The legal limit for such substance is 2.0 ng/ml and a normal person usually has between 0.1 and 0.2 with a maximum of 0.6 ng/ml.
According to the legal standard, the concentration should not exceed 2.0 ng/ml; however, a healthy individual generally maintains levels between 0.1 and 0.2 ng/ml, with a maximum of 0.6 ng/ml.