Four U.S. Senators sent a letter to the acting administrator of the Transportation Security Administration this week asking for an accounting of Hartsfield-Jackson International employee badges that are lost or stolen.

The letter comes after the Atlanta airport acknowledged that some 1,450 employee badges had gone missing over a period of about two years, out of a total of about 39,000 such employee badges in use at the airport. The airport said the badges are de-activated once reported lost or stolen, and each displays a photo of the employee. An employee with a valid SIDA or Secure Identification Display Area badge uses it along with a PIN number to access secure areas of the airport. Hartsfield-Jackson general manager Miguel Southwell said the number of total lost or stolen badges amounts to less than 2 percent of the total number of badges per year.

“We take the loss and theft of employee badges very seriously,” airport spokesman Reese McCranie said in a written statement. “At no time has anyone with a lost or stolen badge successfully gained access to the secured areas of the Airport.” Because of the safeguards in place, “we do not believe that this poses a security threat to the Airport,” he added.

The letter from Senate commerce committee chairman John Thune, ranking member Bill Nelson, aviation subcommittee chair Kelly Ayotte and ranking subcommittee member Maria Cantwell asked the TSA for “a full accounting of the number of SIDA badges lost, missing or otherwise unaccounted for” at Hartsfield-Jackson, as well as the percentage of SIDA badges unaccounted for at other airports.