3-D imaging machines have begun to be removed from airport security checkpoints across the country, including Chicago’s O’Hare International Airport.

The machines also known as “backscatter” devices have drawn criticism from opponents who belive the machines are invasive and could pose a health risk.

Users who consent to the use of the X-Ray technology have a detailed image of themselves underneath their clothing pop up on a screen for TSA agents to look at. If a user does not consent to an X-ray they are subjected to a full body pat down.

The removal of X-ray machines at O’Hare started last month and is expected to be completed in January according to the Transportation Security Administration. The TSA also says the newer machines should help reduce wait times at security checkpoints.

“We support the TSA’s efforts to continue to create that security and a more efficient security checkpoint process at chicago’s airports,” said Chicago Department of Aviation spokesperson Karen Pride.

Pride said the airports are doing everything they can to accommodate the TSA.

Neither the TSA or the Chicago Department of Aviation would address a claim that “safer” machines are being brought in to replace the current ones.

According to an investigation by ProPublica, the new machines are allegedly safer and rather than displaying a person’s body, show a generic cartoon image instead.

A statement released by the TSA said, “In an effort to ensure the most efficient and effective use of security technology, TSA is strategically reallocating backscatter advance imaging technology units in order to allow for expanded use of advance imaging technology units at other airports.”

The one point that both agencies would confirm is that the X-ray machines are not being permanently removed.