United States Senators have joined together in a bipartisan effort, calling on rideshare companies Uber and Lyft to strengthen their protective policies against transporting human trafficking victims.

In two letters Monday, lawmakers urged Uber to reconsider a new service that would allow children ages 13-17 to request rides and travel alone. The company previously prohibited those under 18 from riding without an adult, though many teenagers still used the app.

The letters were sent to Uber CEO Dara Khosrowshahi and Lyft CEO David Risher, with Senators Richard Blumenthal (D-Conn.), Marsha Blackburn (R-Tenn.), and Jon Ossoff (D-Ga.) citing reports that document the prevalence of apps like theirs in sex trafficking cases.

While the Senators said they recognize that the new policy “has benefits, in that it provides parents and guardians with additional reliable transportation options for their children that they can monitor and track ... given the reported prevalence of ride-hailing apps in sex trafficking, however, we are extremely concerned about the impact this change could have on the trafficking of minors.”

While Uber and Lyft have each have programs to help drivers recognize signs of trafficking, the Senators noted more rigorous measures must be taken. They asked how the companies combat trafficking, what the reporting protocol for suspected cases entails, what records of incidents are kept, and what resources are available for riders. They requested a response by June 26.

“Tragically, ride-hailing apps like Uber have been used for sex trafficking. Reports from survivors indicate that ride-hailing apps are among the most used means of transportation in sex trafficking,” they wrote. “We are concerned that the measures taken to date are insufficient to address trafficking on the company’s ride-hailing service, especially given Uber’s recent announcement. The company can and must do more to shield everyone – both children and adults – from trafficking."

If you suspect human trafficking, call the National Human Trafficking Hotline toll-free at (888) 373-7888.