Wait what kind of DT are you talking about? A lot of the employers around where i live will make you take a hair folocule test which are considerablly harder to pass then piss test and they can test for like 3 to 6 months of use.
One time I thought i was slick and cut all my hair off (ALL OF IT, I really wanted that job
) and they used the scrapings off of my finger nail!! And I was f*cked that way...and hairless for a few days.
Ah well, that's why i stick to in frequent cocaine use, as it's in and out of your system in 24 hours.