I have a friend that has a son that is going in for a drug test by urine. He has been taking niacin and vit C pills and drinking green tea detox and about 2-3 gallons of water each day. He smoked a little a week ago and started taking these things 3 days ago. What are his chances for passing the urine drug test. They both are worried and have checked the internet for answers and can not find any certain answers