dr. david ross was a top drug safety reviewer for the food and drug administration. he left the agency after ten years frustrated that it had approved drugs he says put patients at risk. ross says the fda's drug safety testing is not what you might think. >> i think the average person imagines the fda has a place where all these scientists are working, you know, sometimes around the clock testing drugs to make sure they're safe. is that the way it works? >> no. there are a large number of scientists that work around the clock, but they're not themselves testing the drugs. >> so who is responsible for getting the drugs tested for safety? it's actually the pharmaceutical companies themselves, and the fda often doesn't see the results of those tests until drug companies up want approval to sell their products. with thousands of drugs on the market, most of the time that system works. even so, ross says there are still serious flaws. >> it's not that every new drug is going to develop a problem, but we have no way of knowing when something is going to go bad. >> even whe