FLAGSTAFF -- During a tour of trash rooms in New York City's subway system this spring, a worker swung his steel-toed boot repeatedly toward a door that wouldn't open.
He was trying to part a sea of rats, he told a visiting Flagstaff delegation.
"The floor was moving," with rats, researcher Cheryl Dyer remembered.
The rats feast on pizza and other leftovers, and they multiply in garbage-storage rooms underground, startling the city workers who remove the trash or repair subway tracks.
They crawl up the legs of track workers' pants and rode a tide up into New Yorkers' apartments during Superstorm Sandy.
So New York City called on a Flagstaff company to put the rats on birth control, of sorts, in a first-of-its-kind $1.1 million experiment funded by the National Institutes of Health. The project will start this summer.
"They wanted an alternative to poison, which doesn't work," said Dyer, co-founder of SenesTech Inc.
It's a Flagstaff company that has created infertility drugs for mice and rats.
SenesTech's plan is to shrink the whole population at a few New York subway stops.
One female rat can normally have a dozen pups every three weeks.
Dyer and SenesTech Inc. co-founder Loretta Mayer have spent about a decade refining a non-toxic compound that rats can eat to speed along menopause and cut the size of litters in half or by one-quarter -- and sometimes to none.
The ingredients include the compounds that make plastic pliable and some Chinese herbs, all put into the form of an edible syrup.
Flagstaff SenesTech workers wearing hazardous materials suits (to protect from the dozens of diseases rats carry) will attempt to estimate population sizes, then place bait.
The company employs a dozen, and all but one are Northern Arizona University graduates or students.
The syrup will be locked in boxes accessible to rats in Grand Central Station and three other subway stations in New York City.
Right now, the trick is trying to create a bait that matches the flavors in the trash in those subway stations.
SenesTech employees will be able to measure how readily the bait is consumed via an ultraviolet dye that will appear in rat droppings and show up as pink in their whiskers.
"Our bait is cleared within minutes in the liver," said Mayer, who formerly taught biology at NAU.
Researchers will ultimately trap and kill some rats to examine whether the compound aged ovaries as expected.
Rodent control is about a $1.5 billion business in the United States.
This company's proposal is different in that it isn't extermination.
"Instead of thinking you can get rid of every rat that lives, accept that they're going to live in the trash or on your farm," and plan for some losses, Dyer said.
SenesTech has had experiments to control rat or mice populations in Laos, Indonesia, the Philippines, Australia, New Zealand and Britain.
"I cannot tell you the number of countries that have contacted us," Mayer said.
SenesTech was founded in 2004. Mayer and Dyer are taking the steps needed to register their compound with the U.S. Environmental Protection Agency and hope to have the product on the market in the fall of 2014.