Using a specific light wavelength, the scanners cause a fluorescence in even minuscule amounts of fecal contamination; it shows up on a built-in display as a bright red spot on a person's dirty hand.
"Nobody wants to have doo-doo on their burger," said Jacob Petrich, a biophysical chemist at Iowa State University.
"If you only eat beer and cheese pizza, what kind of signatures are you going to get," asked Petrich. "it's just a question of technology, of how you look at the spectral signatures of diets."
New Technology Could Detect Dirty Hands:
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