Senator Chuck Schumer (D-New York) issued a statement Sunday calling for federal protections to guard consumers from a "privacy nightmare" that could be created by Fitbit and other wearable fitness trackers.

Specifically, Schumer said he was worried companies behind Fitbit and similar products could sell data from these devices to third parties.

"Personal fitness bracelets and the data they collect on your health, sleep, and location, should be just that — personal. The fact that private health data — rich enough to identify the user’s gait — is being gathered by applications like Fitbit and can then be sold to third-parties without the user’s consent is a true privacy nightmare," Schumer said.

Schumer's press release announcing his concerns about FitBit declared, in all capital letters: "WITHOUT THEIR KNOWLEDGE, FITBIT BRACELETS & SMARTPHONE APPS ARE TRACKING USER’S MOVEMENTS AND HEALTH DATA THAT COULD BE SOLD TO THIRD PARTIES." In his statement, the senator called on the Federal Trade Commission to require companies to notify consumers if their fitness and location data could be sold to third parties — and to allow users to opt out of these deals.

"If companies of fitness devices have the ability to sell personal health data to insurers, employers and others, users should be alerted and given the opportunity to decline," Schumer said. "The FTC should require fitness devices and app companies to adopt new privacy measures that will help conceal the identity of individuals and develop policies to protect consumer information in the event of a security breach."

Schumer's press release noted the FTC "has openly voiced its concern about the selling of personal fitness data between companies, but has yet to take action to push application developers and other fitness monitoring companies to provide an opt-out opportunity." The press released also suggested that, without adequate protections, "users’ health information obtained via these trackers could be sold to insurers, mortgage lenders, or employers."

Update (8:31 p.m.): A Fitbit spokesperson said the company did not sell data to third parties and that it would like to "work with" Schumer.

"Fitbit does not sell user data. Our privacy policy prevents us from doing this. We are committed to our users' privacy and welcome the opportunity to work with Senator Schumer on this important issue," the spokesperson said.