About five percent of specimens submitted did not originate in the body of the person being tested. Most were artificial urine.
Labs are continually having to change how they run tests. “Labs have moved on to test for other chemicals you’d expect to find in real human urine, as well as smelling specimens and shaking them to see if they foam naturally.”
I’m not sure I’d want to be person sniffing urine. Read more about how people fake tests - including using something called the Whizzinator - here .