Why not just have the little chillren pee in a cup?
Much more effective sample, no?
No. Think of hair as a "permanent record." A lot of stuff flushes out of your body and becomes undetectable via urine in a couple of days.
Funny thing though pot takes 70 to 90 days to flush out and is actually more beneficial than harmful in many ways as the culture is slowing learning.
My question to you though:
I’d heard pot can only be detected with a urine sample, not blood nor hair follicles - both of which are slower and extremely expensive. Hair follicle tests approx $1000.00 iirc.