who okays drug testing? we want to ask how that s approved. where are some of those testing taking place. some people didn t like our questions. you may not like the answers. chris hansen with another hidden camera case from the hansen files. welcome to dateline, everyone. i m lester holt. from crooked lottery clerks on to criminal day care providers, over the years dateline s hidden cameras have exposed all sorts wrongdoing. now chris hansen is opening up the hansen files again with an investigation that could change the way you look at the drugs in your medicine cabinet. what have you uncovered? nearly half of all american report taking a prescription drug within the last month, so he we wondered how good is the system that makes sure those drugs are safe? as our hidden camera investigation found out, not good enough. americans fill a stunning 4 billion prescriptions a year, and each time we go to the pharmacy, we ve gron accustomed of seeing shelves lined with