If your son stops smoking, THC can stay in his urine for a while. For daily users, it might take up to 30-60 days to test negative, but this can vary based on metabolism and other factors.
Yes, even a very short drag of marijuana can show up on a urine test. The detection time can be anywhere from a few days to a week, depending on how much was consumed and individual metabolism.
Chronic marijuana use generally refers to regular, frequent use over a long period. Two to three months of daily use might be considered chronic by some standards, but it’s often seen as a moderate use pattern.