Amazon will have to answer questions from a bipartisan group of U.S. senators over its biometric data collection, including its palm print recognition system.

Amazon began using its biometric data collection via a program called Amazon One, which allows customers to make their payments through palm print scanning and eliminate the need for cash. Instead, the system would scan the customer’s palm for credit card information, according to The Hill.

In a letter assigned to Amazon’s CEO on Thursday, Aug. 12, the group of three lawmakers, including Sens. Amy Klobuchar (D-Minn.), Bill Cassidy (R-La.), and Jon Ossoff (D-Ga.), were especially unsettled by the company’s management of the data they can collect.

“Amazon’s expansion of biometric data collection through Amazon One raises serious questions about Amazon’s plans for this data and its respect for user privacy, including about how Amazon may use the data for advertising and tracking purposes,” they wrote.

Aside from concerns over Amazon’s handling of the data, which might violate biometric privacy laws, the senators were also worried that the system would be used for unfair competition.

“We are also concerned that Amazon may use data from Amazon One, including data from third-party customers that may purchase and use Amazon One devices, to further cement its competitive power and suppress competition across various markets,” they said, according to Reuters.

Giving a deadline until the end of August, the lawmakers wanted the e-commerce giant to detail its plan for developing Amazon One, as well as who they had sold or authorized the technology to, Reuters revealed.

They also inquired about the number of customers registered for the system, how the data is utilized, and whether it is ever combined with facial recognition technologies.

An Amazon spokesperson cited a FAQ about the palm sensors instead of giving comments. 

The FAQ ensured that the palm photos are highly encrypted and kept in a safe storage place, and clients who wish to leave the program can have their biometrics removed.

“We take data security very seriously and protect sensitive data, such as your palm signature and payment information, at rest and in-transit in accordance with Amazon’s high security standards,” the FAQ said. “Your palm data and payment information are not stored on the device and multiple layers of security controls protect your data at all times, including, but not limited to, encryption, data isolation, and dedicated secure zones with restricted access controls.”

Amazon’s history with handling their biometric data collection had raised concerns among privacy advocates, especially when it involved them sharing the information with law enforcement.

During the height of anti-police brutality protests last summer, the business halted the sale of facial recognition equipment to law enforcement, which was extended this year. According to research, technology is less accurate with individuals of color and women across the board. 

The Hill added that Amazon’s “smart” doorbell brand Ring had been criticized for giving law authorities more monitoring power.