Not the toilet! The dirtiest place on the plane is ...

Excerpt from the 2017-07-08 United Daily News

US travel math, sending microbiologists to the United States five airports and take four flights to collect samples and found the plane has six dirtiest places, of which the front of the tray the most dirty (2,155 bacterial units), or even 8 times more than the toilet flush toilet.
The 6 dirtiest places at the aiport and on the plane.
Seat tray on the plane: 2,155 bacterial units.
Water fountain button: 1240 bacterial units.
Air conditioning air vent: 285 bacterial units.
Toilet flush button: 265 bacterial units.
Seat belt buckle: 230 Bacterial units.
Toilet door lock: 70 bacterial units.