’t affect the fertility of animals that might snack on the rats or the health of the environment or humans that come into contact with the product. Female rats would have to eat 8% to 10% of their body weight in ContraPest for about a week to see their litter sizes shrink within 4 weeks and eventually become sterile within 8 to 12 weeks.
According to the Times, one challenge of the new approach is "offering the rats a bait that they might prefer to the subway system’s daily treasures—half-eaten gyros and chicken fried rice, stale pizza and discarded churros." But the bait seems to have taken a page from food scientists to hook the rats on ContraPest: it’s packed full of the holy trinity of sugar, salt, and fats.