How long do trace amounts of THC stay in your system?

Answer 1

The writer, who once ran a testing program, knows of one instance where it was detected in small quantities after 42 days. THC metabolites (which are what the test looks for) are stored in fat. The heavier you are and the more you have smoked, the longer it lasts. Even in a thin person it would be detectable for at least two weeks if you've smoked much.