Expressing concern about the tracking of retail shoppers at physical locations, Sen. Charles Schumer (D-N.Y.) requested that the Federal Trade Commission take action.

Writing to FTC Chairwoman Edith Ramirez, Sen. Schumer said that major national retailers – such as American Apparel, Benetton, and Family Dollar – rely upon technology to track consumers’ movements through their stores using the Wi-Fi on cell phones. Stores collect data about how a shopper navigates through the aisles and how much time is spent looking at specific merchandise.

“Geophysical location data about a person is obviously highly sensitive; however, retailers are collecting this information anonymously without consent,” Sen. Schumer wrote. “As these technologies become more widespread, it is imperative that we protect our consumers from unknowingly giving out information they do not desire to.”

Some retailers save the data “in perpetuity,” Sen. Schumer said in a statement, adding that even children can be tracked. Consumers can halt the tracking only by turning off the Wi-Fi on a smartphone or leaving a phone outside the store. But many consumers are unaware they even need to make such a choice, he said. Stores are “treating the consumers as the products” and are able to combine the in-store data with other information found online to create “an incredibly detailed profile of each shopper.”

“I would ask that the Federal Trade Commission investigate this practice, and clarify that it is an unfair or deceptive trade practice to fail to notify shoppers that their movements are being tracked in a store or to give them an opportunity to opt out of this type of tracking before it begins,” he wrote.

To give consumers the opportunity to opt out of being tracked, Sen. Schumer suggested that retailers send electronic notices to a consumer’s phone before the software begins to work.

To read Sen. Schumer’s letter to the FTC, click here.

Why it matters: The use of the tracking technology has been on Sen. Schumer’s radar for years. In 2011, he objected when he learned that tests of the software were being conducted in U.S. malls. The malls stopped their use of the software after Sen. Schumer spoke out. And earlier this year, Sen. Al Franken (D-Minn.) responded to news reports about shopper tracking by sending a letter to the CEO of Euclid Analytics, a developer of tracking software. Responding to Sen. Franken’s questions about the “troubling” technology, Euclid said sensors scramble the device information for consumers so that the company cannot collect such information as names, addresses, and phone numbers from shoppers. Despite the assurances, lawmakers continue to push for oversight.